Abstract

Since around 2000—earlier in Poland and Spain and later in France and the UK—dramatic shifts have occurred in the prevalence and types of extended-spectrum β-lactamases (ESBLs) in Europe. Before this watershed, most producers were nosocomial isolates, often Klebsiella spp. or Enterobacter spp. from specialist care units, and had mutant TEM or SHV ESBLs. Subsequently, CTX-M ESBLs have become dominant, with much greater penetration into Escherichia coli, and with many infections in ‘complicated community’ patients, usually with underlying disease, recent antibiotic usage, or healthcare contact. The degree of clonality among producers varies with the country, as does the enzyme type produced, with group 9 (CTX-M-9 and -14) enzymes dominant in Spain and group 1 enzymes (particularly CTX-M-3 and -15) dominant elsewhere. Irrespective of the particular enzyme, most producers are multiresistant. These changing patterns present major therapeutic and infection control challenges, with the public health intervention points unclear.

Introduction

Until the late 1990s, European surveys of extended-spectrum β-lactamases (ESBLs) almost exclusively found TEM and SHV enzyme variants, often SHV-2 and SHV-5, and largely found these in Klebsiella spp. Many ESBL-producing outbreak strains of Klebsiella pneumoniae were described, with a few ‘epidemic’ clones affecting multiple hospitals, notably serotype K25 lineages with SHV-4 enzyme that spread in Belgium and France,1,2 and also an Enterobacter aerogenes clone with TEM-24 enzyme that became (and remains) widespread in Belgium and France.3–6 Affected patients were mostly in specialist units, and European surveys in 1994 and 1997–98 found ESBLs in 23–25% of all Klebsiella spp. from ICUs.7,8 CTX-M ESBLs were recorded rarely, although there were large outbreaks of Salmonella Typhimurium with CTX-M-4 and -5 enzymes in Latvia,9 Russia and Belarus6 in the mid-1990s.

These patterns have now changed dramatically, with CTX-M enzymes replacing TEM and SHV mutants as the predominant ESBLs in many European countries, with Escherichia coli joining K. pneumoniae as a major host, and with producers increasingly isolated from community patients. CTX-M enzymes are supplanting TEM and SHV variants in East Asia too,10,11 just as one of them (CTX-M-2) did in the early 1990s in Argentina.12 Only in North America are TEM and SHV mutants still dominant, though substantial outbreaks of E. coli with CTX-M-15 β-lactamase have occurred in Canada13,14 and a scatter of ICAAC abstracts describe CTX-M producers in the USA.

This paper, written on behalf of the β-Lactamase Work Packages of the EU-funded COBRA (Combating Resistance to Antibiotics by Broadening the Knowledge on Molecular Mechanisms behind Resistance to Inhibitors of Cell Wall Synthesis) Consortium summarizes the current European situation by country. It does not aim to be a comprehensive account of the biochemistry, genetics or evolution of CTX-M β-lactamases; others have reviewed these topics recently and well.15,16 It should however be said that over 50 CTX-M β-lactamases are recognized and that they divide into five clusters on sequence homology, namely the CTX-M-1, -M-2, -M-8, -M-9 and -M-25 groups (). Group 1 and 2 types evolved by the escape of chromosomal genes from Kluyvera ascorbata,17 whereas group 8 and 9 enzymes evolved via similar escapes from Kluyvera georgiana.18 Once mobilized, blaCTX-M genes can be hosted by many elements, but most often by large multiresistance plasmids. ISEcp1 insertion sequence elements were often involved in the initial mobilization events13,19 but this is not universally true, particularly for group 2 and 9 enzymes,16,20 and analysis of a 12 kb region surrounding blaCTX-M-10 from different isolates revealed links to a phage-related element, which may have facilitated the initial escape of blaCTX-M-10 from Kluyvera spp. Expression is often from the promoter in ISEcp1, but may be from those in unusual class 1 integrons.21

CTX-M enzymes are more active against cefotaxime and ceftriaxone than ceftazidime, but point mutations can increase activity against ceftazidime; thus CTX-M-15 and -32 differ from CTX-M-3 and -1, respectively, solely by Asp-240→Gly substitutions, but are 100-fold more active against ceftazidime.22,23 Cephamycins, temocillin and carbapenems are not hydrolysed by CTX-M enzymes; clavulanate, tazobactam and sulbactam inhibit activity, but producers are often resistant to β-lactamase inhibitor combinations because of concurrent production of inhibitor-resistant penicillinase, (e.g. OXA-1), sometimes encoded by the same plasmids.13,24,25

CTX-M enzymes, by country

The United Kingdom

No isolates with CTX-M enzymes were reported in the UK before 2000, when a single Klebsiella oxytoca with CTX-M-9 was found.26 This was followed, in 2001, by a clonal outbreak in a Birmingham hospital, involving 30 patients and caused by a K. pneumoniae strain with CTX-M-26 β-lactamase.27 Also in 2001, a survey examined over 900 E. coli from 28 hospitals in the UK and Ireland and recorded four isolates with CTX-M-15 enzyme.28 These were unique by PFGE, were from three hospitals, and were a harbinger of what was to follow. Unnoticed strains with CTX-M enzymes were present earlier, as revealed by retrospective detection of CTX-M group 9 enzymes in Salmonella enterica serotype Virchow isolates from the 1990s, several of them from patients with a history of foreign travel.29

In mid-2003 the Health Protection Agency began to receive requests to investigate ‘outbreaks’ (in the loosest sense) of ESBL-producing E. coli from community as well as hospital patients. On receipt, over 90% of these isolates proved to have CTX-M-15 enzyme or, much more rarely, CTX-M-3 or -9.30 In the subsequent 24 months the Agency received over 1200 producers, from over half of all the clinical microbiology laboratories in the UK. These represent only a small fraction of all producers isolated. A prospective survey was undertaken late in 2004, covering 16 laboratories in south-east England, and seeking up to 100 consecutive cephalosporin-resistant Enterobacteriaceae per site. This yielded 1127 isolates with confirmed cephalosporin resistance.31 Among those with substantive mechanisms (ESBLs, AmpC or hyperproduced K1 enzyme), 51% were E. coli, and the largest group, comprising 292 isolates, were E. coli with CTX-M enzymes. CTX-M types also were the dominant ESBLs in Klebsiella spp. (Table 1). Just 4 years previously the dominant cephalosporin resistance types had been AmpC-derepressed Enterobacter spp. and Klebsiella spp. with TEM and SHV ESBLs, and only four E. coli with CTX-M enzymes were found.28,32

Table 1

Mechanisms found among consecutive cefpodoxime-, cefotaxime- or ceftazidime- resistant E. coli, Klebsiella spp. or Enterobacter spp. collected at 16 laboratories in London and south-east England from August to October 200431

 E. coli (n = 574) Klebsiella spp. (n = 224) Enterobacter spp. (n = 157) 
CTX-M ESBL 292 190 
Non-CTX-M ESBL 88 25 20 
AmpC—chromosomal or plasmid-mediated 41 72 
Hyperproduction of K1 chromosomal β-lactamase 
No substantive mechanism defined; low-level resistance, mostly to cefpodoxime only 153 59 
 E. coli (n = 574) Klebsiella spp. (n = 224) Enterobacter spp. (n = 157) 
CTX-M ESBL 292 190 
Non-CTX-M ESBL 88 25 20 
AmpC—chromosomal or plasmid-mediated 41 72 
Hyperproduction of K1 chromosomal β-lactamase 
No substantive mechanism defined; low-level resistance, mostly to cefpodoxime only 153 59 

UK E. coli isolates with CTX-M-15 β-lactamase include five major serotype O25 clones, designated A–E, along with a great diversity of non-clonal producers.30 The major clones had 78% similarity by PFGE and may share a common ancestor. The most prevalent of them, A, is less resistant to cephalosporins than the others, because of an IS26 element between blaCTX-M-15 and its normal promoter. It is dominant in several parts of the UK (Figure 1), whilst other areas have the more localized B–E clones, or predominantly have non-clonal producers. Around Preston (north-west England; light grey circle in Figure 1), some strain A E. coli additionally have a plasmidic AmpC β-lactamase, CMY-23.33 A minority (7%) of E. coli with CTX-M enzymes have group 9 (CTX-M-9 or -14) enzymes; these are non-clonal or form small local clusters.34 Less work has been done on Klebsiella spp. with CTX-M enzymes but, again, CTX-M-15 is dominant.31

Figure 1

Occurrence of the epidemic E. coli strain A with CTX-M-15 β-lactamase in the UK, 2003–5.

Figure 1

Occurrence of the epidemic E. coli strain A with CTX-M-15 β-lactamase in the UK, 2003–5.

