engleski

Prevalence of qnr genes in 1032 invasive isolates of Escherichia coli in Croatia

PREVALENCE OF QNR GENES IN 1032 INVASIVE ISOLATES OF ESCHERICHIA COLI IN CROATIA M. Jelic1, M. Gu?vinec1, I. Butic1, S. Bukovski1, A. Tambic-Andra?evic1 1Department of Clinical Microbiology, University Hospital for Infectious Diseases, Zagreb, Croatia OBJECTIVES: To determine the prevalence of plasmid-mediated quinolone resistance (qnr) genes in all invasive isolates of Escherichia coli collected in Croatia during 2011. METHODS: During a 12 month period (1st January 2011 – 31st December 2011) 1032 invasive E. coli isolates were collected from inpatients in Croatian hospitals trough EARS-Net. Isolates were screened for presence of all reported alleles of qnrA, qnrB, qnrC, qnrD and qnrS genes by multiplex PCR, using a combination of primers designed in this study. Determination of qnr gene family was based on PCR product size evaluation by gel electrophoresis. Presence of respective genes was confirmed by DNA sequencing. Qnr-positive isolates were screened by PCR for presence of genes for class A β- lactamases, metallo- β-lactamases and plasmid AmpC. Antimicrobial susceptibility testing was performed by disc diffusion method to amoxicillin, gentamicin, amikacin, ciprofloxacin, ceftriaxone, ceftazidime, imipenem and meropenem. Clonal relatedness of qnr-positive strains was determined by Pulsed-field-gel electrophoresis of XbaI digested genomic DNA.The assignment of the E. coli phylogenetic group was carried out by multiplex PCR assay. RESULTS: Eighteen E. coli (18/1032, 1.74%) isolates were positive for qnr determinants (1 qnrA, 5 qnrB, 12 qnrS). Seven qnr positive isolates were non-susceptible to ciprofloxacin (1 qnrA, 1 qnrB, 5 qnrS) and only two were non-susceptible to 3rd generation cephalosporins (2 qnr S). TEM genes were detected in all isolates and CTX-M and SHV genes were detected in two isolates. Qnr positive isolates did not exhibit any apparent epidemiological relation. Isolates belonged to phylogenetic groups A, B1, B2 and D. CONCLUSIONS: Prevalence of plasmid mediated quinolone resistance in invasive isolates of E.coli is still low. Qnr positive isolates are clonally distinct and are detected in various parts of Croatia. Resistance to ciprofloxacin is not uniform for all qnr-positive isolates.

qnr; antimicrobial resistance; E. coli

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