Determinants of quinolone resistance in Escherichia coli causing community-acquired urinary tract infection in Bejaia, Algeria

Objective: To investigate the mechanisms of quinolone resistance and the association with other resistance markers among Esherichia coli(E. coli) strains isolated from outpatient with urinary tract infection in north of Algeria. Methods: A total of 30 nalidixic acid resistant E. coli isolates from outpatient with urinary tract infections from January 2010 to April 2011 in north of Algeria (Bejaia) were studied. Antimicrobial susceptibility was determined by disc diffusion assay, minimal inhibitory concentrations (MIC) of quinolone were determined by microdilution. Mutations in the Quinolone Resistance-Determining Region (QRDR) of gyrA and parC genes and screening for qnr (A, B and S) and bla genes were done by PCR and DNA sequencing. Results: Most of the E. coli isolates (56.66%) were shown to carry mutations in gyrA and parC (gyrA: Ser83Leu + Asp87Asn and parC:Ser80Ile). While, 16.66% had only an alteration in g)tA: Ser83Leu. One isolate produced qnrB like and two qnrS-like. Four isolates were CTX-M-15 producers associated with TEM-1 producing in one case. Co-expression of bla(crx-m-15) and qnrB was determined in one E. coli isolate. Conclusions: Our findings suggested the community emergence of gyrA and parC alterations and QnrB determinants that contributed to the development and spread of fluoroquinolone resistance in Algerian E. coli isolates.