Regardless of species or enzyme type, most producers are multiresistant to aminoglycosides (except gentamicin for E. coli strain A), classical tetracyclines, quinolones, trimethoprim and sulphonamides. β-Lactamase/inhibitor combinations have variable activity: most isolates with CTX-M-15 enzyme are resistant because of concurrent production of OXA-1 penicillinases, but sporadic isolates with group 9 enzymes mostly are susceptible.30 Drugs generally remaining active include carbapenems, nitrofurantoin, fosfomycin, temocillin and tigecycline. A few K. pneumoniae isolates with CTX-M-15 enzyme are carbapenem-resistant because of porin loss, with ertapenem more compromised than imipenem or meropenem.35 These are widely scattered, but nowhere frequent.

Most (77%) producers are from urinary infections,31 with minorities from bacteraemias or other sites. Many (45% in the 2004 survey31) are indicated as coming from community patients, but diligent enquiry often reveals that these individuals are elderly, have multiple underlying health problems (e.g. diabetes or dementia), and have been hospitalized in the preceding 1–3 years.

In Shropshire, which was an early epicentre of infections with E. coli strain A, there were 25 deaths among the first 108 cases, with infection deemed contributory to death in 10 of the first 54 deaths, and possibly contributory in a further four.24 Stool cultures detected ESBL producers, including strain A, in 4.5% and 2.5% of diarrhoeal in- and outpatients, respectively in Shropshire.24 Isolates with CTX-M enzymes were also found in 2% of diarrhoeal patients around York,36 although these mostly had group 9 enzymes, as did those from diarrhoeal calves in Wales,37 implying little link to the major clinical problem. There is no suggestion that the CTX-M+E. coli were related to the diarrhoea; diarrhoeal faeces were screened solely because of laboratory availability. Nevertheless, gut carriage is potentially significant since most urinary and intra-abdominal infections with E. coli arise endogenously.

France

French ESBL surveys during the 1990s showed that an E. aerogenes clone with TEM-24 β-lactamase and several K. pneumoniae clones with SHV-4 enzyme had become widespread.2–4,38,39 The E. aerogenes clone is also widespread in Belgium, and has been found in Italy, Spain and Portugal, with the earliest representatives dating from 1988.40

One of the first CTX-M enzymes described, CTX-M-1, was discovered in France in 1989.41 A decade later CTX-M-3 was found in an Enterobacter cloacae isolate recovered in the suburbs of Paris, from a patient without overseas travel.42 Shortly afterwards, Dutour et al.43 reported Enterobacteriaceae with CTX-M-1, -3 and -14 enzymes from several Parisian hospitals, and demonstrated that the encoding plasmids were related to elements identified a decade earlier. Retrospectively examining enterobacteria recovered between 1989 and 2000 in three Parisian hospitals, Saladin et al.44 identified nine E. coli and Proteus mirabilis that produced CTX-M-1, -2, -9, -14, -20 or -21 enzymes. Despite these early discoveries, producers of CTX-M enzymes remained rare during the 1990s. A survey in Aquitaine (south-west France) in 1999 found ESBLs in only 1.5% of Enterobacteriaceae from private laboratories serving community and healthcare centre patients;45 the TEM-24+ clone of E. aerogenes was widely represented, but only one CTX-M enzyme producer was identified, an E. coli isolate with CTX-M-1.

As elsewhere in Europe, CTX-M enzymes are accumulating with the new century, especially in the north of France. An E. coli strain with CTX-M-15 β-lactamase caused an outbreak from October 2001 to March 2003 in a 35-bed long-term care facility in a suburb of Paris,46 involving 26/47 residents. By 2002–2003 E. coli was the main host species for ESBLs at multiple hospitals in and around Paris, with many of the producers clonally related, at least within sites, and with CTX-M-15 the dominant type.47–50 Other CTX-M types (CTX-M-3, -10 and -14) continued to be seen, as did non-CTX-M types, predominantly TEM-3 and, in E. aerogenes, TEM-24. Many of the isolates belonged to phylo-group B2, which is associated with extra-intestinal infections; they were variably resistant to aminoglycosides and tetracyclines. By contrast to these studies in northern France, surveys in 2002–2003 in the Auvergne (south-east France)51 and southern France52 found that E. aerogenes remained the most frequent ESBL producer, with TEM-3 and TEM-24 accounting for 90% of all ESBLs. This north–south divide may now be breaking down, and a 2004 study identified CTX-M enzymes in southern France, including in hospitals at Perpignan, Toulouse and Montpellier53 whereas further work shows that CTX-M-15 is widespread around Reims in the east (C. De Champs and P. Nordmann, unpublished data).

Whilst most work has concentrated on producer strains from hospitals and long-term care facilities, the community spread of E. coli with CTX-M-15 enzyme is illustrated by two reports, one of a Salmonella Typhimurium strain with CTX-M-1 enzyme and the other of a Shigella sonnei strain with CTX-M-15;48 neither patient had travelled abroad. S. enterica Virchow with CTX-M-9 enzyme has been identified in France from poultry as well as humans.54

Spain and Portugal

Reports of ESBL-producing Enterobacteriaceae in Spain date from 198855 and, as in other European countries, early publications concerned blaSHV or blaTEM variants.55–57 CTX-M β-lactamases were first reported in 2000, with the publication of papers describing E. coli and Salmonella with CTX-M-9 recovered in Barcelona and Murcia in 1996–9858,59 and an E. coli isolate with CTX-M-10 enzyme recovered in Madrid in 1997.60 Subsequent re-examination of ESBL-producing K. pneumoniae and Enterobacter collected in Madrid from 1988 onwards revealed that CTX-M enzymes had emerged in Spain at least by the early 1990s,5,61 only a few years after their first discovery in Germany, Japan and Argentina. The earliest producers found were K. pneumoniae from 1990—one with CTX-M-10 enzyme from an outpatient urine sample,61 the other, with CTX-M-9, from a gastroenterology inpatient; also an Enterobacter gergoviae with CTX-M-10 was recovered from a catheter urine in 1991.5 CTX-M-10 β-lactamase was also found in clinical E. coli isolates and in faecal Citrobacter freundii and K. pneumoniae isolates from outpatients from 1991.62,63

Despite these early examples, CTX-M β-lactamases did not become prevalent in Spain in the 1990s. A study in Barcelona between 1994 and 1996 found that only 7% of E. coli isolates with decreased susceptibilities to broad-spectrum cephalosporins had CTX-M-9-like enzymes64 and a long-term (1995–2003) surveillance of K. pneumoniae and E. coli in Seville first recorded CTX-M producers only from 1998.65 As in other European countries, this pattern has since changed dramatically, with multiple reports of CTX-M β-lactamase-producing isolates, most of them from community patients.62,65–70 One multicentre study examined all E. coli and K. pneumoniae isolates with an ESBL phenotype from March to June 2000 from 40 hospitals across Spain.67,68 ESBLs were found in 0.5% and 2.7% of E. coli and K. pneumoniae, respectively and it was notable that 90% of participating centres recovered producers. The most prevalent ESBLs in E. coli were CTX-M-9 (27.3%), SHV-12 (23.9%) and CTX-M-14 (16.7%). CTX-M-10 enzyme, though longer established, was present in only 4.5% of producer isolates. In the case of K. pneumoniae, CTX-M-10 (12.5%) was the only CTX-M enzyme type found, whilst TEM-4 (25%) and TEM-3 (16.7%) were the most common ESBLs. E. coli isolates with CTX-M-9 and -14 enzymes were encountered widely, whereas CTX-M-10 was concentrated in the central region, with just a few producers from the north.68,71 Fifty-one per cent of E. coli with ESBLs (but only 7% of the K. pneumoniae) were from non-hospitalized patients. There was little clonality among isolates with CTX-M enzymes,71 although a few strains broke this pattern, as in the case of an E. coli lineage with a unique CTX-M-9-encoding plasmid, observed in faecal samples of multiple attendees at a summer camp in 2002.72

The high prevalence of CTX-M-9 enzyme found in these large-scale surveys is corroborated by local studies of clinical and faecal E. coli, K. pneumoniae and Salmonella spp. isolates73 from hospitalized and community patients, and from healthy and sick chickens.74 CTX-M-14 enzyme, which also belongs to CTX-M group 9, also occurs widely,67 including from Salmonella spp.75 and in faecal E. coli from healthy volunteers with little or no hospital contact;75 it was the most frequent ESBL in a long-term study from Seville.65 Most recently, group 1 enzymes, including CTX-M-1, -3, -15, -28 and -32 have been encountered.23,70,74,76 As in the UK, Italy and France, CTX-M-15 seems to be spreading rapidly76 with producers also reported from Portugal;25 once again it is genetically linked with blaOXA-1. CTX-M-1 and -32 enzymes were also recovered from healthy and sick animals in 2003.74 Group 2 enzymes, which are widely distributed in South America and Israel, have recently been detected in clinical E. coli isolates from Barcelona76 and in a faecal E. coli isolate from a healthy volunteer in Madrid;62 enzymes belonging to the CTX-M-8 and -25 groups have not yet been found in Spain.

Among hospitalized patients, prior oxyimino-β-lactam use, diabetes, and underlying diseases were independent risk factors for infection or colonization with non-clonal E. coli that had CTX-M enzymes, whereas previous fluoroquinolone use was associated with infection or colonization with those with SHV and TEM enzymes.77 Among non-hospitalized patients, most ESBL-positive E. coli isolates (64%) had blaCTX-M-9 and were from patients with high scores for Charlson's co-morbidity index for severity of underlying disease.66 Many were old and reported fluoroquinolone use in the preceding 2 months. Most infections were of the urinary tract and almost half of the cases appeared truly community-acquired, as the patients lacked recent hospitalization and were not in nursing homes. Similar risk factors were reported for infections with ESBL producers outside the hospital in Israel, where CTX-M-2 predominates, although more patients had recent hospitalization.78

Dissemination of blaCTX-M-9 is associated with a few large conjugative plasmids of long-established incompatibility groups; the gene is located within class 1 integrons with a low, but increasing, diversity of resistance cassettes79,80 often also conferring resistance to trimethoprim and aminoglycosides. Fluoroquinolone resistance is common among isolates with CTX-M-9 and -14, but is not associated with qnr (P. Nordmann and L. Poirel, unpublished data). Dissemination of epidemic plasmids carrying blaCTX-M-14 or blaCTX-M-32 among E. coli has been described,73 as was transmission of a plasmid coding for CTX-M-10 between E. cloacae and various E. coli and K. pneumoniae strains.5,61,81

Italy

CTX-M-type enzymes were not sought in the first nationwide Italian survey of ESBL production, carried out in 1999.82 However, only 8% of collected Enterobacteriaceae isolates with ESBL phenotypes lacked TEM- and/or SHV-ESBLs, implying that any diffusion of CTX-M-type enzymes was limited.

Reports of Italian isolates with CTX-M ESBLs only began to appear in 2003, and then included: (i) several E. coli, E. aerogenes and C. freundii isolates with CTX-M-1 enzyme, but with no information on sources or clonal relationships;83 (ii) a few isolates with CTX-M enzymes (one K. pneumoniae with CTX-M-15; two related Proteus vulgaris isolates with CTX-M-2, and three unrelated E. coli isolates with CTX-M-1) from a hospital in northern Italy.84 In 2001–2002, only 2.6% of all ESBL producers had CTX-M phenotypes, with cefotaxime MIC > ceftazidime MIC.84

A second nationwide ESBL survey, in 2003, sought CTX-M enzymes specifically, and found them to be widespread85 Producers—mostly E. coli and, in lower numbers, K. pneumoniae—were detected in 10/11 participating centres and accounted for ∼20% of all ESBL-producing isolates, though this proportion varied from <2% to ∼50%. All the CTX-M enzymes were of group 1, with CTX-M-1 and -15 predominant and CTX-M-32 rarer. Producers were detected from inpatients and outpatients at similar rates. Genotyping revealed multiple lineages of E. coli and K. pneumoniae irrespective of whether the enzyme present was CTX-M-1 or -15. This diversity, and the ability to transfer ESBL determinants conjugatively, was greater among E. coli isolates with CTX-M-1 enzyme than among those with CTX-M-15.86

The rapid and recent dissemination of CTX-M-β-lactamase-producing E. coli was further documented by a longitudinal surveillance examining 20 000 isolates collected over 5 years in northern Italy.87 The prevalence of ESBLs increased steadily from 0.2% in 1999 to 1.6% in 2003, with this change largely attributable to CTX-M-β-lactamase-positive isolates, which comprised 38% of all ESBL producers in 2003 compared with 12% in 1999. Most had CTX-M-1 enzyme, which was also found in Citrobacter amalonaticus and Morganella morganii—unusual hosts for ESBLs. In both instances the isolates were from patients co-infected with CTX-M-1+E. coli, suggesting in vivo transfer.88

CTX-M-1 β-lactamase was present in 76% of ESBL-positive E. coli isolates from sick and healthy companion or stray dogs and cats, based on a survey carried out in Rome from 2001 to 2003. Perhaps even more strikingly this study found ESBL producers in specimens (mostly faeces) from 21 of the 298 animals examined.89

Poland

It is impossible to determine when CTX-M β-lactamase producers first appeared in Poland and whether they first emerged in nosocomial pathogens or in the community because, until the mid-1990s, Polish laboratories did not screen for ESBLs and there were no epidemiological surveys of ESBLs. ESBL surveys only commenced in 1996, when the then Sera and Vaccines Central Research Laboratory also began to promulgate the value and methodology of ESBL detection to clinical laboratories.

Among the first ESBL producers detected and analysed there were four clonal C. freundii isolates and one E. coli isolate from the Praski Hospital in Warsaw, one of the first centres to introduce routine ESBL detection.90 A then novel CTX-M variant, CTX-M-3, was identified in these isolates, and proved similar to CTX-M-1, previously observed in Germany and France.91,92,blaCTX-M-3 was located on a readily conjugative plasmid. Subsequent examination, from November 1996 to February 1997, found that CTX-M-3 was the predominant ESBL in the Praski Hospital,93 with producers recovered in many wards. Their prevalence reflected clonal spread of K. pneumoniae, C. freundii and Serratia marcescens producers, along with intense plasmid dissemination. The same blaCTX-M-3-encoding plasmid, originally identified in the C. freundii isolates from July 1996 proved widespread, and was designated plasmid A1, later pCTX-M3.90 Almost all the other encoding plasmids found were its derivatives. Hosts of pCTX-M3 family plasmids included 16 RAPD types of seven enterobacterial species (E. coli, K. pneumoniae, K. oxytoca, C. freundii, E. cloacae, S. marcescens and M. morganii). Several of the E. coli and K. pneumoniae isolates were from outpatients, though they may have had earlier hospitalization.

The first multicentre survey on ESBLs among Enterobacteriaceae in Polish hospitals was conducted in Spring 1998 and covered seven institutions (M. Gniadkowski, A. Barnaiak, J. Fiett and W. Hryniewicz, unpublished data). Isolates with CTX-M enzymes were found at six centres, and accounted for 19% of all ESBL producers collected. This frequency was below that of SHV ESBLs (60.4%, mainly SHV-5), but comparable to that of TEM ESBLs (20.8%). All the survey isolates with CTX-M enzymes, together with those from 11 other hospitals up to the end of 2000 (89 isolates altogether), were subjected to detailed analysis.94–96 Eighty-six had CTX-M-3 β-lactamase whereas three had its variant, CTX-M-15. In the vast majority of cases these enzymes were coded by conjugative plasmids of the pCTX-M3 family.97,98 A more recent (2003) survey covering 13 regional Polish hospitals further underscored the rise of CTX-M enzymes, which were found in 82% of all 264 ESBL-producing isolates (M. Gniadkowski, J. Empel, A. Barnaiak, J. Fiett, E. Literacka, A. Mrówka and W. Hryniewicz, unpublished data). Once again, the enzymes found were mostly CTX-M-3 or, less often, CTX-M-15 types and producers were strongly represented at all the participating centres, varying from 62.5% to 100% of all ESBL producers. CTX-M enzymes were found in even more species than previously, including E. aerogenes, P. mirabilis and Providencia rettgeri.

pCTX-M3 is an IncL/M, conjugative, broad-host-range plasmid (I. Kern-Zdanowicz, M. Golębiewski, M. Zienkiewicz, M. Adamczyk, M. Gniadkowski and P. Ceglowski, unpublished data) with a molecular mass of 89 468 bp (GenBank accession number AF550415). Apart from blaCTX-M-3, it carries blaTEM-1, dfr (dihydrofolate reductase), aac(3)-II and aadA2 (aminoglycoside-modifying enzyme) genes; dfr and aadA2 lie within a class 1 integron, which may be part of a composite transposon formed by two IS26 elements. blaCTX-M-3 is accompanied by an ISEcp1 element, 128 bp upstream from the coding region (ref. 96 and M. Gniadkowski and A. Baraniak, unpublished data), which seems likely to have been involved in the initial mobilization.19 Recently, a 1377 bp fragment of pCTX-M3, starting just behind ISEcp1 and encompassing blaCTX-M-3 along with most of orf477, was found to be very similar to a chromosomal DNA fragment from a K. ascorbata strain,17 suggesting a possible origin. blaCTX-M-15 genes from Polish isolates were similarly spaced from ISEcp1 as for blaCTX-M-3 and had the same flanking sequences;96 moreover, they are located in pCTX-M3-type plasmids, implying that they had emerged by point mutation of blaCTX-M-3, not via separate gene escapes.

