Appearance of aac(6')-Ib-cr gene among extended-spectrum beta-lactamase-producing Enterobacteriaceae in a French hospital.
OBJECTIVE
The aac(6')-Ib gene encodes many variants of an aminoglycoside-acetyltransferase enzyme that is responsible for amikacin resistance. Recently, a new variant aac(6')-Ib-cr capable of modifying aminoglycosides and fluoroquinolones has been described. The aim of our study was to observe the appearance and the location of the aac(6')-Ib gene in extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae strains.


METHODS
Sixty-six and nine non-clonal ESBL-producing Enterobacteriaceae strains were isolated, respectively, for one 3-year period from 1999 to 2001 and one 2-month period in 2005 in a French Hospital (Paris, France).


RESULTS
Among these isolates, 35 of them carried the aac(6')-Ib gene. Fourteen out of the aac(6')-Ib genes of the period 1 and two of the period 2 were genes cassette located within class 1 integrons, whereas 16 and 3, respectively, were outside integrons. One of these encoded an aminoglycoside-acetyltransferase enzyme leading to an acetyltransferase that confers resistance to all aminoglycosides. The new -cr variant of aac(6')-Ib was detected in three Escherichia coli isolates in 2005 always associated with CTX-M-15 enzyme.


CONCLUSIONS
The aac(6')-Ib-cr gene, responsible for antibiotic resistance to two very different drugs, is emerging in ESBL-producing Enterobacteriaceae strains isolated in France especially in strains carrying the bla(CTx-M-15) gene.
Fihman
V
V
Service de Bactériologie-Virologie, Hôpital Lariboisière, Assistance Publique Hôpitaux de Paris, Université Paris VII, 2, rue Ambroise Paré, 75475 Paris, France.
Lartigue
M F
MF
Jacquier
H
H
Meunier
F
F
Schnepf
N
N
Raskine
L
L
Riahi
J
J
Sanson-le Pors
M-J
MJ
Berçot
B
B
D000123:Acetyltransferases / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D005602:France / Q000453:epidemiology; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D047090:beta-Lactams; D000123:Acetyltransferases; C019681:aminoglycoside acetyltransferase; D001618:beta-Lactamases