First detection of the plasmid-mediated quinolone resistance in extended-spectrum b-lactamases producing Enterobacteriaceae isolated from in-and out-patients in Switzerland

Abstract number: P2091

Liassine N., Zulueta-Rodriguez P., Corbel C., Lascols C., Soussy C.J., Cambau E.

Objective: The aim of the present study was to determine the prevalence of plasmid-mediated quinolone resistance qnr genes in ESBL-producing enterobacteriaceae strains isolated in a private laboratory.

Methods: Identification and antimicrobial susceptibility testing were performed using the VITEK 2 system (bioMérieux SA). PCR detection for plasmid-mediated quinolone resistance was performed using primers amplifying intragenic fragments of qnrA, qnrB and qnrS. MICs of nalidixic acid and fluoroquinolones were determined for the qnr-positive isolates using the Etest method. ESBL characterisation was performed for qnr-positive isolates by PCR of the TEM, SHV and CTX-M genes.

Results: 156 non-duplicate ESBL-producing enterobacteriaceae isolated from April 2001 to February 2006 were analysed. They provided from 155 patients from whom 87 (56.1%) were outpatients and 68 (43.9%) in-patients. The sex ratio of patients was 112/43 (female/male). Bacterial specie distributed as follows: Escherichia coli (n = 125, 80%), Klebsiella pneumoniae (n = 23, 14%), Citrobacter freundii (n = 2), Klebsiella oxytoca (n = 2), Enterobacter cloacae (n = 1), Morganella morganii (n = 1), Proteus penneri (n = 1) and Salmonella enterica (n = 1). The global prevalence of qnr-positive isolates was 3.2% with five isolates harbouring a qnrB gene: two isolates of C. freundii with the qnrB4 allele, 2 isolates of K. pneumoniae with the qnrB4 allele and one isolate of E. coli with the qnrB2 allele. None of the isolates harboured qnrA or qnrS genes. These five isolates were coming from urines of four different patients of whom three were followed by private practitioners in the community setting. Four isolates presented a high level resistance to fluoroquinolones (MIC > 32 mg/L) and one C. freundii isolate showed a intermediate level of fluoroquinolone resistance (fluoroquinolone MIC below 8 mg/L). The main type of ESBL of qnr-positive isolates was CTX-M-15 (n = 3), followed by CTX-M-3 (n = 1) and CTX-M-9 (n = 1).

Conclusion: This is the first report of plasmid-mediated quinolone resistance from clinical isolates in Switzerland, in the hospital as well as in the community setting. Although a low prevalence of qnr determinants was observed among ESBL-producing enterobacteriaceae, dissemination of qnrB genes is already present in Switzerland.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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