In vitro analysis of ISEcp1B-mediated mobilization of naturally occurring beta-lactamase gene blaCTX-M of Kluyvera ascorbata.
ISEcp1B has been reported to be associated with and to mobilize the emerging expanded-spectrum beta-lactamase blaCTX-M genes in Enterobacteriaceae. Thus, the ability of this insertion sequence to mobilize the blaCTX-M-2 gene was tested from its progenitor, Kluyvera ascorbata. Insertions of ISEcp1B upstream of the blaCTX-M-2 gene in K. ascorbata reference strain CIP7953 were first selected with cefotaxime (0.5 and 2 microg/ml). In those cases, ISEcp1B brought promoter sequences enhancing blaCTX-M-2 expression in K. ascorbata. Then, ISEcp1B-mediated mobilization of the blaCTX-M-2 gene from K. ascorbata to Escherichia coli J53 was attempted. The transposition frequency of ISEcp1B-blaCTX-M-2 occurred at (6.4+/-0.5)x10(-7) in E. coli. Cefotaxime, ceftazidime, and piperacillin enhanced transposition, whereas amoxicillin, cefuroxime, and nalidixic acid did not. Transposition was also enhanced when studied at 40 degrees C.
Service de Bactériologie-Virologie, Hôpital de Bicêtre, Faculté de Médecine Paris-Sud, Université Paris, K.-Bicêtre, France.
Marie-Frédérique
MF
Lartigue
Laurent
L
Poirel
Daniel
D
Aubert
Patrice
P
Nordmann
D004251:DNA Transposable Elements / Q000502:physiology*; D044086:Kluyvera / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D001618:beta-Lactamases / Q000235:genetics*
D004251:DNA Transposable Elements; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases