Epidemiology of Extended-Spectrum β-Lactamase-Producing Enterobacter Isolates in a Spanish Hospital during a 12-Year Period

Abstract

Fifteen Enterobacter clinical isolates (11 Enterobacter cloacae isolates, 3 Enterobacter aerogenes isolates, and 1 Enterobacter gergoviae isolate), representing 0.4% of all Enterobacter isolates recovered in our hospital from 1989 to 2000, were suspected of harboring an extended-spectrum ␤-lactamase (ESBL). These isolates were recovered from 14 different patients. ESBLs were transferred by conjugation into an Escherichia coli recipient strain. Pulsed-field gel electrophoresis (PFGE) revealed a single clone of E. aerogenes and six different clones of E. cloacae. Four of these E. cloacae clonal types were represented by only one isolate each, but the other two were represented by three and four isolates, respectively. Isoelectric focusing, susceptibility phenotyping, PCR analysis, and sequencing demonstrated the presence of three different ESBLs. The most frequent was the recently characterized CTX-M-10 ESBL, which was found in the E. gergoviae isolate and in all but one of the E. cloacae isolates. The remaining E. cloacae isolate harbored a TEM-27 ESBL, and the three E. aerogenes isolates harbored a TEM-24 ESBL. PFGE revealed that our E. aerogenes strain was indistinguishable from the French TEM-24-producing E. aerogenes endemic clone. Although a low prevalence of ESBL-producing Enterobacter isolates was found in our institution over a 12-year period, a diversity of nonepidemic E. cloacae clones was detected, as was the persistence of the CTX-M-10 ␤-lactamase. The presence of the TEM-24-producing E. aerogenes French clone in our institution also demonstrates the intercountry dissemination of ESBL-producing isolates.Plasmid-mediated extended-spectrum ␤-lactamases (ESBLs) were first reported in the mid-1980s (14, 15). Since then they have been responsible for several outbreaks caused by expanded-spectrum cephalosporin-resistant enterobacteria. Klebsiella pneumoniae and Escherichia coli are the most frequently involved organisms, and TEM-1-and SHV-1-derived ␤-lactamases are the most common ESBLs found in these species (25). These enzymes have also been reported at a much lower frequency among inducible AmpC ␤-lactamase-producing members of the family Enterobacteriaceae, such as Enterobacter spp., Citrobacter spp., Morganella morganii, and Serratia spp. (6,10,17,23,27,28,38). The most common ESBLs found in these species also belong to the TEM-and SHV-derived ␤-lactamases.Enterobacter species have been found to be one of the most important causes of nosocomial infections during the last few years (9, 30). These organisms have been associated with several outbreaks generally involving derepressed mutants overproducing their chromosomal ␤-lactamase or, more infrequently, expressing ESBL (7,10,23,30).The aims of this study were to establish the epidemiological relationship among all ESBL-producing Enterobacter isolates recovered in our institution over a decade, as well as to characterize the ESBLs expressed in these isolates and the plasmids harboring ESBL genes. In addition, we investigated if our ESBL-producing Entero...

Rapid and simple detection of bla CTX−M genes by multiplex PCR assay

“…Those methods which make possible the differentiation of different gene sequences to establish the epidemiology of these new ESBLs are particularly needed. PCR has been applied successfully to characterize bla CTX-M genes, but detection of all members from five groups required multiple PCRs with group-specific primers (Canton et al, 2002;Chanawong et al, 2002;Pitout et al, 2004) or consensus primers which only amplify few bla CTX-M alleles Saladin et al, 2002). Currently, sequencing is the only method for definitive identification of bla CTX-M genes, which is labourintensive, time-consuming and expensive.…”

Prevalence and Molecular Epidemiology of CTX-MExtended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae in RussianHospitals

“…The first organisms producing ␤-lactamases of this type were identified both as single and epidemic clinical isolates in very distant geographic regions (Germany and France and Argentina) in the early 1990s (3, 5, 7). More recently, a rapid increase in the proportion of multiple CTX-M variants to the TEM-and SHV-derived ESBLs has been reported in many hospitals in Spain (9,12,15,35) (14), and Korea (28). Furthermore, CTX-M ␤-lactamases, mainly types CTX-M-2 and CTX-M-3, were found to be widespread or even predominant ESBL types in several countries, including Argentina (31, 34; M. Galas, F. Pasteran, R. Melano, A. Petroni, G. Lopez, A. Corso, A. Rossi, et al, Abstr.…”

“…Isoelectric focusing is also inadequate, since the same isoelectric point can correspond to different ␤-lactamases. PCR has been used widely to detect bla CTX-M genes, but detection of all the known variants usually required multiple reactions with specific primers for different genes (12,14). Consensus CTX-M primers have also been described (13,36), but these primers were used for amplification of bla CTX-M genes from a limited number of isolates.…”

Exploring the Inhibition of CTX-M-9 by β-Lactamase Inhibitors and Carbapenems

“…CTX-M-9 ␤-lactamase was inactivated by sulbactam, tazobactam, clavulanate, meropenem, doripenem, ertapenem, and a 6-methylidene penem, penem 1. CTX-M enzymes are becoming one of the most prevalent extended-spectrum ␤-lactamases (ESBLs) (3,8,9,(30)(31)(32) in the world. The widespread dissemination of CTX-M ␤-lactamases, especially Escherichia coli ST131 possessing CTX-M-15, has had a significant impact on the treatment of hospital-and community-acquired infections caused by E. coli and other enteric bacilli (6, 7, 13, 23, 36, 41, 44-49, 55, 59).…”