In summary, the ESBL epidemiology in Poland is dominated by CTX-M producers, which have occurred for at least 10 years and are now widespread in hospitals and among bacterial species. The pool of blaCTX-M variants is very homogeneous, with blaCTX-M-3 dominant and, although a few isolates have blaCTX-M-15, these probably are direct descendants of those with blaCTX-M-3. Almost all the blaCTX-M-3 genes seem to have arisen from a single mobilization event, with subsequent intense dissemination of plasmid pCTX-M3 and its derivatives. Recent unpublished data suggest spread in the community, though studies are limited.

Elsewhere in Europe

This article has concentrated on France, Italy, Poland, Spain and the UK, but the rise of CTX-M enzymes has occurred more widely. National spread of a K. pneumoniae clone with CTX-M-15 has recently been reported in Hungary99 whilst there is good evidence that E. coli and K. pneumoniae with CTX-M enzymes are becoming widely scattered, if not frequent, in many other European countries (Figure 2).25,99–105 It is notable that E. coli with these enzymes are causing concern even in Scandinavian countries with an exemplary record for infection control.106 CTX-M-15 is the most-reported CTX-M type across most of the further countries for which data are available, with CTX-M-1 and -3 also widely reported (Figure 2). Exceptionally, one Belgian study found that CTX-M-2 accounted for 14% of all CTX-M types.104

Figure 2

Dominant and frequent CTX-M β-lactamase types in different European countries. Data for France, Italy, Poland, Spain and the UK are based on the references cited in the text. Those for other countries are based on further reports, 25,99–105 also, for Croatia, B. Bedenic and M. Gniadkowski., unpublished data and, for Switzerland, A. Wenger and P. Nordmann, unpublished data, with national dominance only inferred based on large-scale surveys. Many other CTX-M enzymes have been isolated on a few occasions or (as with CTX-M-5-producing Salmonella Typhimurium in Latvia) have caused sizeable but time-defined outbreaks before apparently declining. CTX-M-type enzymes are emerging rapidly also in Greece but reports that stress prevalence do not identify the particular enzyme types.

Figure 2

Dominant and frequent CTX-M β-lactamase types in different European countries. Data for France, Italy, Poland, Spain and the UK are based on the references cited in the text. Those for other countries are based on further reports, 25,99–105 also, for Croatia, B. Bedenic and M. Gniadkowski., unpublished data and, for Switzerland, A. Wenger and P. Nordmann, unpublished data, with national dominance only inferred based on large-scale surveys. Many other CTX-M enzymes have been isolated on a few occasions or (as with CTX-M-5-producing Salmonella Typhimurium in Latvia) have caused sizeable but time-defined outbreaks before apparently declining. CTX-M-type enzymes are emerging rapidly also in Greece but reports that stress prevalence do not identify the particular enzyme types.

The best continent-wide resistance surveillance () does not distinguish ESBL producers from those with other modes of cephalosporin resistance, and has limited data for Enterobacteriaceae other than E. coli. Nevertheless, it shows widespread rises in cephalosporin resistance in E. coli from 2001 to 2005 (Figure 3); along with even more dramatic increases in fluoroquinolone resistance (see website).

Figure 3

Prevalence of resistance to extended-spectrum cephalosporins among E. coli isolates from bacteraemias, as reported under the European Antimicrobial Resistance Surveillance System () in 2001 and 2004, supplemented with UK data based on laboratories' reports to the Health Protection Agency.

Figure 3

Prevalence of resistance to extended-spectrum cephalosporins among E. coli isolates from bacteraemias, as reported under the European Antimicrobial Resistance Surveillance System () in 2001 and 2004, supplemented with UK data based on laboratories' reports to the Health Protection Agency.

Routes of spread

Relationships among strains with CTX-M enzymes from different countries remain largely unclear although, prima facie, it is likely that the continent-wide rise of CTX-M ESBLs reflects a series of independent events.

It seems that the pCTX-M3-type plasmids, encoding CTX-M-3, began to spread in Poland a little before related enzymes, predominantly CTX-M-15, became prevalent in western Europe. It therefore is reasonable to ask, whether increased movement between east and west Europe has allowed this ‘Polish’ plasmid to spread westwards. Some insight here can be gained by examining the length of the spacer region between ISEcp1 and blaCTX-M-3/15. On this basis it seems most likely that blaCTX-M-15 genes in isolates from the UK (E. Karisik, D.M. Livermore and N. Woodford, unpublished data), Boulogne49 and Lisbon107—also New Delhi,108 Istanbul,109 Toronto13 and Yaounde (Cameroon)110—emerged independently from those observed in Poland, since the ISEcp1 elements are located much closer (48 bp) to blaCTX-M. On the other hand, the ISEcp1-associated blaCTX-M-3 gene from an E. cloacae from Versailles (France) was located on a pCTX-M3-type plasmid.43 Similarity was also suggested between CTX-M-3 producers from Poland and Taiwan.111 A representative of the UK E. coli strain A was found in Austria, but without any obvious epidemiological link to the UK.103

It is plausible too that the E. coli clones with CTX-M-15 enzyme, now spreading in the UK and France, originated in other countries with which Europe has extensive and growing population exchanges, perhaps in India, where CTX-M-15 was first described,22 or North Africa.112 Clonal relationships have recently been noted between E. coli with CTX-M-15 enzymes from Paris, Tunis and, to a lesser extent, the Central African Republic.113 Such data do not, however, prove the direction of spread and, in the UK, the early spread of CTX-M-15 was not centred in conurbations with large immigrant populations.30 Moreover—if migration is proposed as a route of spread—it remains unclear why group 9 enzymes (mainly CTX-M-9 itself) currently predominate in Spain whereas the rest of Europe largely has group 1 (CTX-M-3 and -15) types (Figure 3). Group 9 types (CTX-M-9 or -14) are otherwise dominant in East Asia, notably China, whereas South America—with substantial population flows to and from Spain—predominantly has CTX-M-2 type enzymes, at least in its Southern ‘cone’. Within Eurasia, CTX-M-2 appears frequent only in Israel114 a country with fewer obvious cultural and migrational links than Spain to South America.

Food is another possible vector of spread and this article has repeatedly noted the detection of E. coli with CTX-M enzyme in food animals. Nevertheless, there is no proven link between this carriage and human infections. In the UK, at least, the enzyme types found in both food animals and in foodstuff belong to groups 2 and 9 (as in Spain74) whereas the huge majority of clinical producers have CTX-M-15.

Routes of transmission of Klebsiella spp. with ESBLs are well understood in the context of nosocomial outbreaks and whilst nosocomial transmission of E. coli clones is less common it can occur. What is less clear is the route by which community infections arise. On one hand, many patients with ‘community’ infections with CTX-M-β-lactamase-producing E. coli have a history of recent hospitalization,78 where they may have been colonized. In support of this view the distribution of enzyme producers among urinary infections is biased towards complex cases and older age groups,66 whereas a more random distribution, with more producers from uncomplicated cystitis, would be predicted if most acquisition was via the food chain in the community. On the other hand, not all colonized individuals have a history of hospitalization and it may be that low-level gut colonization occurs in the community, via the food chain, perhaps with plasmid transfer to resident E. coli, and that the proportion of resistant E. coli with CTX-M enzymes tends to be enriched during healthcare contacts, owing to frequent antimicrobial exposure. Screening populations for faecal or rectal carriage would be the obvious way to resolve these issues, but has not yet been undertaken on any wide scale.

Whatever the precise mode of spread (and spread through plasmid dissemination, hospital cross infection, down the food chain, and via human migration are not mutually exclusive), it is clear that Europe is moving to a situation where ESBLs are more common and less confined to hospitals, as well as one where E. coli is a major host species. If so, the opportunities for control are disturbingly small. Old data show that ampicillin resistance, largely due to TEM-1 enzyme, rose first in E. coli from hospital-acquired infections and only later among those from community-acquired cases.115 History may be repeating itself with CTX-M ESBLs.

Transparency declarations

Conflicts of interest: D. M. L., grants from AstraZeneca, Merck and Wyeth; speakers' bureaux for AstraZeneca, Johnson & Johnson, Merck and Wyeth; shareholdings in AstraZeneca GlaxoSmithkline, Pfizer and Schering Plough. G. M. R., grants from Wyeth; consultancies from Wyeth, Janssen-Cilag and Nabi Pharmaceuticals; speakers' bureaux for Wyeth and Merck; R. C., grants from Sanofi-Aventis and Wyeth. Other authors: no conflicts to declare.

