185. Trends in Clinical Presentation and Antibiotic Resistance of Viridans Group Streptococci Bloodstream Infections in Immunocompromised Children

Abstract Background Levofloxacin prophylaxis (LVXp) is recommended in children with severe neutropenia from underlying malignancy or hematopoietic cell transplantation (HCT). The impact of LVXp on the epidemiology of viridans group streptococcus bloodstream infections (VGS-BSI) is unknown. At our center, LVXp was prescribed to high-risk children with expected prolonged neutropenia (ANC < 100, > 7 days) as part of a clinical trial (2013-17) and routinely since November 2018. We aim to describe our local epidemiology, antibiotic susceptibilities, and clinical outcomes of VGS-BSI over time. Methods VGS-BSI from 1/1/10-1/31/21 were identified via the laboratory database. Clinical data of patients followed at NCH with underlying malignancy, severe neutropenia, or HCT were extracted from the electronic health record. Available VGS isolates were subcultured, species identification confirmed by MALDI-ToF or 16s rDNA sequencing and susceptibility to penicillin (PCN), cefepime (CEF), vancomycin (VAN), and LVX performed via Etest per CLSI M100 guidelines. Non-parametric descriptive statistics were applied. Results Over a 10-yr period, 111 VGS-BSI occurred in 93 patients (Table 1); 15 (16%) patients had ≥ 2 VGS-BSI. 80 (86%) patients had fever and neutropenia (F&N); 26 (28%) required ICU care for vasopressors (N=17, 18%) or mechanical ventilation (N=10, 11%). Most VGS isolates were S. mitis/oralis group. In total, 15 (16%) patients received LVXp ≤ 6 months before VGS-BSI; 9 (10%) had breakthrough VGS-BSI while receiving LVXp and all isolates were LVX resistant. Figure 1 shows susceptibilities: overall, 24% of isolates had frank resistance to PCN, 19% CEF, 13% LVX; all were VAN susceptible. When evaluating for changes in susceptibilities over time, there was a significant difference in the proportion of LVX-resistant isolates (p=0.009, Cochran-Armitage χ 2), but not CEF (p=0.08) or PCN (p=0.86). Table 1. Demographic and Clinical Characteristics of Immunocompromised Children with Viridans Group Streptococci Bloodstream Infections (VGS-BSI) Figure 1. Antimicrobial Susceptibility Profile of Viridans Group Streptococci Bloodstream Isolates from Immunocompromised children, 2010-2021. Of 111 VGS-BSI reported during the study period from immunocompromised children, 83 (75%) were available for further testing. Antimicrobial susceptibility testing was performed by Etest and interpreted per CLSI M100. Susceptibility profiles to penicillin (PCN), cefepime (CEP) and, levofloxacin (LVX) are shown. Abbreviations: S—susceptible, I—intermediate, R—resistant. Conclusion Breakthrough, LVX-resistant VGS-BSI occurred in 10% of patients, most frequently in children with AML or HCT. Over time, there was a trend towards increased LVX resistance in the cohort. Routine antimicrobial testing and ongoing monitoring for emergence of resistance are warranted to inform local prophylaxis and empirical antibiotic strategies for high-risk children with F&N. Disclosures Monica I. Ardura, DO, MSCS, Shire (Grant/Research Support)

Background. In 2013, the Clinical and Laboratory Standards Institute recommended inducible clindamycin resistance (ICR) testing on macrolide-resistant Streptococcus pneumoniae isolates, which arises due to the ermB gene. Ribosomal methylation by ermB confers resistance to macrolides (high-level resistance), lincosamides and streptogramin B. The goal of our study is to characterize the prevalence of ICR among pediatric pneumococcal isolates.
Methods. We identified erythromycin-resistant(R) (minimum inhibitory concentration [MIC] ≥ 1 µg/mL) and clindamycin-susceptible(S) (MIC ≤ 0.25 µg/ mL) pneumococcal isolates from pediatric patients seen at Children's Mercy Hospital from 2007 to 2017. Determination of ICR was achieved via disk approximation (D-zone test) with standard erythromycin (15 µg) and clindamycin (2 µg) disks. Isolates with high-level erythromycin resistance (MIC ≥ 32µg/mL) were also tested for ermB gene by PCR. Positive and negative controls were used for D-zone test and ermB PCR.

