Abstract

Candidemia and other forms of candidiasis are associated with considerable excess mortality and costs. Despite the addition of several new antifungal agents with improved spectrum and potency, the frequency of Candida infection and associated mortality have not decreased in the past two decades. The lack of rapid and sensitive diagnostic tests has led to considerable overuse of antifungal agents resulting in increased costs, selection pressure for resistance, unnecessary drug toxicity, and adverse drug interactions. Both the lack of timely diagnostic tests and emergence of antifungal resistance pose considerable problems for antifungal stewardship. Whereas antifungal stewardship with a focus on nosocomial candidiasis should be able to improve the administration of antifungal therapy in terms of drug selection, proper dose and duration, source control and de-escalation therapy, an important parameter, timeliness of antifungal therapy, remains a victim of slow and insensitive diagnostic tests. Fortunately, new proteomic and molecular diagnostic tools are improving the time to species identification and detection. In this review we will describe the potential impact that rapid diagnostic testing and antifungal stewardship can have on the management of nosocomial candidiasis.

Introduction

Nosocomial candidiasis (candidemia and other forms of invasive candidiasis [IC; infection involving other normally sterile body fluids and tissues]) constitutes a life-threatening condition in immunocompromised and critically ill patients [ 1 , 2 ]. Although this is widely acknowledged, it is also clear that the frequency of infection and the associated mortality has not decreased over the past two decades despite the introduction of several extended-spectrum triazole and echinocandin antifungal agents for use in prophylaxis, empiric and targeted therapy [ 1 , 3–8 ]. Whereas the high mortality rate is in part related to the critically ill patient population at risk for IC who are subjected to both invasive and immunosuppressive modalities, it may also be attributed to the difficulty in diagnosing Candida infection coupled with challenges in administering adequate antifungal therapy (timely administration, right drug, right dose, sufficient duration) to those patients who need it [ 9–17 ]. Although this may suggest a role for empiric or presumptive therapy in the management of candidiasis [ 10 , 18 , 19 ], criteria for initiating such therapy remain poorly defined and frequently lead to widespread administration of antifungal therapy with the attendant risks of toxicity, resistance selection and unnecessarily high costs of antifungal treatment regimens [ 10 , 18 , 20–22 ]. These issues are compounded by the lack of rapid, sensitive and specific diagnostic tests [ 9 , 23 ]. Clearly, antifungal stewardship should be able to make considerable improvements in the process of diagnosing and treating IC [ 24 ]. In this review we will discuss the potential role of antifungal stewardship and how rapid diagnostic methods can impact stewardship efforts in the management of candidiasis.

Burden of disease

Candidiasis is the most important fungal infection in hospitalized individuals worldwide [ 1 , 2 , 8 , 18 , 25 ]. A US population-based survey conducted by the Centers for Disease Control and Prevention (CDC) during 2008–2011 found a mean annual incidence of candidemia per 100,000 population of 13.3 in Atlanta and 26.2 in Baltimore [ 5 ]. Rates were highest among adults aged ≥65 years (Atlanta, 59.1; Baltimore, 72.4).Similar findings were noted in Denmark [ 3 ] where the annual incidence was 8.6/100,000 population with the highest rates seen at the extremes of age (<1 yr [11.3/100,000] and >70 yrs [37.1/100,000]). These elevated candidemia rates are in contrast with those of other Nordic countries (range 1-4/100,000) 3 . Likewise, high incidence rates (6.5/1,000 intensive care unit [ICU] admissions) were recently reported from a multicenter study conducted in India [ 26 ]. Notably, the emergence of multi-drug-resistant (MDR; resistant to two or more antifungal classes) strains of C. glabrata in the United States, Latin America, Italy, France, and Denmark [ 27–35 ] and C. tropicalis, C. auris , and C. krusei in India [ 26 ] serve to emphasize the importance of regional and local surveillance efforts.

Infection with Candida was found to be second in rank-order (after Staphylococcus aureus ) in European and North American ICUs and Candida is presently the third leading cause of catheter-associated bloodstream infection (BSI) in the United States [ 25 , 36 ]. Whereas Candida infection generally occurs in patients with a large number of comorbidities [ 2 , 4 , 13 , 37–40 ], the excess mortality (49%) and length of stay (LOS; 30 days) in hospital exceed that of most other healthcare-associated infections (HAI) [ 7 , 20 , 24 , 41–53 ]. Likewise, the costs associated with Candida infection (range $6,214 to $142,394 [US $] per patient) are among the highest of any HAI [ 20 , 41 , 45 , 48 , 49 , 52–54 ]. Improvements in the diagnosis and management of candidal infections will require a much more rapid, sensitive, and specific approach to diagnosis as well as increased attention to the time-sensitive aspects of administration of antifungal therapy [ 24 , 55–62 ].

Principles of antifungal stewardship

The basic principles of antifungal stewardship with a focus on IC are shared with the already established antibacterial stewardship programs [ 52 , 63 ]. The major purpose of all stewardship efforts is to optimize the use of antimicrobial agents to achieve the best outcomes while minimizing adverse events and limiting the selection pressures that drive the emergence of resistance [ 52 , 60 , 63–65 ]. Guidelines for the development of an effective antimicrobial stewardship program have been published by the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA) [ 63 ] and adapted to the needs of antifungal stewardship by Ananda-Rajah et al. [ 24 ]. Key recommendations from these Guidelines include, but are not limited to, the following: (i) The composition of the stewardship team must be multidisciplinary and optimally should include an infectious diseases (ID) physician, a clinical pharmacist with ID training, a clinical microbiologist, an information system specialist, an infection control professional and a hospital epidemiologist. Collaboration between these individuals and with the Infection Control and Pharmacy and Therapeutics committees is essential and must be supported by hospital administration and medical staff leadership. (ii) The foundation for the stewardship program rests on two core strategies that are complementary and include prospective audit with intervention and feedback and formulary restriction and preauthorization. These strategies coupled with a strong educational effort by clinical specialists have been shown to reduce unnecessary antimicrobial use and result in substantial antimicrobial cost savings. The effect of such efforts on antimicrobial resistance is less clear. (iii) Multidisciplinary development of evidence-based practice guidelines incorporating local microbiology and resistance patterns should be widely available throughout the institution. Implementation of these guidelines may be facilitated by provider education and feedback on antimicrobial use and patient outcomes. (iv) Antimicrobial order forms have proven to be an effective component of antimicrobial stewardship and can facilitate the implementation of practice guidelines. Order forms that require clinical indication as well as a defined duration of therapy may decrease antibacterial/antifungal courses and associated expenditures. Such order forms should not replace clinical judgement and requirements for renewal or extension of the course of treatment must be clearly communicated in order to avoid inappropriate treatment interruption. (v) Streamlining or de-escalation of empirical therapy based on specific microbiological data (rapid species-level diagnosis, culture results and antimicrobial resistance profile) and elimination of redundant or unnecessary therapy can target the causative pathogen, resulting in decreased antimicrobial exposure and cost savings. While important, such efforts to control antifungal usage have been hampered by the suboptimal diagnosis of IC using current tests. (vi) An important aspect to consider in streamlining antimicrobial therapy is the conversion from parenteral to oral therapy (e.g., echinocandin to fluconazole) in patients where this is appropriate. A systematic plan for such conversion can decrease hospital stay and healthcare costs. Implementation at the institutional level may be facilitated by development of clinical criteria and guidelines allowing conversion to the use of oral agents. (vii) Healthcare information technology and computer-based surveillance can improve antimicrobial decision making by providing patient-specific microbiology results and susceptibility, target interventions, and track resistance patterns. (viii) Microbiological support is essential to direct patient-specific therapeutic interventions as well as assisting in infection control efforts. Implementation of newer immunological, molecular and proteomic test methods promise to enhance such efforts. It is the role of the clinical microbiologist to ensure that the correct testing methods are used and results reported and interpreted in a timely fashion in order to maximize their clinical impact. (ix) Monitoring of both process and outcome measures are important in assessing the impact of stewardship efforts on patient care, antimicrobial use and resistance patterns. This is important in order to evaluate the impact of antimicrobial stewardship as a measure of quality improvement and also as a means of providing feedback on the effectiveness of stewardship efforts to patient-care providers.

It is widely recognized that both the timing and selection of antimicrobial therapy (right drug, right dose, right patient) are directly related to the mortality and costs of treating HAIs. By ensuring that both timely and appropriate antimicrobial therapy is administered to the right patient, antimicrobial stewardship should both improve patient outcome (mortality and length of stay [LOS]) and also reduce the excess costs attributable to suboptimal antimicrobial use [ 55 , 61 , 66–70 ]. Notably, one of the major drivers for antifungal stewardship is the relatively high costs and toxicity of antifungal agents which is often greater than that of antibacterial agents [ 10 , 17–20 , 24 , 49 , 51 , 65–67 ]. It should be recognized that a strong focus on limiting unnecessary antibacterial treatment reduces the pressure for fungal overgrowth and thus the risk for IC [ 40 , 50 , 63 ].

Regarding the establishment of an antifungal stewardship program, one issue of concern is the difficulty in identifying those hospitalized individuals who are truly at the highest risk for Candida infection and for whom early treatment with systemically active antifungal therapy will be of benefit [ 68 ]. This is an especially daunting task when the current diagnostic tests (blood culture [BC], polymerase chain reaction [PCR], β-D- glucan [BDG]) are quite variable in terms of timeliness, sensitivity and specificity [ 9 ]. BCs require 2–3 days of incubation until turning positive and both BDG- and PCR-based methods are most often performed in reference laboratories with results available in days rather than hours [ 9 , 19 , 41 , 56 , 58 ]. The lack of adequate diagnostic testing methods has resulted in overutilization of antifungal agents in many instances [ 10 , 61 , 65 , 67 , 69 ]. Whereas the use of so-called Candida scores may reduce the overall population of patients exposed to empiric antifungal agents [ 68 , 70–73 ], such efforts are imperfect with sensitivities and specificities ranging from 27% to 90% and 37% to 93%, respectively [ 71 , 73 ]. There is a great need for more rapid, sensitive and specific diagnostic tests for the diagnosis of IC and as an aid in antifungal stewardship [ 65 , 68 ].

Whereas timely administration of antifungal therapy is an important goal of antifungal stewardship [ 24 , 65 ], overutilization of antifungal agents is often a much larger issue with implications for antifungal resistance, excess costs, toxicity and adverse drug interactions [ 10 , 55 , 60 , 66 , 67 , 74–77 ]. The administration of antifungal prophylaxis in patient populations where it has not been shown to be of value (e.g., echinocandin prophylaxis in the ICU setting) as well as misguided attempts to treat Candida colonization of urinary and/or upper respiratory tracts leads to overuse of antifungal agents and possible resistance selection [ 10 , 60 , 66 , 67 , 77 , 78 ]. The recognition of inappropriate use of antifungal agents and early discontinuation or de-escalation of drugs that are not required is an important role of antifungal stewardship [ 10 , 24 , 41 , 43 , 51–53 , 55 , 57 , 61 , 63 , 65–67 , 69 , 74 , 79 ]. These efforts may be enhanced by rapid and sensitive diagnostic tests for which the negative predictive value (NPV) is >99% [ 57–59 , 61 , 80 , 81 ].

In addition to problems identifying those patients that require antifungal therapy, there are several problems in administering antifungal therapy that impact the effectiveness and therapeutic outcome as well as the selection pressures for resistance [ 12 , 24 , 27 , 28 , 55 , 60 , 74 , 75 , 82 ]. Delays in initiation of therapy, selection of the most appropriate antifungal agent to cover the indicated species, ensuring that the appropriate dose is administered and that therapy is administered for the appropriate duration, including early discontinuation of therapy that is not indicated, all have a profound impact on the outcome of therapy in candidiasis [ 13 , 16 , 20 , 24 , 65 ]. In each instance correction of suboptimal clinical practices fall under the umbrella of maintaining the best standard of care for the patient while at the same time managing the excess costs that may be incurred [ 24 , 65 ]. The stewardship team should adapt the guidelines of expert panels such as the Infectious Diseases Society of America (IDSA) and the European Society for Clinical Microbiology and Infectious Diseases (ESCMID) guidelines for the management of candidiasis [ 22 , 83 , 84 ] to the local patient population and practice patterns [ 24 ]. Efforts to not only minimize the inappropriate administration of antifungal agents to uninfected (colonized) individuals but also to ensure that the selected agent is likely to be active against the target species (local epidemiology) are the heart of stewardship activities [ 75–77 , 85 ]. The fact that fluconazole is often administered at the wrong dose (too low; e.g., <12 mg/kg/day for C. glabrata and <6 mg/kg/day for other species) and for insufficient duration should be correctable through the guidance of the stewardship program [ 12 , 76 , 85 ].

The educational and monitoring role of the antifungal stewardship program is most effective when employing a multidisciplinary approach that includes input from infectious diseases, hospital epidemiology and infection control, critical care, pharmacy, microbiology, hospital administration and selected other healthcare providers (e.g., nursing, oncology, transplant, and hospitalists) [ 24 , 65 , 74 , 86 , 87 ]. Such diverse representation sends the message that stewardship is considered an important effort to improve the care of patients. Whereas the process of formulary management is familiar to most physicians and pharmacists, this is only part of the mission of antifungal/ antimicrobial stewardship programs [ 24 , 88 , 89 ]. Certainly both pre-prescription approval or post-prescription review and feedback are common practices but these approaches must be handled with care not only to identify deficiencies in prescribing practices but also to educate prescribers on the importance of candidiasis and the appropriate use of antifungal agents [ 24 , 74 , 78 , 89 ]. Ideally these efforts will build trust and an open dialog between the stewardship team and physician prescribers [ 89 ].

The stewardship team must identify the patient population at risk, taking into account both risk factors and prior antifungal exposure as well as associated cost considerations [ 39–41 , 43 , 51–53 , 57 , 80 , 90–92 ]. Whereas several studies have shown an economic advantage when effective antibacterial stewardship programs are in place [ 61 , 63 , 64 , 69 , 79 , 81 , 87–89 , 93 ], most antifungal stewardship efforts have shown improvement in the process of managing fungal infections but not necessarily an economic benefit [ 10 , 18 , 24 , 41 , 43 , 52 , 53 , 55 , 65 , 67 , 74–76 , 82 , 85–87 , 90 , 94 ]. Notably, a single center study by Standiford et al. [ 66 ] documented a $2,251,976 (US $) reduction in antifungal costs over a 3-year period with the institution of an antimicrobial stewardship program and the development of treatment guidelines for fungal infection in the institution. Similarly Guarascio et al. [ 77 ] have shown that an active antifungal stewardship effort resulted in two fewer days of echinocandin therapy with a savings of $1,013 (US $) per patient.

Risk factors

The lack of specific clinical findings and slow, insensitive diagnostic testing complicate the early recognition and treatment of candidiasis [ 65 , 68 ]. Most experts recommend the use of clinical risk factors to identify patients who may benefit from prophylactic or early empirical therapy in the proper clinical setting [ 40 , 68 , 95 ] (Table 1 ). Unfortunately, the predominant risk factors for candidiasis are common iatrogenic and/or nosocomial conditions [ 8 , 57 , 68 ]. The various Candida scores have been shown to provide some enrichment of candidiasis incidence for populations at risk; however, they are only 50% sensitive, which is why they are limited in use to clinical trial recruitment rather than routine patient care settings [ 68 , 70–72 ]. Additional meaningful stratification by independent risk factors will be required to identify those high-risk patients who would derive maximal benefit from early therapeutic interventions [ 40 , 57 , 96 ].

Table 1.

Candidemia risk factors for hospitalized patients. a

Risk Factor Possible role in infection 
Antimicrobial agents Provide vascular access 
(number and duration) b and promote fungal colonization 
Glucocorticoids Immunosuppression 
Age (<1 year, >70 years) Immunosuppression 
Chemotherapy b Immunosuppression 
 Mucosal disruption 
Malignancy Immunosuppression 
Colonization b Translocation across mucosa 
Gastric acid suppression Colonization and translocation 
Indwelling catheter b Direct vascular access 
 Central venous catheter Contaminated product (device or infusate) 
 Pressure transducer  
 Port  
Total parenteral nutrition Direct vascular access 
 Hyperglycemia 
 Contaminated infusate 
Neutropenia (<500/mm 3 ) b Immunosuppression 
Surgery (abdominal) Route of infection 
 Mucosal disruption 
 Direct vascular access 
Mechanical ventilation Route of infection 
Renal failure/hemodialysis b Route of infection 
 Immunosuppression 
Solid organ transplant Route of infection 
 Mucosal disruption 
 Direct vascular access 
 Immunosuppression 
Hospital or ICU stay Exposure to pathogens 
 Exposure to additional risk factors 
Severity of underlying illness Invasive procedure 
Risk Factor Possible role in infection 
Antimicrobial agents Provide vascular access 
(number and duration) b and promote fungal colonization 
Glucocorticoids Immunosuppression 
Age (<1 year, >70 years) Immunosuppression 
Chemotherapy b Immunosuppression 
 Mucosal disruption 
Malignancy Immunosuppression 
Colonization b Translocation across mucosa 
Gastric acid suppression Colonization and translocation 
Indwelling catheter b Direct vascular access 
 Central venous catheter Contaminated product (device or infusate) 
 Pressure transducer  
 Port  
Total parenteral nutrition Direct vascular access 
 Hyperglycemia 
 Contaminated infusate 
Neutropenia (<500/mm 3 ) b Immunosuppression 
Surgery (abdominal) Route of infection 
 Mucosal disruption 
 Direct vascular access 
Mechanical ventilation Route of infection 
Renal failure/hemodialysis b Route of infection 
 Immunosuppression 
Solid organ transplant Route of infection 
 Mucosal disruption 
 Direct vascular access 
 Immunosuppression 
Hospital or ICU stay Exposure to pathogens 
 Exposure to additional risk factors 
Severity of underlying illness Invasive procedure 

a Compiled from refs 2 and 8.

b Independent risk factor.

It is important to understand that the risk for candidiasis in the hospital is a continuum [ 8 , 40 , 44 ] (Table 2 ). Certain individuals are clearly at increased risk for acquiring candidemia (or any other nosocomial infection) during hospitalization as a result of their underlying medical conditions: patients with hematological malignancies and/or neutropenia, those undergoing gastrointestinal surgery, solid organ transplant recipients, premature infants and adults older than 70 years of age (Table 2 ). Among patients with candidiasis the mean time to onset of infection is 22 days of hospitalization [ 8 ]. Thus, candidiasis typically affects individuals with considerable comorbidities who have prolonged hospitalization.

Table 2.

Risk for candidemia is a continuum. a

• General risk factors upon admission to hospital  
 - Hematologic malignancy  
 - Neutropenia  
 - Abdominal surgery  
 - Solid organ transplant 
 - Premature infant  
 - Older adult (>70 years of age)  
• Specific exposures that further increase risk (OR odds ratio)  
 - Intensive Care Unit stay >7 days (OR, 9.73)  
 - Central venous catheter (OR, 7.23)  
 - Dialysis (OR, 18.13)  
 - Antibiotics (OR, 1.73 per antibiotic class)  
 - Total parenteral nutrition (OR, 8.87)  
 - Colonization (OR, 10.37)  
• General risk factors upon admission to hospital  
 - Hematologic malignancy  
 - Neutropenia  
 - Abdominal surgery  
 - Solid organ transplant 
 - Premature infant  
 - Older adult (>70 years of age)  
• Specific exposures that further increase risk (OR odds ratio)  
 - Intensive Care Unit stay >7 days (OR, 9.73)  
 - Central venous catheter (OR, 7.23)  
 - Dialysis (OR, 18.13)  
 - Antibiotics (OR, 1.73 per antibiotic class)  
 - Total parenteral nutrition (OR, 8.87)  
 - Colonization (OR, 10.37)  

a Compiled from refs 44 and 96.

Within the high risk groups of patients, specific additional exposures have been recognized as independent risk factors by multivariate analysis of data from matched cohort studies [ 8 , 40 , 96 ] (Table 2 ). These include the presence of vascular catheters, exposure to broad-spectrum antibacterial agents, renal failure, mucosal colonization with Candida spp., prolonged (≥7 days) ICU stay, and receipt of total parenteral nutrition (TPN). Compared with control patients without the specific risk factors or exposures, the likelihood of these already high-risk patients contracting candidiasis in hospital is approximately 2 times greater for each class of antimicrobial agents they receive, 7 times greater if they have a central venous catheter (CVC), 10 times greater if Candida has been found to be colonizing other anatomical sites, and 18 times greater if the patient has undergone hemodialysis [ 40 , 44 , 96 ]. Hospitalization in the ICU provides the opportunity for transmission of Candida among patients and has been shown to be an additional independent risk factor (10-fold increase in risk) [ 96 ]. When two or more of these risk factors are present, the probability of infection increases even further. Thus, Wenzel and Gennings [ 40 ] have demonstrated that if a patient in the ICU had exposure to four different antibiotics, his or her risk of candidemia would be approximately 35% given a baseline frequency of infection in the ICU of 5% (Table 3 ). However, after adding just one additional risk factor (e.g., colonization of another site such as urine or wound) the risk jumps to approximately 80% (Table 3 ). Thus, analysis of risk factors may help guide the application of antifungal therapy to those patients who are most likely to benefit from it [ 40 , 68 ]. Having said this it is important to recognize that despite the proven efficacy of the echinocandins in the treatment of IC, the available evidence does not support their use as prophylaxis in the ICU setting [ 72 ]. Risk stratification is also important for selecting patients to test for Candida biomarkers as a means of initiating early preemptive therapy even in the absence of clinical signs and symptoms [ 59 ]. Patients identified by these risk stratification tools should have improved outcomes; however, the severity of the underlying disease and other co-morbidities complicate this process and influence mortality independent of antifungal therapy. Unfortunately at the present time there are still a number of infected individuals who are not treated, and a larger group of uninfected individuals receiving costly and unnecessary antifungal therapy [ 68 , 70–72 ].

Table 3.

Risk for candidemia in intensive care unit (ICU) patients.

 Calculated risk of infection based upon 
  baseline risks of 1%, 2.5%, and 5% in ICU 
Exposure  patients with specific exposures 
Baseline 1% 2.5% 5% 
4 antibiotics 7% 17% 35% 
4 antibiotics plus colonization 40% 65% 80% 
6 antibiotics plus colonization plus hemodialysis 100% 100% 100% 
 Calculated risk of infection based upon 
  baseline risks of 1%, 2.5%, and 5% in ICU 
Exposure  patients with specific exposures 
Baseline 1% 2.5% 5% 
4 antibiotics 7% 17% 35% 
4 antibiotics plus colonization 40% 65% 80% 
6 antibiotics plus colonization plus hemodialysis 100% 100% 100% 

Adapted from ref 40.

Local epidemiology: Species identification, and antifungal resistance

In order to conduct antifungal stewardship effectively, providing guidance and information to clinicians faced with diagnosing and treating nosocomial candidiasis, the members of the antifungal stewardship team must have a firm understanding of the local epidemiology (e.g., the frequency of occurrence as well as the antifungal susceptibility profile of each species encountered in the hospital) [ 24 , 65 ]. In many institutions this information is readily available from the microbiology laboratory and should be summarized and distributed to the antifungal stewardship team as well as to clinicians that care for high risk patients [ 74 , 87 , 89 ]. In situations where such data are not available, efforts should be made to collect local information and in the interim data from national and regional surveys may be useful [ 5 , 94 , 97 , 98 ]. In the United States, Europe, and Asia, both sentinel and population-based surveys have been conducted over several years duration and may serve as a baseline for comparison with local epidemiologic data [ 3 , 6 , 7 , 23 , 26 , 34 , 38 , 97 , 99 ] (Tables 4 and 5 ).

Table 4.

Species distribution of Candida isolates from patients with candidemia: results from sentinel and population-based surveillance.

 % of total by surveillance program (No. of isolates) 
  SENTRY a  PATH b  CDC c 
Species (860) (3,648) (2,209) 
C. albicans 47 42 41 
C. glabrata 18 27 27 
C. parapsilosis 18 16 18 
C. tropicalis 11 
C. krusei 
Other 
 % of total by surveillance program (No. of isolates) 
  SENTRY a  PATH b  CDC c 
Species (860) (3,648) (2,209) 
C. albicans 47 42 41 
C. glabrata 18 27 27 
C. parapsilosis 18 16 18 
C. tropicalis 11 
C. krusei 
Other 

a Pfaller et al. [ 97 ].

b Pfaller et al. [ 98 ].

c Cleveland et al. [ 5 ].

Table 5.

Candida species antifungal susceptibility profile. a

  Susceptibility category as determined by CLSI Interpretive Criteria b 
Species AMB FLC ITR VOR Echinocandins 
C. albicans 
C. tropicalis 
C. parapsilosis  S/? c 
C. glabrata S/NS SDD/R SDD/R S/NS S/R 
C. krusei S/NS SDD/R 
  Susceptibility category as determined by CLSI Interpretive Criteria b 
Species AMB FLC ITR VOR Echinocandins 
C. albicans 
C. tropicalis 
C. parapsilosis  S/? c 
C. glabrata S/NS SDD/R SDD/R S/NS S/R 
C. krusei S/NS SDD/R 

a Abbreviations: CLSI, Clinical and Laboratory Standards Institute; AMB, amphotericin B; FLC, fluconazole; ITR, itraconazole; VOR, voriconazole; S, susceptible; NS, non-susceptible; SDD, susceptible dose dependent; R, resistant.

b Pfaller and Diekema, (100)

c MICs for echinocandins and C. parapsilosis are elevated compared to other species. Fluconazole is the preferred agents for this species.

Data compiled from Pappas et al. [ 22 ] and Pfaller and Diekema [ 8 ].

Most institutions that care for high risk patients offer comprehensive microbiology services that include both species-level identification as well as antifungal susceptibility testing of Candida spp. from blood and other normally sterile sites [ 100 ]. Unfortunately, the question “Why identify Candida to species?” is still posed by some healthcare providers and laboratorians [ 78 , 101 ]. Whereas lack of species identification might have been reasonable in the past when C. albicans was the dominant species and the choice of antifungal therapy was limited to amphotericin B [ 102 , 103 ], the present day situation is much more complicated [ 104 , 105 ]. There are now more infections with non- C. albicans species in most hospitals caring for high risk patients and the choice of antifungal agents now spans several different classes and formulations [ 105–111 ]. The increase in non- C. albicans infections is considered to be largely due to the widespread use of fluconazole which selects for those species that are intrinsically less susceptible to this agent than C. albicans [ 3 , 5 , 12 , 22 , 43 , 60 , 65 , 67 , 89 , 90 , 94 , 106 , 107 , 111–115 ]. Furthermore, species-specific resistance profiles are now well-recognized [ 8 , 112 ]. It is now clear that the in vitro patterns of antifungal susceptibility vary substantially among different Candida spp. (Table 5 ) and the IDSA and ESCMID guidelines for the treatment of candidiasis recommend that species-level identification be used as a surrogate for antifungal susceptibility testing for selecting empirical antifungal therapy [ 22 , 83 , 84 ]. Most recently the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) have published species-specific clinical breakpoints for the triazoles and echinocandins as well as species-specific epidemiological cutoff values (ECVs or ECOFFs) that help predict decreased susceptibility and potential resistance among those species for which clinical data are unavailable [ 100 ]. C. albicans and C. tropicalis are both susceptible to all of the available systemically active antifungal agents including fluconazole and the echinocandins [ 97 , 116 , 117 ]. Resistance to both the azole and echinocandin classes is very unusual for both C. albicans and C. tropicalis . Thus the more cost-effective agent, fluconazole, may be used in most situations reserving the echinocandins for the more seriously ill and unstable patient [ 21 , 22 , 112 ]. Likewise, C. glabrata and C. krusei are grouped together based on their decreased susceptibility to fluconazole [ 22 , 112 , 117 ]. The IDSA and ESCMID both recommend that an echinocandin be used for initial treatment of infections due to either of these species based on the excellent fungicidal activity of these agents against these two species [ 22 , 83 , 84 ]. De-escalation to fluconazole may be appropriate for infections with C. glabrata based on in vitro susceptibility results but is never appropriate for C. krusei [ 21 , 22 , 65 , 90 , 94 ]. Finally, C. parapsilosis requires specific identification for several reasons [ 118 ]: (i) due to decreased susceptibility to the echinocandins, it is recommended that fluconazole be used as initial therapy for C. parapsilosis infections [ 21 , 22 ]. As with C. albicans and C. tropicalis, C. parapsilosis is usually susceptible to fluconazole [ 117 ]; (ii) C. parapsilosis is notorious for causing catheter-related BSIs and both IDSA and ESCMID emphasize that catheters always be removed in C. parapsilosis infections [ 22 , 83 , 84 ]; (iii) when C. parapsilosis is found to be a cause of BSI, one must consider that there has been a lapse in proper catheter care that may require remedial instruction of healthcare personnel and the patient as appropriate [ 8 , 118 ]. This species frequently gains access to the bloodstream via contamination of the catheter hub and readily forms a biofilm within the lumen of the catheter [ 113 , 119 , 120 ]. Formation of biofilms confers significant resistance to antifungal therapy resulting in persistent infections despite what should be adequate antifungal therapy [ 118 ]. Whereas biofilm formation by C. parapsilosis is widely recognized, it is not the only species of Candida that is capable of forming biofilms on implanted biomaterials [ 121 , 122 ].

Species identification

Although the genus Candida contains over 200 different species, there are five major species ( C. albicans, C. tropicalis, C. parapsilosis, C. glabrata , and C. krusei ) that account for 95% to 97% of human infections (Table 4 ). In most instances the rank order is C. albicans > C. glabrata > C. parapsilosis > C. tropicalis > C. krusei ; however, the exact distribution may vary by geographic location and risk group [ 114 , 116 , 117 ]. For example, the fluconazole-resistant species C. glabrata and C. krusei cause a disproportionate number of infections in hematopoietic stem cell transplant (HSCT) recipients where azole prophylaxis is common [ 8 , 98 , 108 , 114 ]. C. parapsilosis , a species found on the skin of both patients and healthcare workers, causes catheter-related BSIs and is especially prominent among patients receiving TPN as well as in neonates [ 118 ]. C. glabrata is among the most common species associated with BSI among those greater than 70 years of age, whereas C. tropicalis causes infection in oncology patients receiving chemotherapy [ 8 , 108 , 111 ]. Colonization of high risk patients with certain species often predicts subsequent BSI with those species [ 8 ]. This has been demonstrated with C. glabrata, C. tropicalis , and C. krusei in HSCT recipients [ 123 , 124 ].

One of the reasons that the question “Why identify Candida to species?” has been posed is that the conventional methods for species identification are slow, cumbersome, often inaccurate and cannot provide species identification within the critical 12–24 h treatment window [ 125–127 ]. Conventional methods for yeast identification include the germ tube test, morphology on chromogenic and cornmeal agar, temperature tolerance, and biochemical methods such as Vitek (bioMerieux), API (bioMerieux), MicroScan (Beckman-Coulter) and others [ 125 , 127 , 128 ]. These tests require isolated colonies and incubation times of 48 to 72 h before a species identification is obtained. Even rapid “spot” tests for C. albicans (e.g., BactiCard Candida [Remel], Albi Quick [Hardy]) and C. glabrata (e.g., Rapid Trehalose Assimilation [Remel], Rapid Trehalase [Rosco]) require isolated colonies on agar medium before applying the rapid test for identification (delay of at least 24 h) [ 128 ]. Notably, these phenotypic methods may mis-identify rare or emerging species of Candida with clinically impactful consequences [ 23 , 125 , 127 ]. A very recent example is the misidentification of the MDR species C. auris as C. haemulonii or C. famata by the Vitek 2 and other phenotypic identification systems [ 129 ].

More recently, several new approaches to yeast identification have greatly improved the timeliness and accuracy of Candida species identification [ 56 , 125 , 127 ]. These include peptide nucleic acid (PNA)-fluorescent in situ hybridization (FISH), sequence-based identification, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) [ 56 , 130 ]. These methods have been applied directly to blood cultures and agar-based cultures and provide highly accurate identifications within 1 to 2h post culture [ 56 , 93 , 130 , 131 ].

The PNA-FISH tests (AdvanDx, Woburn, MA) are based on a fluorescein-labeled PNA probe that specifically detects C. albicans, C. tropicalis, C. parapsilosis, C. glabrata , and C. krusei in BCs by targeting species-specific rRNA sequences. Recent modifications to the probes and reagents have resulted in a second generation test ( Quick FISH TM ) that shortens the time to results from 90 minutes to 30 minutes. The test has been shown to have excellent sensitivity (99%), specificity (100%), positive predictive value (100%) and negative predictive value (99.3%) [ 132 ]. This approach may provide a time savings of 24 to 48 hours, compared with conventional laboratory methods used for identification.

Amplification-based methods are increasingly being applied to the post-culture identification of Candida and other yeasts [ 56 , 69 , 125 ]. Multiplex PCR platforms have been developed for the identification of Candida species in positive BC samples [ 133 ]. The FilmArray TM BC identification panel (BioFire, Salt Lake City, UT) and the xTAG TM fungal analyte-specific reagent assay (Luminex Molecular Diagnostics, Toronto, Canada) have demonstrated sensitivities and specificities of 100% and 99%, respectively, for the five most common species of Candida [ 56 , 133 ]. The FilmArray approach provides fully automated nucleic acid extraction, amplification and detection and has been FDA cleared for post-culture identification of bacteria and Candida species.

One of the most important advances in the post-culture identification of bacteria and fungi is that of MALDI-TOF MS [ 56 , 93 , 127 , 128 , 130 ]. MALDI-TOF MS uses species-specific patterns of peptides and protein masses to provide a rapid and reliable method for the identification of Candida , non- Candida yeasts, and some molds [ 56 , 93 , 128 , 130 ]. Studies have shown that this method is able to accurately and rapidly (10 min) identify Candida species from positive cultures, with a high concordance (>90%) in comparison to both conventional and molecular methods [ 9 , 56 , 93 , 128 , 130 ].

These molecular and proteomic approaches for identification of Candida from positive cultures improve the time to identification when compared to conventional methods and may be useful in antifungal stewardship interventions promoting optimal antifungal therapy with the most cost-effective antifungal agents, resulting in improved outcomes and significant antifungal savings for hospitals [ 9 , 24 , 41 , 56 , 93 ]. A cost minimization model was developed by Alexander et al. [ 134 ] to assess cost savings associated with implementation of the PNA-FISH test in a hospital with a rate of 40% for C. albicans candidemias and in which caspofungin was used over fluconazole for empiric treatment of IC. In their study they predicted that the use of the PNA-FISH test would result in a cost savings of approximately $1,800 (US $) per patient from reduced caspofungin use (switch to fluconazole in patients infected with C. albicans ), despite the fact that laboratory costs for performing the PNA-FISH test ($ 82.72 [US $] per test) exceeded those for the C. albicans screen test ($ 2.83 [US $]) or the Germ tube test ($ 4.42 [US $]). A subsequent study at the University of Maryland [ 135 ] used clinical data to show the effect of PNA-FISH testing for C. albicans and validated the decision model of Alexander et al. [ 134 ]. The Maryland investigators found that 43% of candidemias in their hospital were due to C. albicans and that the most pronounced effects of the PNA-FISH test was on caspofungin usage in patients with C. albicans fungemia. In this group, there was significant reduction in the usage of caspofungin (de-escalation to fluconazole) with a corresponding decrease in antifungal costs of $ 1,978 (US $) per patient [ 135 ]. The overall cost savings in reducing caspofungin usage surpassed the cost of the PNA-FISH test (net savings of $ 1,729 [US $] per patient) and led to the development of straightforward hospital-specific algorithms [ 135 ]. The disadvantages of these post-culture approaches for the diagnosis of IC is that they are still dependent on a positive BC, which may be negative in >50% of IC cases [ 58 ]. None of these methods are sensitive enough to reliably detect and identify Candida directly from clinical specimens but the improved accuracy and time to identification has clearly helped laboratories to provide species-level identification in a more clinically meaningful time frame [ 56 ].

Antifungal resistance

Although antifungal resistance is not as prevalent as antibacterial resistance, the overuse of ineffective, or unnecessary, antifungal therapy is a driving force for the emergence of antifungal resistance in Candida spp. just as it is for bacteria [ 18 , 27 , 28 , 60 , 136 ]. Indeed the CDC has specifically noted the increasing incidence of Candida infections due to azole-and echinocandin-resistant strains and considers it to be a “serious” public health threat that must be addressed through improved use of antifungal agents [ 137 ].

Presently, there are emerging resistance issues in three common species of Candida : C. glabrata, C. parapsilosis , and C. tropicalis. C. glabrata is a leading human fungal pathogen that causes life-threatening infections and poses a challenge to antifungal therapeutic options due to its reduced susceptibility to the azole antifungal agents and the ability to develop resistance to both azoles and echinocandins [ 29 ]. Resistance to fluconazole now approaches 30% of all C. glabrata isolates in many areas of the United States and echinocandin resistance ranges from 3% to 18% in institutions caring for high risk patients [ 18 , 27 , 28 , 60 , 136 ]. The SENTRY surveillance program has documented a steady increase in both the frequency of isolation of C. glabrata from BCs as well as an increasing resistance to both fluconazole and echinocandins in the United States over the past 19 years [ 29 , 32 , 138 ]. Similar findings have been reported from population-based surveillance in Denmark but not in other European countries [ 3 , 23 ] Recently, data from the CDC demonstrated a steady increase in echinocandin resistance among BSI isolates of C. glabrata in the Atlanta and Baltimore metropolitan areas [ 31 ]. Notably, 14.8% of fluconazole-resistant isolates of C. glabrata were also echinocandin-resistant and 36.2% of echinocandin-resistant isolates were also fluconazole-resistant. Co-resistance to both azoles and echinocandins has also been documented in C. glabrata isolates from both single center [ 27 , 28 , 136 ] and multicenter antifungal surveillance programs [ 33 , 139 ]. Emergence of azole- and echinocandin-resistance in other parts of the world is not as extensive as in the United States; however, increased rates of resistance to both classes of antifungal agents among non- C. albicans species has been noted in Denmark and France, and most recently in India [ 26 , 34 , 35 ].

Among the different Candida species, C. glabrata appears to be unique in its ability to acquire and express mutations that result in phenotypic and clinical resistance [ 29 , 30 ]. This may be due to the haploid nature of the organism resulting in the ability to rapidly express a variety of resistance mutations [ 27–30 , 136 , 139 ].Exposure to fluconazole reliably induces CDR efflux pumps resulting in pan-azole resistance [ 29 , 112 ]. Similarly, exposure to echinocandins has been shown to be a predictor of mutations in the FKS genes encoding for the glucan synthase enzyme complex (target for echinocandin activity) and thus echinocandin resistance in three major U.S. transplant centers [ 27 , 28 , 136 ]. In each case elevated echinocandin MICs and a characteristic FKS mutation correlated with echinocandin treatment failure.

C. parapsilosis is most notable for causing BSI in neonates and patients receiving TPN [ 98 , 118 ]. Infection with C. parapsilosis is almost always associated with indwelling vascular catheters [ 118 ]. The decreased susceptibility of C. parapsilosis to echinocandins is a well-known concern [ 117 ], with some centers reporting a decreased prevalence of C. albicans in favor of C. parapsilosis as a cause of candidiasis in patients exposed to echinocandins [ 91 ]. In light of these concerns both IDSA and ESCMID have recommended the use of fluconazole coupled with prompt catheter removal in patients with C. parapsilosis BSI [ 22 , 83 , 84 ]. Whereas resistance to fluconazole has not been a concern with C. parapsilosis [ 97 , 116 ], a report from Finland suggested that fluconazole resistance in C. parapsilosis may emerge following drug pressure in the form of fluconazole prophylaxis [ 140 ]. Most recently the fluconazole resistance rate among US isolates of C. parapsilosis was 4.0% for the time period 2006–2011 (range 0.0% to 16.9%) [ 117 ].

C. tropicalis is generally susceptible to both azoles and echinocandins [ 5 , 117 ], and the use of these agents has been associated with a decrease in incidence of BSIs due to C. tropicalis in US cancer centers [ 108 , 111 ]. It must be noted, however, that resistance to fluconazole and other azoles appears to be increasing among clinical isolates of C. tropicalis outside of the United States, with ranges of 7% in Denmark [ 3 ] to 40% in Japan [ 141 ]. In the United States, fluconazole resistance among isolates of C. tropicalis ranges from 2.4% to 4.8% with cross-resistance between fluconazole, posaconazole, and voriconazole detected in isolates from all regions of the country [ 117 ]. Notably, a recent survey found that in contrast to previous years, echinocandin resistance was detected among U.S. C. tropicalis BSI isolates from 2013[ 142 ]. Previous reports have shown a step-wise progression of echinocandin resistance associated with the development of FKS mutations in isolates of C. tropicalis from patients being treated with an echinocandin [ 143–145 ]. Recent data from India indicates that C. tropicalis was the most frequent cause of candidemia in patients in the intensive care unit (ICU) and is an emerging MDR (resistance to fluconazole and echinocandins) species of Candida in that country [ 26 ].

The development of resistance to azoles and echinocandins among three common species of Candida is cause for concern. Because genes encoding for antifungal resistance in Candida are not passed from organism-to-organism [ 115 , 146 ], control of such resistance should be more easily addressed than is the case with bacteria. Antifungal resistance in Candida is clearly related to the exposure of infecting and colonizing strains to specific antifungal agents [ 27 , 28 , 60 , 115 , 136 , 147 ]. As such the efforts of antifungal stewardship to reduce inappropriate use of antifungal agents should also impact the emergence of resistance at a given institution. Application of rapid species-specific diagnostic tests should make these efforts even more effective allowing specific antifungal therapy to be administered only to those patients that are infected.

Diagnosis

It is widely recognized that early diagnosis of candidiasis is difficult [ 58 , 59 , 68 ]. The clinical signs and symptoms are non-specific and often appear late in the course of infection. Given the critically ill nature of most high-risk patients, invasive diagnostic procedures may be considered too risky and the entire diagnostic process is negatively impacted by the lack of sensitive and minimally invasive assays [ 9 , 56 ].

Physical examination

With regard to the physical examination of patients at high risk for Candida infections there are a few important features that should be kept in mind. In the non-neutropenic patient a dilated eye examination to detect Candida endophthalmitis can serve to guide therapy in patients with established candidemia and is a process measure that is monitored in several stewardship efforts [ 22 , 75 ]. In some instances intravitreal antifungal therapy and/or vitrectomy may be indicated. Furthermore, evidence of eye involvement should prompt the addition of an antifungal agent that has ocular penetration, such as fluconazole or flucytosine, especially if the patient is being treated with an echinocandin, a class of agents for which ocular penetration is limited [ 21 , 22 ]. Daily examination of the skin may also reveal lesions suggestive of hematogenous dissemination [ 148 ]. Biopsy of such lesions can provide a rapid and definitive diagnosis of candidiasis (or other infectious etiologies) [ 149 , 150 ]. Given the serious nature of candidal endocarditis, auscultation of the heart for murmurs should also be performed as a matter of routine [ 22 , 83 , 84 ]. Finally, examination of any sites of intravascular catheterization, and consideration of early removal in septic patients, is important given the frequency of Candida as a cause of catheter-associated infection [ 21 , 22 ].