The work of all co-authors on emerging β-lactamase problems is supported, in part, by the EU/FP6-funded COBRA project (6-PCRD LSHM-CT-2003-503-335). We are grateful to EARSS for permission to include Figure 3.

References

1
Arlet
G
Rouveau
M
Casin
I
, et al.  . 
Molecular epidemiology of Klebsiella pneumoniae strains that produce SHV-4 β-lactamase and which were isolated in 14 French hospitals
J Clin Microbiol
 , 
1994
, vol. 
32
 (pg. 
2553
-
8
)
2
Yuan
M
Aucken
H
Hall
LM
, et al.  . 
Epidemiological typing of klebsiellae with extended-spectrum β-lactamases from European intensive care units
J Antimicrob Chemother
 , 
1998
, vol. 
41
 (pg. 
527
-
39
)
3
Perilli
M
Dell'Amico
E
Segatore
B
, et al.  . 
Molecular characterization of extended-spectrum β-lactamases produced by nosocomial isolates of Enterobacteriaceae from an Italian nationwide survey
J Clin Microbiol
 , 
2002
, vol. 
40
 (pg. 
611
-
4
)
4
De Gheldre
Y
Struelens
MJ
Glupczynski
Y
, et al.  . 
National epidemiologic surveys of Enterobacter aerogenes in Belgian hospitals from 1996 to 1998
J Clin Microbiol
 , 
2001
, vol. 
39
 (pg. 
889
-
96
)
5
Canton
R
Oliver
A
Coque
TM
, et al.  . 
Epidemiology of extended-spectrum β-lactamase-producing Enterobacter isolates in a Spanish hospital during a 12-year period
J Clin Microbiol
 , 
2002
, vol. 
40
 (pg. 
1237
-
43
)
6
Machado
E
Coque
TM
Sousa
JC
, et al.  . 
Extended-spectrum β-lactamases (ESBLs) in Enterobacteriaceae from Portugal
2005
Abstracts of the Forty-fifth Interscience Conference on Antimicrobial Agents and Chemotherapy
Washington, DC
DC, USA
American Society for Microbiology Washington
pg. 
116
  
Abstract C2-774
7
Livermore
DM
Yuan
M
Antibiotic resistance and production of extended-spectrum β-lactamases amongst Klebsiella spp. from intensive care units in Europe
J Antimicrob Chemother
 , 
1996
, vol. 
38
 (pg. 
409
-
24
)
8
Babini
GS
Livermore
DM
Antimicrobial resistance amongst Klebsiella spp. collected from intensive care units in Southern and Western Europe in 1997–1998
J Antimicrob Chemother
 , 
2000
, vol. 
45
 (pg. 
183
-
9
)
9
Bradford
PA
Yang
Y
Sahm
D
, et al.  . 
CTX-M-5, a novel cefotaxime-hydrolyzing β-lactamase from an outbreak of Salmonella typhimurium in Latvia
Antimicrob Agents Chemother
 , 
1998
, vol. 
42
 (pg. 
1980
-
4
)
10
Munday
CJ
Xiong
J
Li
C
, et al.  . 
Dissemination of CTX-M type β-lactamases in Enterobacteriaceae isolates in the People's Republic of China
Int J Antimicrob Agents
 , 
2004
, vol. 
23
 (pg. 
175
-
80
)
11
Ling
TK
Xiong
J
Yu
Y
, et al.  . 
Multicenter antimicrobial susceptibility survey of gram-negative bacteria isolated from patients with community-acquired infections in the People's Republic of China
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
374
-
8
)
12
Radice
M
Power
P
Di Conza
J
, et al.  . 
Early dissemination of CTX-M-derived enzymes in South America
Antimicrob Agents Chemother
 , 
2002
, vol. 
46
 (pg. 
602
-
4
)
13
Boyd
DA
Tyler
S
Christianson
S
, et al.  . 
Complete nucleotide sequence of a 92-kilobase plasmid harboring the CTX-M-15 extended-spectrum β-lactamase involved in an outbreak in long-term-care facilities in Toronto, Canada
Antimicrob Agents Chemother
 , 
2004
, vol. 
48
 (pg. 
3758
-
64
)
14
Pitout
JD
Gregson
DB
Church
DL
, et al.  . 
Community-wide outbreaks of clonally related CTX-M-14 β-lactamase-producing Escherichia coli strains in the Calgary Health Region
J Clin Microbiol
 , 
2005
, vol. 
43
 (pg. 
2844
-
9
)
15
Walther-Rasmussen
J
Høiby
N
Cefotaximases (CTX-M-ases), an expanding family of extended-spectrum β-lactamases
Can J Microbiol
 , 
2004
, vol. 
50
 (pg. 
137
-
65
)
16
Bonnet
R
Growing group of extended-spectrum β-lactamases: the CTX-M enzymes
Antimicrob Agents Chemother
 , 
2004
, vol. 
48
 (pg. 
1
-
14
)
17
Rodriguez
MM
Power
P
Radice
M
, et al.  . 
Chromosome-encoded CTX-M-3 from Kluyvera ascorbata: a possible origin of plasmid-borne CTX-M-1-derived cefotaximases
Antimicrob Agents Chemother
 , 
2004
, vol. 
48
 (pg. 
4895
-
7
)
18
Olson
AB
Silverman
M
Boyd
DA
, et al.  . 
Identification of a progenitor of the CTX-M-9 group of extended-spectrum β-lactamases from Kluyvera georgiana isolated in Guyana
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
2112
-
5
)
19
Poirel
L
Decousser
JW
Nordmann
P
Insertion sequence ISEcp1B is involved in expression and mobilization of a blaCTX-M β-lactamase gene
Antimicrob Agents Chemother
 , 
2003
, vol. 
47
 (pg. 
2938
-
45
)
20
Valverde
A
Canton
R
Galan
JC
, et al.  . 
In117, an unusual In0-like class 1 integron containing CR1 and blaCTX-M-2 and associated with a Tn21-like element
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
799
-
802
)
21
Di Conza
JA
Gutkind
GO
Mollerach
ME
, et al.  . 
Transcriptional analysis of the blaCTX-M-2 gene in Salmonella enterica serovar Infantis
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
3014
-
7
)
22
Poirel
L
Gniadkowski
M
Nordmann
P
Biochemical analysis of the ceftazidime-hydrolysing extended-spectrum β-lactamase CTX-M-15 and of its structurally related β-lactamase CTX-M-3
J Antimicrob Chemother
 , 
2002
, vol. 
50
 (pg. 
1031
-
4
)
23
Cartelle
M
del Mar
TM
Molina
F
, et al.  . 
High-level resistance to ceftazidime conferred by a novel enzyme, CTX-M-32, derived from CTX-M-1 through a single Asp240-Gly substitution
Antimicrob Agents Chemother
 , 
2004
, vol. 
48
 (pg. 
2308
-
13
)
24
Livermore
DM
Hawkey
PM
CTX-M: changing the face of ESBLs in the UK
J Antimicrob Chemother
 , 
2005
, vol. 
56
 (pg. 
451
-
4
)
25
Mendonca
N
Louro
D
Castro
AP
, et al.  . 
CTX-M-15, OXA-30 and TEM-1-producing Escherichia coli in two Portuguese regions
J Antimicrob Chemother
 , 
2006
, vol. 
57
 (pg. 
1014
-
6
)
26
Alobwede
I
M'Zali
FH
Livermore
DM
, et al.  . 
CTX-M extended-spectrum β-lactamase arrives in the UK
J Antimicrob Chemother
 , 
2003
, vol. 
51
 (pg. 
470
-
1
)
27
Brenwald
NP
Jevons
G
Andrews
JM
, et al.  . 
An outbreak of a CTX-M-type β-lactamase-producing Klebsiella pneumoniae: the importance of using cefpodoxime to detect extended-spectrum β-lactamases
J Antimicrob Chemother
 , 
2003
, vol. 
51
 (pg. 
195
-
6
)
28
Mushtaq
S
Woodford
N
Potz
N
, et al.  . 
Detection of CTX-M-15 extended-spectrum β-lactamase in the United Kingdom
J Antimicrob Chemother
 , 
2003
, vol. 
52
 (pg. 
528
-
9
)
29
Hopkins
KL
Batchelor
MJ
Liebana
E
, et al.  . 
Characterisation of CTX-M and AmpC genes in human isolates of Escherichia coli identified between 1995 and 2003 in England and Wales
Int J Antimicrob Agents
 , 
2006
, vol. 
28
 (pg. 
180
-
92
)
30
Woodford
N
Ward
ME
Kaufmann
ME
, et al.  . 
Community and hospital spread of Escherichia coli producing CTX-M extended-spectrum β-lactamases in the UK
J Antimicrob Chemother
 , 
2004
, vol. 
54
 (pg. 
735
-
43
)
31
Potz
NA
Hope
R
Warner
M
, et al.  . 
Prevalence and mechanisms of cephalosporin resistance in Enterobacteriaceae in London and South-East England
J Antimicrob Chemother
 , 
2006
, vol. 
58
 (pg. 
320
-
6
)
32
Livermore
DM
Mushtaq
S
James
D
, et al.  . 
In-vitro activity of piperacillin/tazobactam and other broad-spectrum antibiotics against bacteria from hospitalised patients in the British Isles
Int J Antimicrob Agents
 , 
2003
, vol. 
22
 (pg. 
14
-
27
)
33
Woodford
N
Reddy
S
Fagan
E
, et al.  . 
Wide geographic spread of diverse acquired AmpC β-lactamases among Escherichia coli and Klebsiella spp. in the UK and Ireland
J Antimicrob Chemother
 , 
2006
 