Conclusion.
Erythromycin-R and clindamycin-S pneumococcal isolates did not express ICR and isolates with high-level erythromycin-R did not carry ermB. Multicenter studies are needed to determine if ICR testing is required for macrolide-resistant pneumococcal isolates in the PCV13 era. Background. Levofloxacin prophylaxis (LVXp) is recommended in children with severe neutropenia from underlying malignancy or hematopoietic cell transplantation (HCT). The impact of LVXp on the epidemiology of viridans group streptococcus bloodstream infections (VGS-BSI) is unknown. At our center, LVXp was prescribed to high-risk children with expected prolonged neutropenia (ANC < 100, > 7 days) as part of a clinical trial (2013-17) and routinely since November 2018. We aim to describe our local epidemiology, antibiotic susceptibilities, and clinical outcomes of VGS-BSI over time.
Methods. VGS-BSI from 1/1/10-1/31/21 were identified via the laboratory database. Clinical data of patients followed at NCH with underlying malignancy, severe neutropenia, or HCT were extracted from the electronic health record. Available VGS isolates were subcultured, species identification confirmed by MALDI-ToF or 16s rDNA sequencing and susceptibility to penicillin (PCN), cefepime (CEF), vancomycin (VAN), and LVX performed via Etest per CLSI M100 guidelines. Non-parametric descriptive statistics were applied.

Characteristics of COVID-19 Vaccine Breakthrough Cases in Minnesota, 2021
Stephanie Methods. COVID-19 VB cases were MN residents with completed COVID-19 vaccination series ≥14 days prior to symptom onset or positive for SARS-CoV-2 by nucleic acid amplification or antigen test. COVID-19 cases were reported to MDH and COVID-19 vaccinations reported to the MN Immunization Information Connection (MIIC). COVID-19 cases were matched to MIIC to identify VB and interviewed; medical records of hospitalized cases were reviewed. Available VB case specimens underwent whole genome sequencing (WGS) at MDH or collaborating lab.
Of 604 VB case specimens, 79% were B. Background. Households are important for SARS-CoV-2 transmission due to close proximity in enclosed living spaces over long durations. Using contact tracing, the secondary attack rate in households is estimated at 18-20%, yet no studies have examined COVID-19 clustering within households, an important measure to inform testing and prevention. We sought to quantify and characterize household clustering of COVID-19 cases in Fulton County, Georgia.
Methods. We used state surveillance data to identify all PCR-or antigen-confirmed cases of COVID-19 in Fulton County. Clustered cases were defined as cases with matching street address, including unit number. Communal places (e.g., nursing homes, correctional facilities) were excluded, as were apartments missing unit number. Household clusters were defined as ≥2 COVID-19 cases at the same residential address with positive sample collection dates within 14 days of one another. We described proportion of COVID-19 cases that were clustered, stratified by age, sex, and race/ethnicity over time.
Results. There were 60,614 COVID-19 cases with available address reported in Fulton County during 6/1/20-4/30/21. Of these, 25,149 (41.6%) had an address that matched at least one other case; 20,793 (34.3%) were from 8,582 household clusters with positive sample collection dates within 14 days (Fig 1). Majority of clusters had 2 individuals (N=6119, 71%), though some had ≥6 individuals (N=79, 0.9%). Clustering increased through January 2021 (Fig 2). Children were more likely to be in household clusters (Fig 4) and 15% of clusters had a child as first diagnosed case with increases since January 2021 (Fig 3). Consistently higher clustering was observed among Hispanic persons, with rising clustering among Asian persons (Fig 5).