Analysis of plasmid-mediated quinolone resistance determinants among ESBL-producing Enterobacteriaceae in Belgium

Abstract number: P1328

Rodriguez-Villalobos H., de Mendonça R., Bogaerts P., Cardentey-Reyes A., Montesinos I., Cardona C., Deplano A., Struelens M.J., Glupczynski Y.

Objectives: Plasmid-mediated quinolone resistance determinants are widespread among ESBL-producing organisms enhancing selection and transmission of multiresistance. qnr genes have not yet been reported in clinical isolates from Belgium. We evaluated the prevalence of Qnr determinants in ESBL-producing isolates.

Methods: 117 ESBL-producing clinical isolates recovered from January 2000 to December 2007 at Erasme University Hospital (Brussels) with MIC of ceftazimime >8 mg/L and MIC of ciprofloxacin >0.25 mg/L were studied. Isolates included E. coli (n = 43), K. pneumoniae (n = 42), E. cloacae (n = 17), E. aerogenes (n = 9), S. marcescens (n = 2), P. mirabilis (n = 2) and Providencia spp.(n = 2). The presence of ESBL was confirmed by double combination disk test. ESBLs were characterized by PCR-sequencing assay. Qnr genes were analysed by multiplex PCR targeting blaqnrA, blaqnrB, blaqnrS and sequencing. The genetic environment of qnr genes was analysed by PCR mapping and sequencing. Clonality was assessed by PFGE. Conjugation assay was performed with E. coli J53 azide resistant as recipient strain.

Results: qnr genes were found in 37 isolates (32%). Only 1 CTX-M-15-producing E. coli isolate harboured qnrS1 (2%). Seventeen E. cloacae harboured qnrA1 (100%). These strains co-produced CTX-M-9 and SHV-12 (n = 15) or CTX-M-9 alone (n = 2). qnrA gene was present into a complex class 1 integron being flanked upstream by Orf 513 (ISCR1) and downstream by qacEdelta1 genetic elements (qac/sul 3' end). No transconjugants were obtained neither from E. coli nor E. cloacae. 19/42 (45%) CTX-M-15 producing K. pneumoniae showed qnr genes (17 qnrS1 and 2 qnrB). These strains belong to a major epidemic clone in ICU. The analysis of transconjugants showed that blaqnrS1 was transferred with or without blaCTX-M-15, suggesting the location of qnr genes in different plasmids. blaqnrB was co-transferred with blaCTX-M-15. No qnr were found in the other species. Susceptibility to quinolones varied according to qnr type and host species.

Conclusion: This is the first description of qnr genes in ESBL-producing Enterobacteriaceae clinical isolates in Belgium. Our findings show a high prevalence of qnr genes among epidemic ESBL-producing E. cloacae and K. pneumoniae. They underline the need for caution in using quinolones for treatment of ESBL producers. Further study will examine the spread of qnr genes in other Belgian hospitals.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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