doi:10.1093/jac/dkl456
34
Fagan
EJ
Warner
M
Pike
R
, et al.  . 
Characterisation of Escherichia coli producing CTX-M-9-like β-lactamase in the UK
Clin Microbiol Infect
 , 
2005
, vol. 
11
 
Suppl 2
pg. 
119
  
Abstract P464
35
Ward
ME
Woodford
N
Warner
M
, et al.  . 
Carbapenem-resistant, CTX-M producing Klebsiella pneumoniae in the UK
Clin Microbiol Infect
 , 
2005
, vol. 
11
 
Suppl 2
pg. 
403
  
Abstract P1266
36
Munday
CJ
Whitehead
GM
Todd
NJ
, et al.  . 
Predominance and genetic diversity of community and hospital acquired CTX-M extended-spectrum β-lactamases in York, UK
J Antimicrob Chemother
 , 
2004
, vol. 
54
 (pg. 
628
-
33
)
37
Teale
CJ
Barker
L
Foster
AP
, et al.  . 
Extended-spectrum β-lactamase detected in E. coli recovered from calves in Wales
Vet Rec
 , 
2005
, vol. 
156
 (pg. 
186
-
7
)
38
Arlet
G
Rouveau
M
Casin
I
, et al.  . 
Molecular epidemiology of Klebsiella pneumoniae strains that produce SHV-4 β-lactamase and which were isolated in 14 French hospitals
J Clin Microbiol
 , 
1994
, vol. 
32
 (pg. 
2553
-
8
)
39
Mammeri
H
Laurans
G
Eveillard
M
, et al.  . 
Coexistence of SHV-4- and TEM-24-producing Enterobacter aerogenes strains before a large outbreak of TEM-24-producing strains in a French hospital
J Clin Microbiol
 , 
2001
, vol. 
39
 (pg. 
2184
-
90
)
40
Marchandin
H
Carriere
C
Sirot
D
, et al.  . 
TEM-24 produced by four different species of Enterobacteriaceae, including Providencia rettgeri, in a single patient
Antimicrob Agents Chemother
 , 
1999
, vol. 
43
 (pg. 
2069
-
73
)
41
Bernard
H
Tancrede
C
Livrelli
V
, et al.  . 
A novel plasmid-mediated extended-spectrum β-lactamase not derived from TEM- or SHV-type enzymes
J Antimicrob Chemother
 , 
1992
, vol. 
29
 (pg. 
590
-
2
)
42
Doucet-Populaire
F
Ghnassia
JC
Bonnet
R
, et al.  . 
First isolation of a CTX-M-3-producing Enterobacter cloacae in France
Antimicrob Agents Chemother
 , 
2000
, vol. 
44
 (pg. 
3239
-
40
)
43
Dutour
C
Bonnet
R
Marchandin
H
, et al.  . 
CTX-M-1, CTX-M-3, and CTX-M-14 β-lactamases from Enterobacteriaceae isolated in France
Antimicrob Agents Chemother
 , 
2002
, vol. 
46
 (pg. 
534
-
7
)
44
Saladin
M
Cao
VT
Lambert
T
, et al.  . 
Diversity of CTX-M β-lactamases and their promoter regions from Enterobacteriaceae isolated in three Parisian hospitals
FEMS Microbiol Lett
 , 
2002
, vol. 
209
 (pg. 
161
-
8
)
45
Arpin
C
Dubois
V
Coulange
L
, et al.  . 
Extended-spectrum β-lactamase-producing Enterobacteriaceae in community and private health care centers
Antimicrob Agents Chemother
 , 
2003
, vol. 
47
 (pg. 
3506
-
14
)
46
Kassis-Chikhani
N
Vimont
S
Asselat
K
, et al.  . 
CTX-M β-lactamase-producing Escherichia coli in long-term care facilities, France
Emerg Infect Dis
 , 
2004
, vol. 
10
 (pg. 
1697
-
8
)
47
Lartigue
MF
Fortineau
N
Nordmann
P
Spread of novel expanded-spectrum β-lactamases in Enterobacteriaceae in a university hospital in the Paris area, France
Clin Microbiol Infect
 , 
2005
, vol. 
11
 (pg. 
588
-
91
)
48
Lartigue
MF
Poirel
L
Decousser
JW
, et al.  . 
Multidrug-resistant Shigella sonnei and Salmonella enterica serotype Typhimurium isolates producing CTX-M β-lactamases as causes of community-acquired infection in France
Clin Infect Dis
 , 
2005
, vol. 
40
 (pg. 
1069
-
70
)
49
Leflon-Guibout
V
Jurand
C
Bonacorsi
S
, et al.  . 
Emergence and spread of three clonally related virulent isolates of CTX-M-15-producing Escherichia coli with variable resistance to aminoglycosides and tetracycline in a French geriatric hospital
Antimicrob Agents Chemother
 , 
2004
, vol. 
48
 (pg. 
3736
-
42
)
50
Eckert
C
Gautier
V
Saladin-Allard
M
, et al.  . 
Dissemination of CTX-M-type β-lactamases among clinical isolates of Enterobacteriaceae in Paris, France
Antimicrob Agents Chemother
 , 
2004
, vol. 
48
 (pg. 
1249
-
55
)
51
de Champs
C
Chanal
C
Sirot
D
, et al.  . 
Frequency and diversity of Class A extended-spectrum β-lactamases in hospitals of the Auvergne, France: a 2 year prospective study
J Antimicrob Chemother
 , 
2004
, vol. 
54
 (pg. 
634
-
9
)
52
Lavigne
JP
Bouziges
N
Chanal
C
, et al.  . 
Molecular epidemiology of Enterobacteriaceae isolates producing extended-spectrum β-lactamases in a French hospital
J Clin Microbiol
 , 
2004
, vol. 
42
 (pg. 
3805
-
8
)
53
Lavigne
JP
Marchandin
H
Delmas
J
, et al.  . 
qnrA in CTX-M-producing Escherichia coli from France
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
4224
-
8
)
54
Weill
FX
Lailler
R
Praud
K
, et al.  . 
Emergence of extended-spectrum-β-lactamase (CTX-M-9)-producing multiresistant strains of Salmonella enterica serotype Virchow in poultry and humans in France
J Clin Microbiol
 , 
2004
, vol. 
42
 (pg. 
5767
-
73
)
55
Baquero
F
Reguera
JA
Ojeda
M
, et al.  . 
M. Escherichia coli con resistaencia a cefalosporinas de 3a generacion codificada por β-lactamasas de tipo plasmidico: primer brote en Espãna
Rev Esp Microbiol Clin
 , 
1988
, vol. 
3
 (pg. 
581
-
2
)
56
Fernandez-Rodriguez
A
Canton
R
Perez-Diaz
JC
, et al.  . 
Aminoglycoside-modifying enzymes in clinical isolates harboring extended-spectrum β-lactamases
Antimicrob Agents Chemother
 , 
1992
, vol. 
36
 (pg. 
2536
-
8
)
57
Fernandez-Rodriguez
A
Reguera
JA
Perez-Diaz
JC
, et al.  . 
Primera epidemia en espanola de resistencia plasmidica a cefalosporinas de tercera generacion: implicacion de SHV-2
Enferm Infecc Microbiol Clin
 , 
1992
, vol. 
10
 (pg. 
456
-
61
)
58
Simarro
E
Navarro
F
Ruiz
J
, et al.  . 
Salmonella enterica serovar Virchow with CTX-M-like β-lactamase in Spain
J Clin Microbiol
 , 
2000
, vol. 
38
 (pg. 
4676
-
8
)
59
Sabate
M
Tarrago
R
Navarro
F
, et al.  . 
Cloning and sequence of the gene encoding a novel cefotaxime-hydrolyzing β-lactamase (CTX-M-9) from Escherichia coli in Spain
Antimicrob Agents Chemother
 , 
2000
, vol. 
44
 (pg. 
1970
-
3
)
60
Oliver
A
Perez-Diaz
JC
Coque
TM
, et al.  . 
Nucleotide sequence and characterization of a novel cefotaxime-hydrolyzing β-lactamase (CTX-M-10) isolated in Spain
Antimicrob Agents Chemother
 , 
2001
, vol. 
45
 (pg. 
616
-
20
)
61
Coque
TM
Oliver
A
Perez-Diaz
JC
, et al.  . 
Genes encoding TEM-4, SHV-2, and CTX-M-10 extended-spectrum β-lactamases are carried by multiple Klebsiella pneumoniae clones in a single hospital (Madrid, 1989 to 2000)
Antimicrob Agents Chemother
 , 
2002
, vol. 
46
 (pg. 
500
-
10
)
62
Valverde
A
Coque
TM
Sanchez-Moreno
MP
, et al.  . 
Dramatic increase in prevalence of fecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae during nonoutbreak situations in Spain
J Clin Microbiol
 , 
2004
, vol. 
42
 (pg. 
4769
-
75
)
63
Coque
TM
Varela
M del C
Oliver
A
, et al.  . 
Shifting epidemiology of extended-spectrum β-lactamase (ESBL) in a Spanish hospital (1988–2000): from SHV to CTX-M-derived ESBL
1988
Abstracts of the Forty-first Interscience Conference on Antimicrobial Agents and Chemotherapy
2001
Chicago
Washington, DC, USA
American Society for Microbiology
pg. 
118
  
