Molecular Detection of qnrA, qnrB and qnrS Resistance Genes among Salmonella spp. in Iran

Abstract

Prevalence of three plasmid-mediated quinolone resistance determinant qnrA, qnrB, qnrS and extended spectrum Cephalosporins determinant blaCMY, among eighty-five isolates of Salmonella spp. collected in the community between 2008 and 2010 was determined by PCR. Not only qnr genes but also bla genes were positive in twenty-four different isolates. PCR assay detected that 22 of 85 (25.8%) Salmonella spp. carried the qnrA, 1 (1.17%) of 85 isolates harbored the qnrB, 1 (1.17%) of them contained the qnrS, 1 (1.17%) isolate carried all the three qnrA, qnrB, qnrS genes, 24 of 85 (28.2%) Salmonella carried blaCMY and 5 (5.88%) isolates carried qnrA and blaCMY. Antimicrobial susceptibility patterns of isolates were as follows: 49 (57.6%) exhibited resistance to Nalidixic acid and none of them to Ciprofloxacin. 33 (38.82%) isolates exhibited resistance to Cephalosporins and 2 (2.35%) of them exhibited ESBL phenotype and 12 (14.1%) isolates resistance to Ampicilin. These results were confirmed by MIC determination test as well. Having detected qnr and bla genes suggested that these genes spread antibiotic resistance among pathogenic bacteria.