Blood cultures

Blood cultures (BCs) remain an established approach to the diagnosis of candidiasis [ 22 , 83 , 84 ]. This is despite the fact that BCs have always been considered to be too slow and insensitive to serve as an early diagnostic method [ 56 , 58 , 62 , 151 ]. It is increasingly apparent that as many as one-third of patients with candidiasis never have a positive BC and even when positive, species-level results may not be available for 48 to 72 h or longer [ 16 , 58 , 152 ]. Notably, in a review of 415 autopsy-proven cases of candidiasis, Clancy and Nguyen [ 58 ] demonstrated that BCs were positive in only 38% of cases. This low yield of BCs was confirmed by Avni et al. [ 153 ] who reported a pooled BC positivity rate of 38% in a meta-analysis of 10 studies for the diagnosis of IC. Cultures of blood and other clinical specimens may also be rendered falsely negative by the use of prophylactic or empiric antifungal therapy further confounding efforts to establish a firm diagnosis [ 154 , 155 ]. Despite these negative features, BCs remain at the heart of care guidelines for candidiasis in hospitalized individuals [ 22 , 83 ]. Because contemporary BC methods demonstrate variable sensitivity, especially at low concentrations of Candida in the blood sample, current practice is to serially collect multiple aerobic and anaerobic BC specimens over 24 to 48 h [ 9 , 75 , 128 , 156 ]. It should be noted that the fungal BC bottles available for both the BacT/Alert (bioMerieux) and Bactec (Becton Dickinson) BC systems are superior to the standard aerobic BC bottles for detection of Candida spp. [ 157 , 158 ]. This is especially important for the detection of C. glabrata with the Bactec system [ 3 , 23 , 157 ]. It is now understood that the information required to limit mortality and the emergence of antifungal resistance is time-critical and as such rapid culture-independent diagnostic tests are required to complement BCs in the management of high risk patients [ 56 , 58 , 62 , 81 , 151 ].

Culture-independent diagnostic tests

Culture-independent tests for candidiasis may be used as biomarkers to assess the risk of having candidal infection thereby facilitating preemptive therapy [ 18 , 56 , 58 , 59 , 62 ]. Among the potential biomarkers that may be detected by various methods, there are several that are commercially available in the United States or Europe either as send out tests (reference laboratory) or in a kit format to be performed on-site in the hospital laboratory (Table 6 ). The biomarkers and associated test methods to be covered in this review are the Fungitell β-D-glucan (BDG; Associates of Cape Cod, Inc.) test, the Platelia mannan/anti-mannan (BioRad Laboratories) immunoassays, two real-time PCR assays available from Quest ( www.questdiagnostics.com ) and Viracor ( www.viracoribt.com ) reference laboratories, respectively,as well as the SeptiFast real-time PCR test (Roche Molecular Systems) and the T2Candida panel (T2Biosystems) [ 151 , 154 , 159 ].

Table 6.

Commercially available culture-independent diagnostic test for candidiasis.

     
Test Vendor/manufacturer Specimen type Limit of detection Sens Spec Comments 
β-D-glucan (Fungitell) a Assoc. Cape Cod, Inc. Serum or plasma 80 pg/ml 75.3 85.0  FDA cleared; not Specific for Candida 
Mannan/Antimannan b Platelia Serum ≥0.5 ng/ml (mannan) 83.0 86.0 Not available in US; not FDA cleared 
Real-time PCR c Quest Diagnostics Serum 1−350 CFU/ml NA NA Reference laboratory; not FDA cleared 
Real-time PCR d Viracor.IBT Serum or plasma ≤1 CFU/ml 80.0 70.0 Reference laboratory; not FDA cleared 
SeptiFast Real-Time PCR e Roche Diagnostics Whole blood 30−100 CFU/ml 61.0 99.0 Not available in US; not FDA cleared; Whole blood tested after extraction 
T2Candida f T2Biosystems Whole blood 1-3 CFU/ml 91.1 99.4 FDA cleared; whole blood tested without extraction 
     
Test Vendor/manufacturer Specimen type Limit of detection Sens Spec Comments 
β-D-glucan (Fungitell) a Assoc. Cape Cod, Inc. Serum or plasma 80 pg/ml 75.3 85.0  FDA cleared; not Specific for Candida 
Mannan/Antimannan b Platelia Serum ≥0.5 ng/ml (mannan) 83.0 86.0 Not available in US; not FDA cleared 
Real-time PCR c Quest Diagnostics Serum 1−350 CFU/ml NA NA Reference laboratory; not FDA cleared 
Real-time PCR d Viracor.IBT Serum or plasma ≤1 CFU/ml 80.0 70.0 Reference laboratory; not FDA cleared 
SeptiFast Real-Time PCR e Roche Diagnostics Whole blood 30−100 CFU/ml 61.0 99.0 Not available in US; not FDA cleared; Whole blood tested after extraction 
T2Candida f T2Biosystems Whole blood 1-3 CFU/ml 91.1 99.4 FDA cleared; whole blood tested without extraction 

a Karageorgopoulos et al. [ 160 ].

b Mikulska et al. [ 161 ].

c Quest Diagnostics website ( www.questdiagnostics.com ).

d Nguyen et al. [ 152 ].

e Chang et al. [ 162 ].

f Mylonakis et al. [ 159 ].

BDG (1-3, β-D-glucan) is an important component of the cell wall of Candida, Aspergillus , and many other pathogenic fungi, and thus is nonspecific [ 160 ]. Although BDG is not immunogenic, the fact that it can be found circulating in the bloodstream of patients with invasive fungal infection (IFI) has been exploited for use diagnostically as a surrogate marker for infection [ 56 , 68 ]. The Fungitell assay is a commercially-available CE-marked and FDA-cleared assay for the detection of BDG in serum [ 56 , 160 ]. The detection system is based on the activation of a BDG-sensitive proteolytic coagulation cascade, the components of which are purified from the horseshoe crab [ 56 ]. The assay can measure picogram quantities of BDG and has been used to demonstrate the presence of the polysaccharide in the serum of patients with candidiasis and aspergillosis. The test does not detect cryptococcosis or mucormycosis (organisms lack 1-3, β-D-glucan), nor does it provide species-level identification for either Candida or Aspergillus [ 56 ]. The BDG test has been associated with a large number of false-positive results in high risk patient populations, limiting its value for screening purposes [ 58 , 68 , 160 ]. Causes of false-positive BDG results include Gram-positive BSI, excess manipulation of the sample prior to testing, hemolysis, hemodialysis with cellulose membranes, patients treated with intravenous immunoglobulins, albumin, coagulation factors or plasma protein factor, or patients exposed to gauze or other materials that contain glucans [ 58 , 68 , 160 ]. A recent meta-analysis of 16 studies measuring serum or plasma BDG for the diagnosis of candidiasis reported pooled sensitivity and specificity values of 75.3% and 85.0%, respectively [ 160 ] (Table  6 ). Although the BDG test may be performed in a hospital-based laboratory, it is a send out test for the vast majority of institutions resulting in a turn-around time (TAT) for results measured in days rather than hours.

Despite a long history of serologic tests for Candida antigens and antibodies, the only immunologic markers that have shown any utility for Candida diagnosis are anti-mannan antibodies and mannan antigen [ 56 , 161 ]. Detection of mannan is complicated by rapid clearance from the patients’ sera and binding by anti-mannan antibody. In order to optimize the detection of mannan in serum the antigen-antibody complexes must be disassociated. The Platelia Candida antigen and antibody tests are commercially-available (CE-marked in Europe; not FDA-cleared) enzyme immunoassays for detection of serum levels of mannan antigen and anti-mannan antibodies respectively [ 56 , 161 ]. Studies have shown that whereas the diagnosis of candidiasis cannot be made using a single test for antibodies or antigen alone, a strategy based on detection of mannanemia and anti-mannan antibodies may prove to be the most useful approach [ 161 ]. In a recent meta-analysis Mikulska et al. [ 161 ] reported a combined mannan/anti-mannan sensitivity and specificity for candidiasis diagnosis of 83.0% and 86.0%, respectively (Table  6 ). The separate sensitivities and specificities were 58% and 93% respectively, for mannan antigen alone and 59% and 83%, respectively, for anti-mannan antibodies alone. It should be noted that these results, while specific for the Candida genus, do not provide species-level information required to guide specific antifungal therapy. Importantly, it appears that regular (at least twice weekly) serum sampling is critical to achieving an early diagnosis of candidiasis using mannan/anti-mannan testing [ 161 ]. It should also be noted that the sensitivity of both mannan and anti-mannan tests varies for different species of Candida and is highest for C. albicans , followed by C. glabrata and C. tropicalis [ 161 ].

PCR-based assays are currently the most commonly employed molecular-based approach to fungal diagnostics, and real-time PCR has shown promising results [ 56 , 62 , 151 , 153 ]. The potential advantages of real-time PCR include a rapid (hours) time to results for some targets and the flexibility of the platform. This approach employs a closed system that provides simultaneous amplification and detection and limits the risk of assay contamination. The method of detection is often fluorescence-based and allows for quantitation.

PCR-amplified Candida -specific DNA has been recovered from blood, serum, plasma, tissues and cerebrospinal fluid [ 56 , 153 , 154 , 159 ]. In addition to the selection of the optimal specimen type, important procedural considerations need to be taken for removal of contaminating nonfungal DNA, breaking fungal cells for DNA extraction, and prevention of the introduction of contaminating fungal DNA as well as minimizing the destruction of target DNA [ 56 , 153 ]. The most frequently employed targets for the diagnosis of IC are the multicopy broad-range panfungal genes such as the 18S, 5.8S, and 28S ribosomal sequences, and the intergenic transcribed spacer (ITS) regions within the rRNA gene cluster [ 56 , 62 , 153 ].

PCR detection methods vary widely but most laboratory developed tests (LDT) employ capture probes in an ELISA format. Recent developments such as real-time PCR, gene chip technology, and the coupling of nanotechnology with magnetic resonance detection will facilitate the broad use of this technology [ 56 , 62 , 153 , 154 , 159 , 162 ].

The major impediment to the application of PCR to the diagnosis of candidiasis has been the lack of standardization, variable analytical sensitivity, and the need for nucleic acid extraction and purification from clinical samples [ 62 , 151 ]. A range of sensitivity of 77% to 100% and specificity of 66% to 100% has been reported [ 153 ]. Among several reasons for the reported low levels of sensitivity include requirements for nucleic acid extraction and the use of optical methods of detection resulting in excessively high limits of detection (LOD) [ 56 , 62 , 153 , 154 ]. In a systematic meta-analysis evaluating PCR assays for the diagnosis of candidiasis, pooled analysis of 54 studies and almost 5,000 patients found that the optimal conditions for the diagnosis of candidiasis using PCR were (i) the use of whole blood, (ii) a multi-copy target, and (iii) a LOD of <10 CFU per ml of blood [ 153 ]. Under these conditions the pooled sensitivity and specificity of PCR in diagnosing candidiasis was 95% and 92%, respectively. Importantly, PCR-based tests for Candida DNA in blood are negative in most subjects with gastrointestinal colonization with Candida species and the specificity of these tests is quite high [ 153 , 159 , 162 ].

Aside from using consensus to develop a standardized molecular assay for the diagnosis of candidiasis, standardization may also be achieved by either a centralization model whereby a molecular test is offered and performed by a publically available reference laboratory (Table 6 ) or by commercialization of a molecular test to be performed on-site [ 62 ]. Commercialization of molecular tests not only standardizes the method but also facilitates large-scale “real world” clinical validation, leading to the implementation of the molecular test for clinical use [ 62 ].

Presently there are only three commercially available amplification-based molecular tests that have been evaluated for use in the diagnosis of IC directly from the clinical specimen in either the United States (Viracor Candida Real-Time PCR Panel [Viracor-IBT] and the T2Candida Panel [T2Biosystems]) or Europe (LightCycler SeptFast Test [Roche Diagnostics] and the T2Candida Panel [T2Biosystems]) [ 56 , 151 , 152 , 154 , 159 , 162 ]. Other direct from blood sample platforms that include Candida are commercially available outside the United States.: SepsiTest (Molzym, Bremen, Germany), MagicPlex (Seegene, Seoul, Korea), VYOO (SIRS-Lab, Jena, Germany), PLEX-ID (Abbott Molecular, Carlsbad, CA, USA). The published clinical evaluations of these methods are weighted heavily towards the detection and identification of bacteria and they are not included in this review [ 163–171 ].

The Viracor ( www.viracoribt.com ) reference laboratory offers a real-time PCR panel for the detection of the five major species of Candida ( C. albicans, C. tropicalis, C. parapsilosis, C. glabrata and C. krusei ) in serum or plasma with an LOD of <1 CFU/ml. This is a LDT and is not FDA cleared. The Viracor Candida Real-Time PCR Panel targets the ITS1 and ITS2 rRNA sequences, requires nucleic acid extraction and purification, and employs fluorescence-based detection. In a single center clinical evaluation, the sensitivity and specificity of the Viracor Panel for the diagnosis of IC was 80% and 70%, respectively [ 152 ]. Notably the Viracor Panel was more sensitive in diagnosing deep-seated candidiasis than candidemia (89% versus 59%, respectively). Likewise, PCR was more sensitive than BC among patients with deep-seated candidiasis (88% versus 17%), demonstrating the importance of this approach as a compliment to BC. Although the in-laboratory turn around time (TAT) for the Viracor Panel is reported to be within 6 to 8 hours, the send out nature of the test means that the actual TAT for reporting results to the clinician is measured in days rather than hours.

Another real-time PCR test for IC is offered in the U.S. by Quest Diagnostics reference laboratories ( www.questdiagnostics.com ). Similar to the Viracor Candida Real-Time PCR Panel, the Quest Candida DNA, Qualitative, Real-Time PCR test is not FDA-cleared, requires nucleic acid extraction and purification from serum and detects the five most common species of Candida . The LOD for the Quest Candida test is reported to be <1 to 350 CFU/ml depending on the species. Thus far the clinical sensitivity and specificity of this test has not been reported in the literature.

The Roche SeptiFast real-time PCR platform has been extensively evaluated in Europe where it is CE-marked but it has not been cleared by the FDA for use in the United States [ 151 , 162 ]. SeptiFast uses real-time multiplex PCR to detect nucleic acids extracted from whole blood for five species of Candida as well as 19 species of bacteria and Aspergillus fumigatus . The diagnostic probes for PCR target the internal transcribed sequences situated between the 18S and 5.6S fungal rRNA and the amplification product is detected by the use of fluorescent probes. Subsequently, a melting curve analysis is employed to identify the species. The LOD for Candida using SeptiFast ranges from 30 CFU/ml ( C. albicans, C. parapsilosis and C. krusei ) to 100 CFU/ml ( C. glabrata ) (162). When performed in the laboratory the TAT for a single test is approximately 6 h. In a meta-analysis Chang et al. [ 162 ] reported a pooled sensitivity of 61% and a specificity of 99% for the detection of Candida in whole blood following extraction (Table 6 ).

The T2Candida Panel (T2Biosystems) is a CE-marked and FDA cleared rapid diagnostic approach that employs a proprietary formulation that enables inhibition-free target amplification of the multicopy ITS2 (internal transcribed spacer region 2) region of the Candida genome. The resulting amplicons are detected using nanoparticles coated with oligonucleotide capture probes to enable sensitive and specific detection directly in whole blood without the need for culture or nucleic acid extraction steps [ 154 , 159 ]. The T2Candida Panel uses T2MR (T2Magnetic Resonance) relaxometry to measure the magnetic properties of the water molecules in the specimen (signal amplification) and not just the amplified target to achieve improved sensitivity in complex clinical samples [ 154 ]. Results from formal verification studies of the T2Candida Panel showed an LOD of 1 to 3 CFU/ml of blood with results available as fast as 3 h compared to >48 h for BC [ 154 , 159 ]. In a recently completed 1,801-patient clinical trial the T2Candida Panel showed a sensitivity and specificity for the detection of candidemia of 91.1% and 99.4%, respectively [ 159 ] (Table 6 ). The T2Candida Panel allows for the detection and identification of the five major species of Candida ( C. albicans, C. tropicalis, C. parapsilosis, C. glabrata , and C. krusei ). The test is completely automated and requires <5 minutes of hands on time. In the pivotal clinical trial [ 159 ], the T2Candida Panel had a median time to detection and species identification of 4.2 hours, compared to BC-based diagnostic approaches which returned a median time to detection and species identification of 129 hours. The median time to a negative result for the T2Candida Panel was 4.4 hours, compared to a median time to result of ≥120 hours for BC-based methods.

The ability to rapidly detect the presence of Candida spp. directly in whole blood offers exciting new possibilities for the early diagnosis and management of candidiasis in high-risk patients [ 56 , 62 ]. A potential strategy for the use of non-culture-based methods for the diagnosis of candidiasis is to stratify patients according to risk (Tables 2 , 3 , and 7 ) and conduct prospective screening using the rapid test coupled with other diagnostic tests (e.g., BCs, imaging studies) [ 39 , 40 , 57 , 59 , 80 ]. This strategy should facilitate earlier species-level diagnosis thereby allowing targeted preemptive antifungal therapy. A highly sensitive and specific test should also help to reduce empirical therapy with concomitant reduction in selection pressure for resistance as well as cost savings for the hospital [ 59 , 60 ]. With a rapid and simple test the opportunity for monitoring the response to antifungal therapy may also be possible. One obvious question that must be addressed is whether or not monitoring has a significant impact on patient management and survival. It is also important to understand that rapid diagnostic tests have been shown to have little clinical or economic impact in the absence of an active antimicrobial stewardship effort [ 55 , 81 ].

Table 7.

Risk stratification and the predictive value of rapid diagnostic test for candidiasis.

     Predictive value (%) a 
Test Vendor/Manufacturer Sens/Spec (%) Prevalence of Disease (%) PPV NPV 
 
Fungitell (BDG) Assoc. Cape Cod, Inc. 75.3/85.0 9.3 99.4 
   21.1 98.5 
   10 35.7 96.8 
   30 68.2 88.8 
Mannan/antimannan Platelia 83.0/86.0 11.0 99.6 
   24.0 99.0 
   10 39.7 97.9 
   30 71.8 92.2 
SeptiFast Real-time PCR Roche Diagnostics 61.0/99.0 54.5 99.2 
   77.5 98.0 
   10 87.1 95.8 
   30 96.3 85.6 
T2Candida T2Biosystems 91.1/99.4 75.0 99.8 
   88.5 99.6 
   10 94.8 99.0 
   30 98.6 96.3 
     Predictive value (%) a 
Test Vendor/Manufacturer Sens/Spec (%) Prevalence of Disease (%) PPV NPV 
 
Fungitell (BDG) Assoc. Cape Cod, Inc. 75.3/85.0 9.3 99.4 
   21.1 98.5 
   10 35.7 96.8 
   30 68.2 88.8 
Mannan/antimannan Platelia 83.0/86.0 11.0 99.6 
   24.0 99.0 
   10 39.7 97.9 
   30 71.8 92.2 
SeptiFast Real-time PCR Roche Diagnostics 61.0/99.0 54.5 99.2 
   77.5 98.0 
   10 87.1 95.8 
   30 96.3 85.6 
T2Candida T2Biosystems 91.1/99.4 75.0 99.8 
   88.5 99.6 
   10 94.8 99.0 
   30 98.6 96.3 

a PPV, positive predictive value; NPV, negative predictive value.

Prevalence and predictive values

As with most diagnostic tests, the performance of culture-independent tests for the diagnosis of candidiasis is impacted by the prevalence of infection in the tested population and is likely to be most useful in patients at the highest risk of infection [ 59 ] (Table 7 ). In Table 7 we demonstrate the positive (PPV) and negative (NPV) predictive values of four tests for the diagnosis of candidiasis in populations for which the prevalence of infection ranged from 2% to 30%. Whereas both antigen (BDG and mannan/anti-mannan) and molecular (SeptiFast and T2Candida) based tests have a high (>98%) NPV when applied to populations with a low (2% to 5%) prevalence of disease, the T2Candida panel also pairs a high NPV (96.3% to 99.0%) with a high PPV (94.8% to 98.6%) in populations in which the prevalence of disease is 10% to 30% (Table 7 ). Thus in an ICU where the baseline prevalence of candidaemia is 5%, a patient exposed to four different antibacterial agents would have an estimated risk of infection of ∼35% (Table 3 ) and a T2Candida test performed on that patient would have a PPV of 98.6% and a NPV of 96.3% (Table 7 ). These results are clearly sufficient to identify the patients that warrant early preemptive therapy and the identification of the infecting organisms to species facilitates pathogen-targeted therapy. Because the risk for candidiasis in hospital is a continuum (Table 2 ), serial testing of T2Candida-negative high risk patients may be necessary to achieve optimal results [ 57 ].

It has been suggested that NPVs of 96%–98% may allow IFI to be excluded and render empiric antifungal treatment unnecessary [ 57 , 59 ]. Indeed, Barnes et al. [ 57 ] showed that a diagnostic-driven (as opposed to therapeutic-driven) strategy (pan-fungal PCR) both optimized pre-emptive treatment of IFI in a high risk hematology population and also decreased the empiric use of antifungal agents. This diagnostic-driven approach reduced antifungal expenditures by more than that required for the implementation of the diagnostic test, proving that the strategy was cost-effective. Importantly, it was also demonstrated that withholding therapy in PCR-negative patients reduced the utilization of antifungal therapy, without increasing morbidity or mortality.

Modifiable factors that impact mortality

The consequences of nosocomial candidiasis are severe. Patients with candidemia have been shown to be at two-fold greater risk of death in hospital than are patients with noncandidal BSI [ 172 ]. Estimates of the mortality attributable to nosocomial candidiasis have been reported from retrospective matched cohort studies conducted in single institutions and in the context of population-based studies [ 42 , 44 , 45 , 48 , 50 ]. Data from these studies suggest that candidiasis is associated with substantial excess (attributable) mortality ranging from 10% to 49%[ 42 ]. Furthermore, these data demonstrate that candidemia carries no less risk of death during hospitalization today than it did 20 years ago [ 42 , 44 , 50 , 173 ], despite the introduction of new antifungal agents with superior safety, spectrum, and potency against most species of Candida [ 105 , 174 , 175 ].

Treatment of candidiasis is often found to be inadequate based on several factors that may be amenable to antifungal stewardship efforts [ 10–15 , 18 , 20 , 176 ]. These modifiable factors include delay in administration of therapy, treatment with an agent to which the organism is resistant, inadequate dose or duration of treatment, failure to properly manage indwelling vascular catheters (source control), or absence of any treatment at all. Several studies have shown that a delay in the initiation of adequate antifungal therapy of >12–24h was independently associated with mortality in patients with candidemia [ 11 , 14–16 , 176–178 ]. In a study that specifically addressed the delay in diagnosis implicit in the use of BC, Taur et al. [ 16 ] found that in cancer patients with candidaemia, the time from blood culture collection to positivity (the incubation period) was associated with in-hospital mortality. The mortality rate increased by 1.025-fold for every hour of BC incubation. A 24 h delay in BC positivity effectively doubles the risk of death.

Fluconazole is arguably the most commonly prescribed systemically active antifungal agent [ 175 , 179 , 180 ]. Although the clinical efficacy of fluconazole in the treatment of candidemia is well established [ 90 ], Garey et al. [ 12 ] have demonstrated a high prevalence of suboptimal dosing of fluconazole given empirically or after Candida spp. identification was documented. These authors found that 78% of patients infected with C. glabrata received fluconazole at a dose that was lower than the recommended 12mg/kg/day [ 12 ]. Such dosing practices are likely to impact both clinical outcomes and resistance rates.

A population-based study of candidemia found that removal of vascular catheters, in addition to receipt of at least five days of antifungal treatment, was independently associated with decreased risk of both early and late mortality [ 99 ]. Likewise, Labelle et al. [ 13 ] found that treatment-related factors including retention of central venous catheters (CVCs) and inadequate initial fluconazole dosing were associated with increased hospital mortality in patients with Candida BSIs. These data suggest that optimization of initial antifungal therapy and removal of CVCs (source control) may improve the outcomes of patients with Candida BSI and should be closely monitored by the antifungal stewardship team.

Despite numerous barriers to improving outcomes in patients with candidiasis, the way forward may be to consider the guidelines presented in the Surviving Sepsis Campaign [ 181 ]. Sepsis as a whole is estimated at more than 500,000 cases annually in the United States, with a reported mortality rate of 35% to 60%[ 182–184 ]. Notably, sepsis is not uncommon among patients with candidiasis ranging from 10% to 48% of infected patients [ 176 , 185–191 ]. A recent report by Guillamet et al. [ 192 ] found that among 2,597 consecutive patients with a positive BC and severe sepsis or septic shock, 10.2% had BCs positive for Candida spp. Wisplinghoff et al. [ 191 ] demonstrated that BSI caused by Candida spp. initiates a severe inflammatory response leading to a clinical course comparable to that of sepsis due to S. aureus , but with an even higher mortality. Given that each hour of delay in the administration of antibiotics and/or antifungal agents is associated with an 8% increase in the mortality rate [ 183 , 190 , 193 ], the Surviving Sepsis Campaign developed evidence-based practice guidelines with the intent of standardizing the approach to sepsis in order to reduce mortality [ 181 , 183 , 184 ]. The current international guidelines for the management of sepsis recommend, in addition to hemodynamic resuscitation and source control, timely (within 1h) empiric combination therapy targeting likely bacterial and/or fungal pathogens [ 181 , 183 ]. In recognition of the role that Candida may play in severe sepsis/septic shock, the guidelines also recommend the use of fungal biomarkers, if available, when candidiasis is considered [ 181 ]. Consistent with these recommendations, Kollef et al. [ 176 ] have underscored the importance of source control (catheter removal) and empiric therapy in septic patients with candidiasis. Delayed (>24 h) antifungal treatment and failure to achieve timely source control were independently associated with a greater risk of hospital mortality (AOR, 33.75 and 77.40, respectively).

Process issues and outcomes with antifungal stewardship

The process of antifungal stewardship must support early intervention and appropriate administration of antifungal therapy. To that end it is imperative that rapid diagnostic tests be implemented such that results are available 24 h per day, 7 days a week [ 69 , 85 , 194 ]. Tests should be performed as soon as the specimen arrives in the laboratory and should not be batched or sent to an outside laboratory. To do so would be to significantly reduce the impact of the rapid test in directing antifungal therapy [ 194 ]. Just as important as timely performance of each test is the timely reporting of results, which constitute “critical values” in patient care [ 69 , 75 , 194 ]. In addition to rapid test performance and reporting, efforts should also be made to minimize the “hang time” from order to administration of antifungal therapy [ 75 ]. Thus far reports detailing the impact of antifungal stewardship in optimizing the treatment of candidaemia have largely focused on these process issues and have documented improvements in rates of ophthalmologic examinations, selection and timing of appropriate antifungal agents and catheter removal [ 75 , 76 , 85 ]. Although these studies have not been sufficiently powered to show any improvement in outcomes, a recent study by Guarascio et al. [ 77 ] demonstrated that an active antifungal surveillance program resulted in a significant decrease in the median days of caspofungin therapy (4.0 days to 2.0 days) with a potential cost savings of $1,013 (US $) per patient. Likewise, Aitken et al. [ 55 ] estimated that in a single hospital the use of rapid diagnostic test, such as T2Candida, on the day of BC collection provided a species-level result that decreased the use of echinocandins by 3,136 to 6,078 fewer doses annually per 5,000 high risk patients with a potential cost savings of approximately $700,000 to $1.4 million (US $) per year. Similarly, Bilir et al. [ 195 ] developed a one-year decision-tree model to estimate hospital costs and effects (candidemia-related deaths) of using the T2Candida Panel versus BC alone, accounting for disease prevalence, distribution of Candida species, test characteristics (sensitivity, specificity, time to result), antifungal medication use, and differential length of stay (LOS) in hospital and mortality by time to appropriate treatment initiation. Using assumptions based on the contemporary literature, the annual cost for testing and treating 5,000 high-risk patients with the baseline BC-based strategy was estimated at $12,298,598 (US $) compared to $ 6, 440,150 (US $) in the T2Candida-based diagnostic strategy for a potential annual savings of $5,858,448 (47.6%; US $). The estimated savings per patient with candidemia was $ 26,887 (US $), a 48.8% reduction in hospital costs. Rapid species detection and identification and earlier treatment associated with the T2Candida strategy resulted in fewer deaths, reducing the overall mortality by 31.7 deaths (60.6%; BC, 52.3 deaths; T2Candida, 20.6 deaths). Given these improvements, a diagnostic strategy that couples the use of a rapid culture independent diagnostic test with high PPV and NPV (Table 7 ) with an active antifungal stewardship effort may be favored over BC alone in both cost effectiveness/cost-avoidance and outcomes analysis.

In order to inform both clinicians and hospital administration of the value of antifungal stewardship the team must identify those outcomes that are important to monitor and provide feedback at regular intervals [ 24 , 89 ]. Thus, changes in the epidemiology and antifungal susceptibility of the target pathogens should be documented as well as TAT for rapid diagnostic tests, clinical outcomes and length of stay in infected patients [ 24 , 69 , 75 ]. Given the often specialized needs of these high- risk patients, the antifungal stewardship team should also facilitate continuity of care and discharge planning [ 24 ]. This is especially important if the patient is to be discharged on oral or parenteral antifungal therapy. In the later instance catheter management will be of critical importance in the successful management of the infection.