Abstract C2-298
64
Sabate
M
Miro
E
Navarro
F
, et al.  . 
β-Lactamases involved in resistance to broad-spectrum cephalosporins in Escherichia coli and Klebsiella spp. clinical isolates collected between 1994 and 1996, in Barcelona (Spain)
J Antimicrob Chemother
 , 
2002
, vol. 
49
 (pg. 
989
-
97
)
65
Romero
L
Lopez
L
Rodriguez-Bano
J
, et al.  . 
Long-term study of the frequency of Escherichia coli and Klebsiella pneumoniae isolates producing extended-spectrum β-lactamases
Clin Microbiol Infect
 , 
2005
, vol. 
11
 (pg. 
625
-
31
)
66
Rodriguez-Bano
J
Navarro
MD
Romero
L
, et al.  . 
Epidemiology and clinical features of infections caused by extended-spectrum β-lactamase-producing Escherichia coli in nonhospitalized patients
J Clin Microbiol
 , 
2004
, vol. 
42
 (pg. 
1089
-
94
)
67
Hernandez
JR
Pascual
A
Canton
R
, et al.  . 
Aislamiento de Escherichia coli y Klebsiella pneumoniae productores de β-lactamases de espectro extendido en hospitales espanoles
Enferm Infecc Microbiol Clin
 , 
2003
, vol. 
21
 (pg. 
77
-
82
)
68
Hernandez
JR
Martinez-Martinez
L
Canton
R
, et al.  . 
Nationwide study of Escherichia coli and Klebsiella pneumoniae producing extended-spectrum β-lactamases in Spain
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
2122
-
5
)
69
Mirelis
B
Navarro
F
Miro
E
, et al.  . 
Community transmission of extended-spectrum β-lactamase
Emerg Infect Dis
 , 
2003
, vol. 
9
 (pg. 
1024
-
5
)
70
Oteo
J
Navarro
C
Cercenado
E
, et al.  . 
Spread of Escherichia coli strains with high-level cefotaxime and ceftazidime resistance between the community, long-term care facilities, and hospital institutions
J Clin Microbiol
 , 
2006
, vol. 
44
 (pg. 
2359
-
66
)
71
Baquero
F
Coque
TM
Canton
R
Allodemics
Lancet Infect Dis
 , 
2002
, vol. 
2
 (pg. 
591
-
2
)
72
Prats
G
Mirelis
B
Miro
E
, et al.  . 
Cephalosporin-resistant Escherichia coli among summer camp attendees with salmonellosis
Emerg Infect Dis
 , 
2003
, vol. 
9
 (pg. 
1273
-
80
)
73
Bou
G
Cartelle
M
Tomas
M
, et al.  . 
Identification and broad dissemination of the CTX-M-14 β-lactamase in different Escherichia coli strains in the northwest area of Spain
J Clin Microbiol
 , 
2002
, vol. 
40
 (pg. 
4030
-
6
)
74
Brinas
L
Moreno
MA
Teshager
T
, et al.  . 
Monitoring and characterization of extended-spectrum β-lactamases in Escherichia coli strains from healthy and sick animals in Spain in 2003
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
1262
-
4
)
75
Romero
L
Lopez
L
Martinez-Martinez
L
, et al.  . 
Characterization of the first CTX-M-14-producing Salmonella enterica serotype Enteritidis isolate
J Antimicrob Chemother
 , 
2004
, vol. 
53
 (pg. 
1113
-
4
)
76
Miro
E
Mirelis
F
Navarro
F
, et al.  . 
ESBL in Escherichia coli: increase in prevalence and diversity
Clin Microbiol Infect
 , 
2005
, vol. 
11
 
