Prevalence of plasmid-mediated quinolone resistance determinants in ESBL Enterobacteriaceae clinical isolates over a 1-year period in a French hospital.
The prevalence of plasmid-mediated quinolone resistance (PMQR) determinants (qnrA, qnrB, qnrS, aac(6')-Ib-cr, and qepA) was investigated in a collection of 47 extended-spectrum β-lactamase (ESBL) producing enterobacterial isolates with reduced susceptibility to fluoroquinolones, recovered at Nantes University hospital, in 2006. qnr, aac(6')-Ib-cr, and qepA genes were screened by PCR, and positive results were subsequently confirmed by sequencing. The epidemiological relationship between positive isolates was studied by pulsed-field gel electrophoresis (PFGE). qnr-positive isolates were analyzed for antimicrobial susceptibility and presence of mutations in the quinolone resistance-determining region (QRDR) of gyrA and parC genes. ESBL genes were characterized by PCR and sequencing. Conjugation experiments were performed to determine whether the qnr-carrying plasmids were self-transferable. Two Klebsiella pneumoniae isolates (4.3%), not clonally related, harboured a qnrS1 gene, whereas no qnrA- or qnrB-positive isolate was detected. The aac(6')-Ib-cr gene was detected in 11 Escherichia coli and one K. pneumoniae isolates. None of the 47 isolates carried the qepA gene. ESBLs associated with QnrS1 were CTX-M-14 and CTX-M-15. The CTX-M-15 producing isolate was highly resistant to fluoroquinolones and harboured three mutations in the QRDR and two PMQR determinants (qnrS1 and aac(6')-Ib-cr). The CTX-M-14-producing isolate exhibited reduced susceptibility or resistance to fluoroquinolones without resistance to nalidixic acid. This strain harboured only a qnr gene on a single 170 kb transferable plasmid, without any mutation in the QRDR. In conclusion, our study showed that aac(6')-Ib-cr gene had occurred in multiclonal ESBL-producing enterobacterial isolates collected at Nantes University hospital in 2006, with a higher prevalence than qnr genes.
Crémet
L
L
Service de bactériologie-hygiène hospitalière, CHU de Nantes, 9, quai Moncousu, 44093 Nantes cedex 01, France.
Caroff
N
N
Dauvergne
S
S
Reynaud
A
A
Lepelletier
D
D
Corvec
S
S
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D003227:Conjugation, Genetic; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D005602:France / Q000453:epidemiology; D006785:Hospitals, University; D006801:Humans; D016133:Polymerase Chain Reaction; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D011815:R Factors / Q000235:genetics / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015363:Quinolones; D001618:beta-Lactamases; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase