Quinolone resistance among Salmonella Kentucky and Typhimurium isolates in Tunisia: First report of Salmonella Typhimurium ST34 in Africa and qnrB19 in Tunisia

Aims Characterization of quinolone‐resistant Salmonella Kentucky and Typhimurium isolates in Tunisia from various sources, detection of some PMQR genes, and the genetic relatedness. Methods A total of 1,404 isolates of S . Kentucky (n = 1,059) / S . Typhimurium (n = 345) from various sources from all over Tunisia were tested for quinolone resistance by disk diffusion method. Minimum inhibitory concentrations of nalidixic acid, ciprofloxacin, and ofloxacin were determined. Quinolone‐resistant isolates were screened for plasmid‐mediated quinolone‐resistance genes [qnrA, qnrB, qnrS , aac(6′)‐Ib‐cr , and qepA ] by PCR. Mutations in the quinolone resistance‐determining regions of the gyrA and parC genes were detected by PCR and DNA sequencing. Pulsed‐field gel electrophoresis and multilocus sequence typing were accomplished for isolates harboring plasmid‐mediated quinolone‐resistance genes. Results According to our selection criteria (NAL = resistance phenotype; CIP = resistant with diameter 0, or intermediate), only 63 S. Kentucky/41 S . Typhimurium isolates were investigated: 49% (5/104) were multidrug‐resistant. Two S . Typhimurium isolates harbored qnrB19 with different PFGE profiles. A mutation was detected in the gyrA gene for each of these two isolates. MLST revealed the presence of ST313 and ST34, an endemic sequence type. Conclusion Our study highlights the presence of quinolone multidrug‐resistant Salmonella in humans and animals in Tunisia. This is the first report of S. Typhimurium ST34 in Africa and qnrB19 in Tunisia.