Suppl 2
pg. 
118
  
Abstract P461
77
Rodriguez-Bano
J
Navarro
MD
Romero
L
, et al.  . 
Clinical and molecular epidemiology of extended-spectrum β-lactamase-producing Escherichia coli as a cause of nosocomial infection or colonization: implications for control
Clin Infect Dis
 , 
2006
, vol. 
42
 (pg. 
37
-
45
)
78
Colodner
R
Rock
W
Chazan
B
, et al.  . 
Risk factors for the development of extended-spectrum β-lactamase-producing bacteria in non hospitalized patients
Eur J Clin Microbiol Infect Dis
 , 
2004
, vol. 
23
 (pg. 
163
-
7
)
79
Novais
A
Canton
R
Valverde
A
, et al.  . 
Dissemination and persistence of blaCTX-M-9 are linked to class 1 integrons containing CR1 associated with defective transposon derivatives from Tn402 located in early antibiotic resistance plasmids of IncHI2, IncP1-α, and IncFI groups
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
2741
-
50
)
80
Machado
E
Canton
R
Baquero
F
, et al.  . 
Integron content of extended-spectrum-β-lactamase-producing Escherichia coli strains over 12 years in a single hospital in Madrid, Spain
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
1823
-
9
)
81
Oliver
A
Coque
TM
Alonso
D
, et al.  . 
CTX-M-10 linked to a phage-related element is widely disseminated among Enterobacteriaceae in a Spanish hospital
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
1567
-
71
)
82
Spanu
T
Luzzaro
F
Perilli
M
, et al.  . 
Occurrence of extended-spectrum β-lactamases in members of the family Enterobacteriaceae in Italy: implications for resistance to β-lactams and other antimicrobial drugs
Antimicrob Agents Chemother
 , 
2002
, vol. 
46
 (pg. 
196
-
202
)
83
Sanguinetti
M
Posteraro
B
Spanu
T
, et al.  . 
Characterization of clinical isolates of Enterobacteriaceae from Italy by the BD Phoenix extended-spectrum β-lactamase detection method
J Clin Microbiol
 , 
2003
, vol. 
41
 (pg. 
1463
-
8
)
84
Pagani
L
Dell'Amico
E
Migliavacca
R
, et al.  . 
Multiple CTX-M-type extended-spectrum β-lactamases in nosocomial isolates of Enterobacteriaceae from a hospital in northern Italy
J Clin Microbiol
 , 
2003
, vol. 
41
 (pg. 
4264
-
9
)
85
Luzzaro
F
Mezzatesta
M
Mugnaioli
C
, et al.  . 
Trends in production of extended-spectrum β-lactamases among enterobacteria of medical interest: report of the second Italian nationwide survey
J Clin Microbiol
 , 
2006
, vol. 
44
 (pg. 
1659
-
64
)
86
Mugnaioli
C
Luzzaro
F
De Luca
F
, et al.  . 
CTX-M-type extended-spectrum β-lactamases in Italy: molecular epidemiology of an emerging countrywide problem
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
2700
-
6
)
87
Brigante
G
Luzzaro
F
Perilli
M
, et al.  . 
Evolution of CTX-M-type β-lactamases in isolates of Escherichia coli infecting hospital and community patients
Int J Antimicrob Agents
 , 
2005
, vol. 
25
 (pg. 
157
-
62
)
88
Mugnaioli
C
Luzzaro
F
De Luca
F
, et al.  . 
Dissemination of CTX-M-type extended-spectrum β-lactamase genes to unusual hosts
J Clin Microbiol
 , 
2005
, vol. 
43
 (pg. 
4183
-
5
)
89
Carattoli
A
Lovari
S
Franco
A
, et al.  . 
Extended-spectrum β-lactamases in Escherichia coli isolated from dogs and cats in Rome, Italy, from 2001 to 2003
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
833
-
5
)
90
Gniadkowski
M
Schneider
I
Palucha
A
, et al.  . 
Cefotaxime-resistant Enterobacteriaceae isolates from a hospital in Warsaw, Poland: identification of a new CTX-M-3 cefotaxime-hydrolyzing β-lactamase that is closely related to the CTX-M-1/MEN-1 enzyme
Antimicrob Agents Chemother
 , 
1998
, vol. 
42
 (pg. 
827
-
32
)
91
Bauernfeind
A
Grimm
H
Schweighart
S
A new plasmidic cefotaximase in a clinical isolate of Escherichia coli
Infection
 , 
1990
, vol. 
18
 (pg. 
294
-
8
)
92
Barthelemy
M
Peduzzi
J
Bernard
H
, et al.  . 
Close amino acid sequence relationship between the new plasmid-mediated extended-spectrum β-lactamase MEN-1 and chromosomally encoded enzymes of Klebsiella oxytoca
Biochim Biophys Acta
 , 
1992
, vol. 
1122
 (pg. 
15
-
22
)
93
Palucha
A
Mikiewicz
B
Hryniewicz
W
, et al.  . 
Concurrent outbreaks of extended-spectrum β-lactamase-producing organisms of the family Enterobacteriaceae in a Warsaw hospital
J Antimicrob Chemother
 , 
1999
, vol. 
44
 (pg. 
489
-
99
)
94
Baraniak
A
Fiett
J
Sulikowska
A
, et al.  . 
Countrywide spread of CTX-M-3 extended-spectrum β-lactamase-producing microorganisms of the family Enterobacteriaceae in Poland
Antimicrob Agents Chemother
 , 
2002
, vol. 
46
 (pg. 
151
-
9
)
95
Baraniak
A
Sadowy
E
Hryniewicz
W
, et al.  . 
Two different extended-spectrum β-lactamases (ESBLs) in one of the first ESBL-producing salmonella isolates in Poland
J Clin Microbiol
 , 
2002
, vol. 
40
 (pg. 
1095
-
7
)
96
Baraniak
A
Fiett
J
Hryniewicz
W
, et al.  . 
Ceftazidime-hydrolysing CTX-M-15 extended-spectrum β-lactamase (ESBL) in Poland
J Antimicrob Chemother
 , 
2002
, vol. 
50
 (pg. 
393
-
6
)
97
Gierczynski
R
Szych
J
Rastawicki
W
, et al.  . 
The molecular characterisation of the extended spectrum β-lactamase (ESBL) producing strain of Salmonella enterica serovar Mbandaka isolated in Poland
Acta Microbiol Pol
 , 
2003
, vol. 
52
 (pg. 
183
-
90
)
98
Gierczynski
R
Szych
J
Cieslik
A
, et al.  . 
The occurrence of the first two CTX-M-3 and TEM-1 producing isolates of Salmonella enterica serovar Oranienburg in Poland
Int J Antimicrob Agents
 , 
2003
, vol. 
21
 (pg. 
497
-
9
)
99
Damjanova
I
Toth
A
Paszti
J
, et al.  . 
Nationwide spread of clonally related CTX-M-15-producing multidrug-resistant Klebsiella pneumoniae strains in Hungary
Eur J Clin Microbiol Infect Dis
 , 
2006
, vol. 
25
 (pg. 
275
-
8
)
100
Tzelepi
E
Magana
C
Platsouka
E
, et al.  . 
Extended-spectrum β-lactamase types in Klebsiella pneumoniae and Escherichia coli in two Greek hospitals
Int J Antimicrob Agents
 , 
2003
, vol. 
21
 (pg. 
285
-
8
)
101
Markovska
R
Keuleyan
E
Schneider
I
, et al.  . 
CTX-M-3 extended-spectrum β-lactamase-producing Klebsiella pneumoniae and dissemination of the plasmidic blaCTX-M-3 in Bulgaria
Eur J Clin Microbiol Infect Dis
 , 
2006
, vol. 
25
 (pg. 
123
-
5
)
102
Zarnayova
M
Siebor
E
Pechinot
A
, et al.  . 
Survey of Enterobacteriaceae producing extended-spectrum β-lactamases in a Slovak hospital: dominance of SHV-2a and characterization of TEM-132
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
3066
-
9
)
103
Eisner
A
Fagan
EJ
Feierl
G
, et al.  . 
Emergence of Enterobacteriaceae isolates producing CTX-M extended-spectrum β-lactamase in Austria
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
785
-
7
)
104
Rodriguez-Villalobos
H
Malaviolle
V
Frankard
J
, et al.  . 
In vitro activity of temocillin against extended spectrum β-lactamase-producing Escherichia coli
J Antimicrob Chemother
 , 
2006
, vol. 
57
 (pg. 
771
-
4
)
105
Haldorsen
B
Natas
O
Grundt
H
, et al.  . 
A nosocomial outbreak of CTX-M-15 producing E. coli in Norway
Clin Microbiol Infect
 , 
2005
, vol. 
11
 
Suppl 2
pg. 
111
  
Abstract 440
106
Fang
H
Lundberg
C
Olsson-Liljequist
B
, et al.  . 
Molecular epidemiological analysis of Escherichia coli isolates producing extended-spectrum β-lactamases for identification of nosocomial outbreaks in Stockholm, Sweden
J Clin Microbiol
 , 
2004
, vol. 
42
 (pg. 
5917
-
20
)
107
Conceicao
T
Brizio
A
Duarte
A
, et al.  . 
First description of CTX-M-15-producing Klebsiella pneumoniae in Portugal
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
477
-
8
)
108
Karim
A
Poirel
L
Nagarajan
S
, et al.  . 
Plasmid-mediated extended-spectrum β-lactamase (CTX-M-3 like) from India and gene association with insertion sequence ISEcp1
FEMS Microbiol Lett
 , 
2001
, vol. 
201
 (pg. 
237
-
41
)
109
Lartigue
MF
Poirel
L
Heritier
C
, et al.  . 
First description of CTX-M-15-producing Klebsiella pneumoniae in Turkey
J Antimicrob Chemother
 , 
2003
, vol. 
52
 (pg. 
315
-
6
)
110
Gangoue-Pieboji
J
Miriagou
V
Vourli
S
, et al.  . 
Emergence of CTX-M-15-producing enterobacteria in Cameroon and characterization of a blaCTX-M-15-carrying element
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
441
-
3
)
111
Yan
JJ
Ko
WC
Tsai
SH
, et al.  . 
Dissemination of CTX-M-3 and CMY-2 β-lactamases among clinical isolates of Escherichia coli in southern Taiwan
J Clin Microbiol
 , 
2000
, vol. 
38
 (pg. 
4320
-
5
)
112
Naas
T
Lezzar
A
Bentchouala
C
, et al.  . 
Multidrug-resistant Salmonella enterica serotype Senftenberg isolates producing CTX-M β-lactamases from Constantine, Algeria
J Antimicrob Chemother
 , 
2005
, vol. 
56
 (pg. 
439
-
40
)
113
Lavollay
M
Mamlouk
K
Frank
T
, et al.  . 
Clonal dissemination of a CTX-M-15 β-lactamase-producing Escherichia coli strain in the Paris area, Tunis, and Bangui
Antimicrob Agents Chemother
 , 
2006
, vol. 
50
 (pg. 
2433
-
8
)
114
Chmelnitsky
I
Carmeli
Y
Leavitt
A
, et al.  . 
CTX-M-2 and a new CTX-M-39 enzyme are the major extended-spectrum β-lactamases in multiple Escherichia coli clones isolated in Tel Aviv, Israel
Antimicrob Agents Chemother
 , 
2005
, vol. 
49
 (pg. 
4745
-
50
)
115
Phillips
I
King
A
Gransden
WR
, et al.  . 
The antibiotic sensitivity of bacteria isolated from the blood of patients in St Thomas' Hospital, 1969–1988
J Antimicrob Chemother
 , 
1990
, vol. 
25
 
Suppl C
(pg. 
59
-
80
)