title: Beta-lactam induction of ISEcp1B-mediated mobilization of the naturally occurring bla(CTX-M) beta-lactamase gene of Kluyvera ascorbata.
abstract: ISEcp1B is an insertion element associated with the emerging expanded-spectrum beta-lactamase bla(CTX-M) genes in Enterobacteriaceae. Because ISEcp1B-bla(CTX-M)positive strains may be identified from humans and animals, the ability of this insertion sequence to mobilize the bla(CTX-M-2) gene was tested from its progenitor Kluyvera ascorbata to study the effects of amoxicillin/clavulanic and cefquinome as enhancers of transposition. These beta-lactam molecules are administered parenterally to treat infected animals. ISEcp1B-mediated mobilization of the bla(CTX-M-2) gene from K. ascorbata to a plasmid location in Escherichia coli J53 was studied. Transposition assays were performed with overnight cultures with amoxicillin/clavulanic acid and cefquinome at concentrations expected to mimic those found in feces after parenteral administration (0.4-0.008 mg L(-1) and 0.32-0.064 mg L(-1), respectively). Amoxicillin/clavulanic acid and cefquinome did not modify the transposition frequency (1.85+/-1.7 x 10(-7)) whereas ceftazidime (0.5 mg L(-1)), used as a control, did (5.2+/-2.7 x 10(-5)). Therefore, it is likely that neither amoxicillin/clavulanic acid nor cefquinome concentrations as found in the gut flora may enhance mobilization of the bla(CTX-M) genes in Enterobacteriaceae.
authors.affiliation: Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, INSERM U 914, and Faculté de Médecine et Université Paris-Sud, Le-Kremlin-Bicêtre, France. nordmann.patrice@bct.aphp.fr
authors.forename: Patrice
authors.initials: P
authors.lastname: Nordmann
authors.forename: Marie-Frédérique
authors.initials: MF
authors.lastname: Lartigue
authors.forename: Laurent
authors.initials: L
authors.lastname: Poirel
mesh_terms: D000818:Animals; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D044086:Kluyvera / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D010957:Plasmids / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D004251:DNA Transposable Elements; D047090:beta-Lactams; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases