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

Eighty five isolates of Salmonella spp. collected from different provinces of Iran during the years 2008 to 2010, were screened for the qnrA, qnrB and qnrS genes by PCR. PCR assays detected 22 of 85 (25.8%) Salmonella spp. isolates carried the qnrA gene, 1 (1.17%) of 85 isolates harbored the qnrB and 1 (1.17%) of 85 isolates contained the qnrS gene and 1 isolate carried all the three qnrA, qnrB and qnrS genes. Resistance to quinolones and fluoroquinolones by these genes has been confirmed. Antimicrobial susceptibility patterns of isolates were as follow: 49 (57.6%) isolates exhibited resistance to nalidixic acid and none to ciprofloxacin. As expected, MIC assay confirmed these results. Having detected the qnr genes and consequently resistance to quinolones and fluoroquinolones in Salmonella isolates indicated that qnr genes are disseminating among Salmonella serovars.