Conclusions

The clinical and economic impact of IC places it among the most deadly and expensive HAIs encountered worldwide. Inappropriate use of antifungal agents not only exposes many uninfected patients to the expense and toxicity of unnecessary antifungal therapy, it also is a direct contributor to an ever increasing burden of antifungal resistance. Furthermore, it is now apparent that effective treatment of IC is almost always delayed by more than 24h with resultant increase in mortality and healthcare costs. Thus it is imperative that efforts be made to improve the management of IC to ensure that the right antifungal agent is administered to the right patient, at the proper dose and in a timely fashion. This must be the overriding goal of antifungal stewardship. Thus far antifungal stewardship efforts have been shown to improve the process of treating IC by attending to improved dosing and duration of treatment, catheter management and limiting the use of inappropriate prophylaxis and empiric treatment. Unfortunately, detecting those patients that merit antifungal treatment early enough in the course of infection to impact on mortality and LOS in hospital is still limited by the use of slow and ineffective means of diagnosing infection. Antifungal stewardship focused on IC can take advantage of new, rapid, culture-independent testing approaches to the diagnosis of candidiasis in high risk patients. These efforts will improve care by increasing the awareness of candidiasis, improve diagnostic efforts and focus therapy on those patients who are most likely to benefit from it. In the process, antifungal stewardship and rapid diagnosis should both save lives and decease the costs of antifungal therapy in the hospital. By decreasing inappropriate antifungal use, antifungal stewardship should also reduce selection pressure for resistance among clinical isolates of Candida.

The authors thank Daniel J. Diekema, MD, for a critical review of the manuscript. Michael A. Pfaller is an employee of T2Biosystems; Grant support (Astellas, Merck, Methylgene, Pfizer, Seachaid, Synexis, Cidara); and serves on the advisory boards of Astellas and Merck. Mariana Castanheira has received research and educational grants in 2012–2014 from Achaogen, Actelion, Affinium, American Proficiency Institute (API), AmpliPhi Bio, Anacor, Astellas, AstraZenica, Basilea, BioVersys, Cardeas, Cempra, Cerexa, Cubist, Daiichi, Dipexium, Durata, Fedora, Forrest Research Institute, Furiex, Genetech, GlaxoSmithKline, Janssen, Johnson & Johnson, Medpace, Meiji Seika Kaisha, Melinta, Merck, Methylgene, Nabriva, Nanosphere, Novartis, Pfizer, Polyphor, Remplex, Roche, Seachaid, Shionogi, Synthes, The Medicines Co., Theravance, ThermoFisher, Venatorx, Vertex, Waterloo and some other corporations. Some JMI employees are advisors/consultants for Astellas, Cubist, Pfizer, Cempra, Cerexa-Forrest, and Theravance. In regards to speakers’ bureaus and stock options, there are none to declare.

Declaration of interest

The authors have no conflicts of interest to declare. The authors alone are responsible for the content and the writing of the paper.

References

1.
Brown
GD
Denning
DW
Gow
NA
et al
Hidden killers: human fungal infections
Science translational medicine
 
2012
4
165rv13
2.
Pfaller
MA
Diekema
DJ
Epidemiology of invasive mycoses in North America
Crit Rev Microbiol
 
2010
36
1
53
3.
Arendrup
MC
Bruun
B
Christensen
JJ
et al
National surveillance of fungemia in Denmark (2004 to 2009)
J Clin Microbiol
 
2011
49
325
334
4.
Azie
N
Neofytos
D
Pfaller
M
et al
The PATH (Prospective Antifungal Therapy) Alliance registry and invasive fungal infections: Update 2012
Diagn Microbiol Infect Dis
 
2012
73
293
300
5.
Cleveland
AA
Farley
MM
Harrison
LH
et al
Changes in incidence and antifungal drug resistance in candidemia: results from population-based laboratory surveillance in Atlanta and Baltimore
Clin Infect Dis
 
2012
55
1352
1361
2008-2011
6.
Milazzo
L
Peri
AM
Mazzali
C
et al
Candidaemia observed at a university hospital in milan (northern Italy) and review of published studies from 2010 to 2014
Mycopathologia
 
2014
178
227
241
7.
Pfaller
MA
Diekema
DJ
Epidemiology of invasive candidiasis: A persistent public health problem
Clin Microbiol Rev
 
2007
20
133
163
8.
Pfaller
MA
Diekema
DJ
Calderone
RA
Clancy
CJ
  The epidemiology of invasive candidasis
Candida and Candidiasis
 
2012
2nd ed
Washington, D.C. USA
American Society for Microbiology
449
480
9.
Alexander
BD
Pfaller
MA
Contemporary tools for the diagnosis and management of invasive mycoses
Clin Infect Dis
 
2006
43
S15
S27
10.
Azoulay
E
Dupont
H
Tabah
A
et al
Systemic antifungal therapy in critically ill patients without invasive fungal infection*
Crit Care Med
 
2012
40
813
822
11.
Garey
KW
Rege
M
Pai
MP
et al
Time to initiation of fluconazole therapy impacts mortality in patients with candidemia: a multi-institutional study
Clin Infect Dis
 
2006
43
25
31
12.
Garey
KW
Pai
MP
Suda
KJ
et al
Inadequacy of fluconazole dosing in patients with candidemia based on Infectious Diseases Society of America (IDSA) guidelines
Pharmacoepidemiol Drug Saf
 
2007
16
919
927
13.
Labelle
AJ
Micek
ST
Roubinian
N
et al
Treatment-related risk factors for hospital mortality in Candida bloodstream infections
Crit Care Med
 
2008
36
2967
2972
14.
Morrell
M
Fraser
VJ
Kollef
MH
Delaying the empiric treatment of Candida bloodstream infection until positive blood culture results are obtained: A potential risk factor for hospital mortality
Antimicrob Agents Chemother
 
2005
49
3640
3645
15.
Parkins
MD
Sabuda
DM
Elsayed
S
et al
Adequacy of empirical antifungal therapy and effect on outcome among patients with invasive Candida species infections
J Antimicrob Chemother
 
2007
60
613
618
16.
Taur
Y
Cohen
N
Dubnow
S
et al
Effect of antifungal therapy timing on mortality in cancer patients with candidemia
Antimicrob Agents Chemother
 
2010
54
184
190
17.
Tabah
A
Koulenti
D
Laupland
K
et al
Characteristics and determinants of outcome of hospital-acquired bloodstream infections in intensive care units: the EUROBACT International Cohort Study
Intensive Care Med
 
2012
38
1930
1945
18.
Drgona
L
Khachatryan
A
Stephens
J
et al
Clinical and economic burden of invasive fungal diseases in Europe: focus on pre-emptive and empirical treatment of Aspergillus and Candida species
Eur J Clin Microbiol. Infect Dis
 
2014
33
7
21
19.
Lee
W
Liew
Y
Chlebicki
MP
et al
An observational study on early empiric versus culture-directed antifungal therapy in critically ill with intra-abdominal sepsis
Crit Care Res Pract
 
2014
2014
479413
20.
Arnold
HM
Micek
ST
Shorr
AF
et al
Hospital resource utilization and costs of inappropriate treatment of candidemia
Pharmacotherapy
 
2010
30
361
368
21.
Koehler
P
Tacke
D
Cornely
OA
Our 2014 approach to candidaemia
Mycoses
 
2014
57
581
583
22.
Pappas
PG
Kauffman
CA
Andes
D
et al
Clinical practice guidelines for the management of candidiasis: 2009 update by the Infectious Diseases Society of America
Clin Infect Dis
 
2009
48
503
535
23.
Arendrup
MC
Sulim
S
Holm
A
et al
Diagnostic issues, clinical characteristics, and outcomes for patients with fungemia
J Clin Microbiol
 
2011
49
3300
3308
24.
Ananda-Rajah
MR
Slavin
MA
Thursky
KT
The case for antifungal stewardship
Curr Op Infect Dis
 
2012
25
107
115
25.
Vincent
JL
Rello
J
Marshall
J
et al
International study of the prevalence and outcomes of infection in intensive care units
JAMA
 
2009
302
2323
2329
26.
Chakrabarti
A
Sood
P
Rudramurthy
SM
et al
Incidence, characteristics and outcome of ICU-acquired candidemia in India
Intensive Care Med
 
2015
41
285
295
27.
Alexander
BD
Johnson
MD
Pfeiffer
CD
et al
Increasing echinocandin resistance in Candida glabrata: Clinical failure correlates with presence of FKS mutations and elevated minimum inhibitory concentrations
Clin. Infect Dis
 
2013
56
1724
1732
28.
Beyda
ND
John
J
Kilic
A
et al
  FKS Mutant Candida glabrata : Risk factors and outcomes in patients with candidemia
Clin Infect Dis
 
2014
59
819
825
29.
Pfaller
MA
Castanheira
M
Lockhart
SR
et al
  Candida glabrata : Multidrug resistance and increased virulence in a major opportunistic fungal pathogen
Curr Fungal Infect Rep
 
2012
6
154
164
30.
Castanheira
M
Woosley
LN
Messer
SA
et al
Frequency of fks mutations among Candida glabrata isolates from a 10-year global collection of bloodstream infection isolates
Antimicrob Agents Chemother
 
2014
58
577
580
31.
Pham
CD
Iqbal
N
Bolden
CB
et al
The role of FKS mutations in C. glabrata : MIC values, echinocandin resistance and multidrug resistance
Antimicrob Agents Chemother
 
2014
58
4690
4696
32.
Diekema
DJ
Messer
SA
Brueggemann
AB
et al
Epidemiology of candidemia: 3-year results from the emerging infections and the epidemiology of Iowa organisms study
J Clin Microbiol
 
2002
40
1298
1302
33.
Pfaller
MA
Castanheira
M
Lockhart
SR
et al
Frequency of decreased susceptibility and resistance to echinocandins among fluconazole-resistant bloodstream isolates of Candida glabrata
J Clin Microbiol
 
2012
50
1199
1203
34.
Arendrup
MC
Perlin
DS
Echinocandin resistance: an emerging clinical problem
?
Current Op Infect Dis
 
2014
27
484
492
35.
Dannaoui
E
Desnos-Ollivier
M
Garcia-Hermoso
D
et al
  Candida spp. with acquired echinocandin resistance, France, 2004–2010
Emerg Infect Dis
 
2012
18
86
90
36.
Hidron
AI
Edwards
JR
Patel
J
et al
NHSN annual update: antimicrobial-resistant pathogens associated with healthcare-associated infections: Annual summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2006–2007
Infect Control Hosp Epidemiol
 
2008
29
996
1011
37.
Blumberg
HM
Jarvis
WR
Soucie
JM
et al
Risk factors for candidal bloodstream infections in surgical intensive care unit patients: The NEMIS prospective multicenter study. The National Epidemiology of Mycosis Survey
Clin Infect. Dis
 
2001
33
177
186
38.
Chen
SC
Marriott
D
Playford
EG
et al
Candidaemia with uncommon Candida species: predisposing factors, outcome, antifungal susceptibility, and implications for management
Clin Microbiol Infect
 
2009
15
662
669
39.
Prentice
HG
Kibbler
CC
Prentice
AG
Towards a targeted, risk-based, antifungal strategy in neutropenic patients
Br J Haematol
 
2000
110
273
284
40.
Wenzel
RP
Gennings
C
Bloodstream infections due to Candida species in the intensive care unit: identifying especially high-risk patients to determine prevention strategies
Clin Infect Dis
 
2005
41
S389
S393
41.
Ashley
ED
Drew
R
Johnson
M
et al
Cost of Invasive Fungal Infections in the Era of New Diagnostics and Expanded Treatment Options
Pharmacotherapy
 
2012
32
890
901
42.
Falagas
ME
Apostolou
KE
Pappas
VD
Attributable mortality of candidemia: A systematic review of matched cohort and case-control studies
Eur J Clin Microbiol Infect Dis
 
2006
25
419
425
43.
Garey
KW
Turpin
RS
Bearden
DT
et al
Economic analysis of inadequate fluconazole therapy in non-neutropenic patients with candidaemia: A multi-institutional study
Int J Antimicrob Agents
 
2007
29
557
562
44.
Gudlaugsson
O
Gillespie
S
Lee
K
et al
Attributable mortality of nosocomial candidemia, revisited
Clin Infect Dis
 
2003
37
1172
1177
45.
Hassan
I
Powell
G
Sidhu
M
et al
Excess mortality, length of stay and cost attributable to candidaemia
J Infect
 
2009
59
360
365
46.
Menzin
J
Lang
KM
Friedman
M
et al
Excess mortality, length of stay, and costs associated with serious fungal infections among elderly cancer patients: findings from linked SEER-Medicare data
Value in health : the journal of the International Society for Pharmacoeconomics and Outcomes Research
 
2005
8
140
148
47.
Menzin
J
Meyers
JL
Friedman
M
et al
The economic costs to United States hospitals of invasive fungal infections in transplant patients
Am J Infect Control
 
2011
39
e15
20
48.
Morgan
J
Meltzer
MI
Plikaytis
BD
et al
Excess mortality, hospital stay, and cost due to candidemia: a case-control study using data from population-based candidemia surveillance
Infect Control Hosp Epidemiol
 
2005
26
540
547
49.
Shorr
AF
Gupta
V
Sun
X
et al
Burden of early-onset candidemia: Analysis of culture-positive bloodstream infections from a large U.S. database
Crit Care Med
 
2009
37
2519
2526
50.
Wey
SB
Mori
M
Pfaller
MA
et al
Hospital-acquired candidemia. The attributable mortality and excess length of stay
Arch Intern. Med
 
1988
148
2642
2645
51.
Zilberberg
MD
Kollef
MH
Arnold
H
et al
Inappropriate empiric antifungal therapy for candidemia in the ICU and hospital resource utilization: A retrospective cohort study
BMC Infect Dis
 
2010
10
150
52.
Ananda-Rajah
MR
Cheng
A
Morrissey
CO
et al
Attributable hospital cost and antifungal treatment of invasive fungal diseases in high-risk hematology patients: an economic modeling approach
Antimicrob Agents Chemother
 
2011
55
1953
1960
53.
Gagne
JJ
Breitbart
RE
Maio
V
et al
Costs associated with candidemia in a hospital setting
P&T
 
2006
31
586
619
54.
Fridkin
SK
Candidemia is costly–plain and simple
Clin Infect Dis
 
2005
41
1240
2141
55.
Aitken
SL
Beyda
ND
Shah
DN
et al
Clinical practice patterns in hospitalized patients at risk for invasive candidiasis: role of antifungal stewardship programs in an era of rapid diagnostics
Ann Pharmacother
 
2014
48
683
690
56.
Arvanitis
M
Anagnostou
T
Fuchs
BB
et al
Molecular and nonmolecular diagnostic methods for invasive fungal infections
Clin Microbiol Rev
 
2014
27
490
526
57.
Barnes
RA
White
PL
Bygrave
C
et al
Clinical impact of enhanced diagnosis of invasive fungal disease in high-risk haematology and stem cell transplant patients
J Clin Pathol
 
