title: Emergence and dominance of CTX-M-15 extended spectrum beta-lactamase among Escherichia coli isolates from children.
abstract: Of forty-seven extended-spectrum cephalosporin-resistant Escherichia coli isolates, collected from children at the Children's Hospital in 2006 (Tunis, Tunisia), we analyzed 32 isolates that were genotypically different by enterobacterial repetitive intergenic consensus -polymerase chain reaction. For all isolates, the double-disk diffusion test revealed synergy between clavulanate and cefotaxime and/or ceftazidime, suggesting the production of extended-spectrum beta-lactamases. Polymerase chain reaction experiments, performed on plasmid DNA, and sequencing revealed the presence of bla(TEM-1B) (26 isolates, 81%), bla(TEM-34(IRT-6)) (3 isolates, 9%), bla(SHV-12) (2 isolates, 6%), and bla(CTX-M-15) (31 isolates, 97%). Further, the insertion sequence ISEcp1 was found upstream from the bla(CTX-M-15) gene in 11 isolates. The bla genes were found alone or in various combinations in a single isolate. bla(TEM-1B) and bla(CTX-M-15) genes were detected in 26 out of the 32 isolates. Three isolates harbored both bla(TEM-34(IRT-6)) and bla(CTX-M-15). bla(SHV-12) was identified either alone or with bla(CTX-M-15) in a single isolate. Our investigation showed the dominance of CTX-M-type extended-spectrum beta-lactamases, with CTX-M-15 particularly common, and to our best knowledge, this is the first report of the coexistence of CTX-M-15 and IRT-6 in E. coli isolates from children in Tunisia.
authors.affiliation: Département des Sciences Biologiques, Faculté des Sciences de Tunis, Université Tunis El-Manar, Tunis, Tunisia. samia_biochimie@yahoo.fr
authors.forename: Samia
authors.initials: S
authors.lastname: Réjiba
authors.forename: Paola Sandra
authors.initials: PS
authors.lastname: Mercuri
authors.forename: Pablo
authors.initials: P
authors.lastname: Power
authors.forename: Amel
authors.initials: A
authors.lastname: Kechrid
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002439:Cefotaxime / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology; D002648:Child; D019818:Clavulanic Acid / Q000494:pharmacology; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000097:blood*; D021901:DNA, Intergenic / Q000032:analysis; D052978:Disk Diffusion Antimicrobial Tests; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000235:genetics* / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D014416:Tunisia; D001618:beta-Lactamases / Q000097:blood / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D021901:DNA, Intergenic; D019818:Clavulanic Acid; D002442:Ceftazidime; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases; D002439:Cefotaxime