2009
62
64
69
58.
Clancy
CJ
Nguyen
MH
Finding the "missing 50%" of invasive candidiasis: how nonculture diagnostics will improve understanding of disease spectrum and transform patient care
Clin Infect Dis
 
2013
56
1284
1292
59.
Clancy
CJ
Nguyen
MH
Undiagnosed invasive candidiasis: incorporating non-culture diagnostics into rational prophylactic and preemptive antifungal strategies
Expert Rev Anti Infect Ther
 
2014
12
731
734
60.
Hull
CM
Purdy
NJ
Moody
SC
Mitigation of human-pathogenic fungi that exhibit resistance to medical agents: can clinical antifungal stewardship help
?
Future Microbiol
 
2014
9
307
325
61.
O'Brien
DJ
Gould
IM
Maximizing the impact of antimicrobial stewardship: the role of diagnostics, national and international efforts
Current Op Infect Dis
 
2013
26
352
358
62.
Zhang
SX
Enhancing molecular approaches for diagnosis of fungal infections
Future Microbiol
 
2013
8
1599
1611
63.
Dellit
TH
Owens
RC
McGowan
JE
Jr.
et al
Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America guidelines for developing an institutional program to enhance antimicrobial stewardship
Clin Infect Dis
 
2007
44
159
177
64.
Leuthner
KD
Doern
GV
Antimicrobial stewardship programs
J Clin Microbiol
 
2013
51
3916
3920
65.
Ruhnke
M
Antifungal stewardship in invasive Candida infections
Clin Microbiol Infect
 
2014
20
11
18
66.
Standiford
HC
Chan
S
Tripoli
M
et al
Antimicrobial stewardship at a large tertiary care academic medical center: cost analysis before, during, and after a 7-year program
Infect Control Hosp Epidemiol
 
2012
33
338
345
67.
Valerio
M
Rodriguez-Gonzalez
CG
Munoz
P
et al
Evaluation of antifungal use in a tertiary care institution: antifungal stewardship urgently needed
J Antimicrob Chemother
 
2014
69
1993
1999
68.
Ostrosky-Zeichner
L
Invasive mycoses: diagnostic challenges
Am J Med
 
2012
125
S14
24
69.
Perez
KK
Olsen
RJ
Musick
WL
et al
Integrating rapid pathogen identification and antimicrobial stewardship significantly decreases hospital costs
Arch Pathol Lab Med
 
2013
137
1247
1254
70.
Hanson
KE
Pfeiffer
CD
Lease
ED
et al
beta-D-glucan surveillance with preemptive anidulafungin for invasive candidiasis in intensive care unit patients: a randomized pilot study
PLoS One
 
2012
7
e42282
71.
Ostrosky-Zeichner
L
Pappas
PG
Shoham
S
et al
Improvement of a clinical prediction rule for clinical trials on prophylaxis for invasive candidiasis in the intensive care unit
Mycoses
 
2011
54
46
51
72.
Ostrosky-Zeichner
L
Shoham
S
Vazquez
J
et al
MSG-01: A randomized, double-blind, placebo-controlled trial of caspofungin prophylaxis followed by preemptive therapy for invasive candidiasis in high-risk adults in the critical care setting
Clin Infect Dis
 
2014
58
1219
1226
73.
Posteraro
B
De Pascale
G
Tumbarello
M
et al
Early diagnosis of candidemia in intensive care unit patients with sepsis: a prospective comparison of (1–>3)-beta-D-glucan assay, Candida score, and colonization index
Crit Care
 
2011
15
R249
74.
Apisarnthanarak
A
Yatrasert
A
Mundy
LM
Thammasat University Antimicrobial Stewardship T. Impact of education and an antifungal stewardship program for candidiasis at a Thai tertiary care center
Infect Control Hosp Epidemiol
 
2010
31
722
727
75.
Reed
EE
West
JE
Keating
EA
et al
Improving the management of candidemia through antimicrobial stewardship interventions
Diagn Microbiol Infect Dis
 
2014
78
157
161
76.
Antworth
A
Collins
CD
Kunapuli
A
et al
Impact of an antimicrobial stewardship program comprehensive care bundle on management of candidemia
Pharmacotherapy
 
2013
33
137
143
77.
Guarascio
AJ
Slain
D
McKnight
R
et al
A matched-control evaluation of an antifungal bundle in the intensive care unit at a university teaching hospital
Int J Clin Pharm
 
2013
35
145
148
78.
Schultz
V
Colombo
AL
Pasqualotto
AC
Invasive candidosis: contrasting the perceptions of infectious disease physicians and intensive care physicians
Rev Soc Bras Med Trop
 
2013
46
466
471
79.
Bauer
KA
West
JE
Balada-Llasat
JM
et al
An antimicrobial stewardship program's impact with rapid polymerase chain reaction methicillin-resistant Staphylococcus aureus/.Σ συερυα blood culture test in patients with S. aureus bacteremia
Clin Infect Dis
 
2010
51
1074
1080
80.
McLintock
LA
Jordanides
NE
Allan
EK
et al
The use of a risk group stratification in the management of invasive fungal infection: a prospective validation
Br J Haematol
 
2004
124
403
404
81.
Caliendo
AM
Gilbert
DN
Ginocchio
CC
et al
Better tests, better care: improved diagnostics for infectious diseases
Clin Infect Dis
 
2013
57
S139
170
82.
Nivoix
Y
Launoy
A
Lutun
P
et al
Adherence to recommendations for the use of antifungal agents in a tertiary care hospital
J Antimicrob Chemother
 
2012
67
2506
2513
83.
Cornely
OA
Bassetti
M
Calandra
T
et al
ESCMID* guideline for the diagnosis and management of Candida diseases 2012: non-neutropenic adult patients
Clin Microbiol Infect
 
2012
18
19
37
84.
Ullmann
AJ
Akova
M
Herbrecht
R
et al
ESCMID guideline for the diagnosis and management of Candida diseases 2012: adults with haematological malignancies and after haematopoietic stem cell transplantation (HCT)
Clin Microbiol Infect
 
2012
18
53
67
85.
Mondain
V
Lieutier
F
Hasseine
L
et al
A 6-year antifungal stewardship programme in a teaching hospital
Infection
 
2013
41
621
628
86.
Ben-Ami
R
Halaburda
K
Klyasova
G
et al
A multidisciplinary team approach to the management of patients with suspected or diagnosed invasive fungal disease
J Antimicrob Chemother
 
2013
68
iii25
33
87.
Cisneros
JM
Neth
O
Gil-Navarro
MV
et al
Global impact of an educational antimicrobial stewardship programme on prescribing practice in a tertiary hospital centre
Clin Microbiol Infect
 
2014
20
82
88
88.
Davey
P
Brown
E
Charani
E
et al
Interventions to improve antibiotic prescribing practices for hospital inpatients
Cochrane Database Syst Rev
 
2013
4
CD003543
89.
van Buul
LW
Sikkens
JJ
van Agtmael
MA
et al
Participatory action research in antimicrobial stewardship: a novel approach to improving antimicrobial prescribing in hospitals and long-term care facilities
J Antimicrob Chemother
 
2014
69
1734
1741
90.
Craver
CW
Tarallo
M
Roberts
CS
et al
Cost and resource utilization associated with fluconazole as first-line therapy for invasive candidiasis: a retrospective database analysis
Clin Ther
 
2010
32
2467
2477
91.
Fournier
P
Schwebel
C
Maubon
D
et al
Antifungal use influences Candida species distribution and susceptibility in the intensive care unit
J Antimicrob Chemother
 
2011
66
2880
2886
92.
Vandijck
D
Blot
S
Labeau
S
et al
Candidemia in critically ill patient: An analysis of daily antifungal therapy related costs
J de Mycologie Medicale
 
2008
18
96
99
93.
Huang
AM
Newton
D
Kunapuli
A
et al
Impact of rapid organism identification via matrix-assisted laser desorption/ionization time-of-flight combined with antimicrobial stewardship team intervention in adult patients with bacteremia and candidemia
Clin Infect Dis
 
2013
57
1237
1245
94.
Shah
DN
Yau
R
Weston
J
et al
Evaluation of antifungal therapy in patients with candidaemia based on susceptibility testing results: implications for antimicrobial stewardship programmes
J Antimicrob Chemother
 
2011
66
2146
2151
95.
MacFadden
DR
Leis
JA
Mubareka
S
et al
The opening and closing of empiric windows: the impact of rapid microbiologic diagnostics
Clin Infect Dis
 
2014
59
1199
1200
96.
Wey
SB
Mori
M
Pfaller
MA
et al
Risk factors for hospital-acquired candidemia. A matched case-control study
Arch Intern Med
 
1989
149
2349
2353
97.
Pfaller
MA
Moet
GJ
Messer
SA
et al
  Candida bloodstream infections: Comparison of species distributions and antifungal resistance patterns in community-onset and nosocomial isolates in the SENTRY Antimicrobial Surveillance Program, 2008–2009
Antimicrob Agents Chemother
 
2011
55
561
566
98.
Pfaller
MA
Neofytos
D
Diekema
D
et al
Epidemiology and outcomes of candidemia in 3648 patients: data from the Prospective Antifungal Therapy (PATH Alliance(R)) registry, 2004–2008
Diagn Microbiol Infect Dis
 
2012
74
323
331
99.
Almirante
B
Rodriguez
D
Park
BJ
et al
Epidemiology and predictors of mortality in cases of Candida bloodstream infection: results from population-based surveillance, Barcelona, Spain, from 2002 to 2003
J Clin Microbiol
 
2005
43
1829
1835
100.
Pfaller
MA
Diekema
DJ
Progress in antifungal susceptibility testing of Candida spp. by use of Clinical and Laboratory Standards Institute broth microdilution methods, 2010 to 2012
J Clin Microbiol
 
2012
50
2846
2856
101.
Schelenz
S
Barnes
RA
Kibbler
CC
et al
Standards of care for patients with invasive fungal infections within the United Kingdom: a national audit
J Infect
 
2009
58
145
153
102.
Chandrasekar
P
Management of invasive fungal infections: a role for polyenes
J Antimicrob Chemother
 
2011
66
457
465
103.
Ostrosky-Zeichner
L
Marr
KA
Rex
JH
et al
Amphotericin B: time for a new "gold standard"
Clin Infect Dis
 
2003
37
415
425
104.
Kontoyiannis
DP
Invasive mycoses: strategies for effective management
Am J Med
 
2012
125
S25
S38
105.
Ostrosky-Zeichner
L
Casadevall
A
Galgiani
JN
et al
An insight into the antifungal pipeline: selected new molecules and beyond
Nat Rev Drug Discov
 
2010
9
719
727
106.
Falagas
ME
Roussos
N
Vardakas
KZ
Relative frequency of albicans and the various non- albicans Candida spp among candidemia isolates from inpatients in various parts of the world: a systematic review
Int J Infect Dis
 
2010
14
e954
e966
107.
Guinea
J
Global trends in the distribution of Candida species causing candidemia
Clin Microbiol Infect
 
2014
20
5
10
108.
Hachem
R
Hanna
H
Kontoyiannis
D
et al
The changing epidemiology of invasive candidiasis: Candida glabrata and Candida krusei as the leading causes of candidemia in hematologic malignancy
Cancer
 
2008
112
2493
2499
109.
Johnson
MD
Kleinberg
M
Danziger
L
et al
Pharmacoeconomics of antifungal pharmacotherapy–challenges and future directions
Expert Opin Pharmacother
 
2005
6
2617
2632
110.
Maschmeyer
G
Patterson
TF
Our 2014 approach to breakthrough invasive fungal infections
Mycoses
 
2014
57
645
651
111.
Sipsas
NV
Lewis
RE
Tarrand
J
et al
Candidemia in patients with hematologic malignancies in the era of new antifungal agents (2001-2007): Stable incidence but changing epidemiology of a still frequently lethal infection
Cancer
 
2009
115
4745
4752
112.
Pfaller
MA
Antifungal drug resistance: mechanisms, epidemiology, and consequences for treatment
Am J Med
 
2012
125
S3
S13
113.
Diekema
DJ
Pfaller
MA
Nosocomial candidemia: an ounce of prevention is better than a pound of cure
Infect Control Hosp Epidemiol
 
2004
25
624
626
114.
Pfaller
MA
Andes
DR
Diekema
DJ
et al
Epidemiology and outcomes of invasive candidiasis due to non-albicans species of Candida in 2,496 patients: data from the Prospective Antifungal Therapy (PATH) registry 2004-2008
PLoS One
 
2014
9
e101510
115.
Hof
H
Is there a serious risk of resistance development to azoles among fungi due to the widespread use and long-term application of azole antifungals in medicine
?
Drug Resist Updat
 
2008
11
25
31
116.
Castanheira
M
Messer
SA
Jones
RN
et al
Activity of echinocandins and triazoles against a contemporary (2012) worldwide collection of yeast and moulds collected from invasive infections
Int J Antimicrob Agents
 
2014
44
320
326
117.
Pfaller
MA
Jones
RN
Castanheira
M
Regional data analysis of Candida non-albicans strains collected in United States medical sites over a 6-year period, 2006-2011
Mycoses
 
2014
57
602
611
118.
Trofa
D
Gacser
A
Nosanchuk
JD
  Candida parapsilosis , an emerging fungal pathogen
Clin Microbiol Rev
 
2008
21
606
625
119.
Clark
TA
Slavinski
SA
Morgan
J
et al
Epidemiologic and molecular characterization of an outbreak of Candida parapsilosis bloodstream infections in a community hospital
J Clin Microbiol
 
2004
42
4468
4472
120.
Levin
AS
Costa
SF
Mussi
NS
et al
  Candida parapsilosis fungemia associated with implantable and semi-implantable central venous catheters and the hands of healthcare workers
Diagn Microbiol Infect Dis
 
1998
30
243
249
121.
Chandra
J
Kuhn
DM
Mukherjee
PK
et al
Biofilm formation by the fungal pathogen Candida albicans: development, architecture, and drug resistance
J Bacteriol
 
2001
183
5385
5394
122.
Douglas
LJ
Candida biofilms and their role in infection
Trends Microbiol
 
2003
11
30
36
123.
Pfaller
M
Cabezudo
I
Koontz
F
et al
Predictive value of surveillance cultures for systemic infection due to Candida species
Eur J Clin Microbiol
 
1987
6
628
633
124.
Sandford
GR
Merz
WG
Wingard
JR
et al
The value of fungal surveillance cultures as predictors of systemic fungal infections
J Infect Dis
 
1980
142
503
509
125.
Borman
AM
Szekely
A
Palmer
MD
et al
Assessment of accuracy of identification of pathogenic yeasts in microbiology laboratories in the United Kingdom
J Clin Microbiol
 
2012
50
2639
2644
126.
Fernandez
J
Erstad
BL
Petty
W
et al
Time to positive culture and identification for Candida blood stream infections
Diagn Microbiol Infect Dis
 
2009
64
402
407
127.
Pfaller
MA
Woosley
LN
Messer
SA
et al
Significance of molecular identification and antifungal susceptibility of clinically significant yeasts and moulds in a global antifungal surveillance program
Mycopathologia
 
2012
174
259
271
128.
Marcos
JY
Pincus
DH
Fungal diagnostics: review of commercially available methods
Methods Mol Biol
 
2013
968
25
54
129.
Kathuria
S
Singh
PK
Sharma
C
et al
Multidrug-resistant Candida auris misidentified as Candida haemulonii: characterization by matrix-assisted laser desorption ionization-time of flight mass spectrometry and DNA sequencing and its antifungal susceptibility profile variability by Vitek 2, CLSI broth microdilution, and Etest method
J Clin Microbiol
 
2015
53
1823
1830
130.
Buchan
BW
Ledeboer
NA
Advances in identification of clinical yeast isolates by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry
J Clin Microbiol
 
2013
51
1359
1366
131.
Stone
NR
Gorton
RL
Barker
K
et al
Evaluation of PNA-FISH yeast traffic light for rapid identification of yeast directly from positive blood cultures and assessment of clinical impact
J Clin Microbiol
 
2013
51
1301
1302
132.
Hall
L
Le Febre
KM
Deml
SM
et al
Evaluation of the Yeast Traffic Light PNA FISH probes for identification of Candida species from positive blood cultures
J Clin Microbiol
 
2012
50:
1446
1448
133.
Griffin
AT
Hanson
KE
Update on fungal diagnostics
Curr Infect Dis Rep
 
2014
16
415
134.
Alexander
BD
Ashley
ED
Reller
LB
et al
Cost savings with implementation of PNA FISH testing for identification of Candida albicans in blood cultures
Diagn Microbiol Infect Dis
 
2006
54
277
282
135.
Forrest
GN
Mankes
K
Jabra-Rizk
MA
et al
Peptide nucleic acid fluorescence in situ hybridization-based identification of Candida albicans and its impact on mortality and antifungal therapy costs
J Clin Microbiol
 
2006
44
3381-3383
136.
Shields
RK
Nguyen
MH
Press
EG
et al
Caspofungin MICs correlate with treatment outcomes among patients with Candida glabrata invasive candidiasis and prior echinocandin exposure
Antimicrob Agents Chemother
 
2013
57
3528
3535
137.
CDC
Antibiotic Resistance Threats in the United States
 
2013
138.
Matsumoto
E
Boyken
L
Tendolkar
S
et al
Candidemia surveillance in Iowa: emergence of echinocandin resistance
Diagn Microbiol Infect Dis
 
2014
79
205
208
139.
Zimbeck
AJ
Iqbal
N
Ahlquist
AM
et al
  FKS mutations and elevated echinocandin MIC values among Candida glabrata isolates from U.S. population-based surveillance
Antimicrob Agents Chemother
 
2010
54
5042
5047
140.
Sarvikivi
E
Lyytikainen
O
Soll
DR
et al
Emergence of fluconazole resistance in a Candida parapsilosis strain that caused infections in a neonatal intensive care unit
J Clin Microbiol
 
2005
43
2729
2735
141.
Chong
Y
Shimoda
S
Yakushiji
H
et al
Fatal candidemia caused by azole-resistant Candida tropicalis in patients with hematological malignancies
J Infect Chemother
 
2012
18
741
746
142.
Pfaller
MA
Rhomberg
PR
Messer
SA
et al
Isavuconazole, micafungin and eight comparator antifungal agents susceptibility profiles for common and uncommon opportunistic fungi collected in 2013: Temporal analysis of antifungal drug resistance using CLSI species-specific interpretive criteria
Diagn Microbiol Infect Dis
 
2015
82
303
313
143.
Garcia-Effron
G
Kontoyiannis
DP
Lewis
RE
et al
Caspofungin-resistant Candida tropicalis strains causing breakthrough fungemia in patients at high risk for hematologic malignancies
Antimicrob Agents Chemother
 
2008
52
4181
4813
144.
Jensen
RH
Johansen
HK
Arendrup
MC
Stepwise development of a homozygous S80P substitution in Fks1p, conferring echinocandin resistance in Candida tropicalis
Antimicrob Agents Chemother
 
2013
57
614
617
145.
Pasquale
T
Tomada
JR
Ghannoun
M
et al
Emergence of Candida tropicalis resistant to caspofungin
J Antimicrob Chemother
 
2008
61
219
146.
Ghannoum
MA
Rice
LB
Antifungal agents: Mode of action, mechanisms of resistance, and correlation of these mechanisms with bacterial resistance
Clin Microbiol Rev
 
1999
12
501
517
147.
Ostrosky-Zeichner
L
  Candida glabrata and FKS mutations: witnessing the emergence of the true multidrug-resistant Candida
Clin Infect Dis
 
2013
56
1733
1734
148.
Bae
GY
Lee
HW
Chang
SE
et al
Clinicopathologic review of 19 patients with systemic candidiasis with skin lesions
Int J Dermatol
 
2005
44
550
555
149.
Guarner
J
Incorporating pathology in the practice of infectious disease: myths and reality
Clin Infect Dis
 
2014
59
1133
1141
150.
Guarner
J
Brandt
ME
Histopathologic diagnosis of fungal infections in the 21st century
Clin Microbiol Rev
 
2011
24
247
280
151.
Liesenfeld
O
Lehman
L
Hunfeld
KP
et al
Molecular diagnosis of sepsis: New aspects and recent developments
Eur J Microbiol Immunol.(Bp)
 
2014
4
1
25
152.
Nguyen
MH
Wissel
MC
Shields
RK
et al
Performance of Candida real-time polymerase chain reaction, beta-D-glucan assay, and blood cultures in the diagnosis of invasive candidiasis
Clin Infect Dis
 
2012
54
1240
1248
153.
Avni
T
Leibovici
L
Paul
M
PCR diagnosis of invasive candidiasis: systematic review and meta-analysis
J Clin Microbiol
 
2011
49
665
670
154.
Neely
LA
Audeh
M
Phung
NA
et al
T2 magnetic resonance enables nanoparticle-mediated rapid detection of candidemia in whole blood
Science Translational Medicine
 
2013
5
182ra54
155.
Riedel
S
Eisinger
SW
Dam
L
et al
Comparison of BD Bactec Plus Aerobic/F medium to VersaTREK Redox 1 blood culture medium for detection of Candida spp. in seeded blood culture specimens containing therapeutic levels of antifungal agents
J Clin Microbiol
 
2011
49
1524
1529
156.
Lee
A
Mirrett
S
Reller
LB
et al
Detection of bloodstream infections in adults: how many blood cultures are needed?
J Clin Microbiol
 
2007
45
3546
3548
157.
Meyer
MH
Letscher-Bru
V
Jaulhac
B
et al
Comparison of Mycosis IC/F and plus Aerobic/F media for diagnosis of fungemia by the bactec 9240 system
J Clin Microbiol
 
2004
42
773
777
158.
Mirrett
S
Reller
LB
Petti
CA
et al
Controlled clinical comparison of BacT/ALERT standard aerobic medium with BACTEC standard aerobic medium for culturing blood
J Clin Microbiol
 
2003
41
2391
2394
159.
Mylonakis
E
Clancy
CJ
Ostrosky-Zeichner
L
et al
T2 magnetic resonance assay for the rapid diagnosis of candidemia in whole blood: a clinical trial
Clin Infect Dis
 
2015
60
892
899
160.
Karageorgopoulos
DE
Vouloumanou
EK
Ntziora
F
et al
beta-D-glucan assay for the diagnosis of invasive fungal infections: a meta-analysis
Clin Infect Dis
 
2011
52
750
770
161.
Mikulska
M
Calandra
T
Sanguinetti
M
et al
The use of mannan antigen and anti-mannan antibodies in the diagnosis of invasive candidiasis: recommendations from the Third European Conference on Infections in Leukemia
Crit Care
 
2010
14
R222
162.
Chang
SS
Hsieh
WH
Liu
TS
et al
Multiplex PCR system for rapid detection of pathogens in patients with presumed sepsis - a systemic review and meta-analysis
PLoS One
 
2013
8
e62323
163.
Carrara
L
Navarro
F
Turbau
M
et al
Molecular diagnosis of bloodstream infections with a new dual-priming oligonucleotide-based multiplex PCR assay
J Med Microbiol
 
2013
62
1673
1679
164.
Fitting
C
Parlato
M
Adib-Conquy
M
et al
DNAemia detection by multiplex PCR and biomarkers for infection in systemic inflammatory response syndrome patients
PLoS One
 
2012
7
e38916
165.
Haag
H
Locher
F
Nolte
O
Molecular diagnosis of microbial aetiologies using SepsiTest in the daily routine of a diagnostic laboratory
Diagn Microbiol Infect Dis
 
2013
76
413
418
166.
Jordana-Lluch
E
Carolan
HE
Gimenez
M
et al
Rapid diagnosis of bloodstream infections with PCR followed by mass spectrometry
PLoS One
 
2013
8
e62108
167.
Leitner
E
Kessler
HH
Spindelboeck
W
et al
Comparison of two molecular assays with conventional blood culture for diagnosis of sepsis
J Microbiol Methods
 
2013
92
253
255
168.
Loonen
AJ
de Jager
CP
Tosserams
J
et al
Biomarkers and molecular analysis to improve bloodstream infection diagnostics in an emergency care unit
PLoS One
 
2014
9
e87315
169.
Opota
O
Jaton
K
Greub
G
Microbial diagnosis of bloodstream infection: towards molecular diagnosis directly from blood
Clin Microbiol Infect
 
2015
21
323
331
170.
Schreiber
J
Nierhaus
A
Braune
SA
et al
Comparison of three different commercial PCR assays for the detection of pathogens in critically ill sepsis patients
Med Klin Intensivmed Notfmed
 
2013
108
311
318
171.
Wellinghausen
N
Kochem
AJ
Disque
C
et al
Diagnosis of bacteremia in whole-blood samples by use of a commercial universal 16S rRNA gene-based PCR and sequence analysis
J Clin Microbiol
 
2009
47
2759
2765
172.
Pittet
D
Li
N
Woolson
RF
et al
Microbiological factors influencing the outcome of nosocomial bloodstream infections: a 6-year validated, population-based model
Clin Infect Dis
 
1997
24
1068
1078
173.
Miller
PJ
Wenzel
RP
Etiologic organisms as independent predictors of death and morbidity associated with bloodstream infections
J Infect Dis
 
1987
156
471
477
174.
Felton
T
Troke
PF
Hope
WW
Tissue penetration of antifungal agents
Clin Microbiol Rev
 
2014
27
68
88
175.
Pakyz
AL
Gurgle
HE
Oinonen
MJ
Antifungal use in hospitalized adults in U.S. academic health centers
Am J Health Syst Pharm
 
2011
68
415
418
176.
Kollef
M
Micek
S
Hampton
N
et al
Septic shock attributed to Candida infection: importance of empiric therapy and source control
Clin Infect Dis
 
2012
54
1739
1746
177.
Blot
SI
Vandewoude
KH
Hoste
EA
et al
Effects of nosocomial candidemia on outcomes of critically ill patients
Am J Med
 
2002
113
480
485
178.
Garrouste-Orgeas
M
Timsit
JF
Tafflet
M
et al
Excess risk of death from intensive care unit-acquired nosocomial bloodstream infections: a reappraisal
Clin Infect Dis
 
2006
42
1118
1126
179.
de With
K
Steib-Bauert
M
Knoth
H
et al
Hospital use of systemic antifungal drugs
BMC Clin Pharmacol
 
2005
5
: 1.
180.
Zarb
P
Amadeo
B
Muller
A
et al
Antifungal therapy in European hospitals: data from the ESAC point-prevalence surveys 2008 and 2009
Clin Microbiol Infect
  2012;
18
E389
395
181.
Dellinger
RP
Levy
MM
Rhodes
A
et al
Surviving sepsis campaign: international guidelines for management of severe sepsis and septic shock: 2012
Crit Care Med
 
2013
41
580
637
182.
Angus
DC
Linde-Zwirble
WT
Lidicker
J
et al
Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care
Crit Care Med
 
2001
29
1303
1310
183.
Ferrer
R
Martin-Loeches
I
Phillips
G
et al
Empiric antibiotic treatment reduces mortality in severe sepsis and septic shock from the first hour: results from a guideline-based performance improvement program
Crit Care Med
 
2014
42
1749
1755
184.
Investigators
TP
A randomized trial of protocol-based care for early septic shock
N Engl J Med
 
2014
370
1683
1693
185.
Allou
N
Allyn
J
Montravers
P
When and how to cover for fungal infections in patients with severe sepsis and septic shock
Curr Infect Dis Rep
 
2011
13
426
432
186.
Bassetti
M
Righi
E
Ansaldi
F
et al
A multicenter study of septic shock due to candidemia: outcomes and predictors of mortality
Intensive Care Med
 
2014
40
839
845
187.
Gutierrez
SM
Heredia
M
Gomez
E
et al
Candidemia in ICU patients with sepsis
Crit Care Med
 
2013
41
e385
188.
Guzman
JA
Tchokonte
R
Sobel
JD
Septic shock due to candidemia: outcomes and predictors of shock development
J Clin Med Res
 
2011
3
65
71
189.
Kollef
MH
Paiva
JA
Charles
PE
Candidemia and non-candidemia related septic shock: are there differences between them
?
Intensive Care Med
 
2014
40
1046
1048
190.
Patel
GP
Simon
D
Scheetz
M
et al
The effect of time to antifungal therapy on mortality in Candidemia associated septic shock
Am J Ther
 
2009
16
508
511
191.
Wisplinghoff
H
Seifert
H
Wenzel
RP
et al
Inflammatory response and clinical course of adult patients with nosocomial bloodstream infections caused by Candida spp
Clin Microbiol Infect
 
2006
12
170
177
192.
Guillamet
CV
Vazquez
R
Micek
ST
et al
Development and validation of a clinical prediction rule for candidemia in hospitalized patients with severe sepsis and septic shock
J Crit Care
 
2015
30
715
720
193.
Kumar
A
Roberts
D
Wood
KE
et al
Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock
Crit Care Med
 
2006
34
1589
1596
194.
Diekema
DJ
Pfaller
MA
Rapid detection of antibiotic-resistant organism carriage for infection prevention
Clin Infect Dis
 
2013
56
1614
1620
195.
Bilir
SP
Ferrufino
CP
Pfaller
MA
et al
The economic impact of rapid Candida species identification by T2Candida among high-risk patients
Future Microbiol
 
2015
10
1133
1144