IDENTIFICATION OF DNA GYRASE A MUTATIONS IN CIPROFLOXACIN-RESISTANT ISOLATES OF SALMONELLA-TYPHIMURIUM FROM MEN AND CATTLE IN GERMANY

Six multiply resistant isolates of Salmonella typhimurium var. copenha gen with high-level resistance to fluoroquinolones (e.g., MIC of cipro floxacin: 32 mu g/ml) were isolated from human patients (n = 3) and fr om cattle (n = 3). The isolates were examined by complementation tests using a set of broad-host-range plasmids, which carry either the gyrA (+) or the gyrB(+) genes or a combination of both from Escherichia col i K-12. The results indicated a combination of gyrA and gyrB mutations in all isolates. Subsequent direct sequencing of PCR-generated intern al DNA fragments of gyrA revealed an identical double mutation in all six isolates (Ser-83 --> Ala and Asp-87 --> Asn). In addition, the res ults of phenotypic (i.e., phagetype, biotype, serotype) and genotypic characterization [i.e., ribotyping and polymerase chain reaction finge rprinting (PCR-fingerprinting)] were identical for all six isolates an d were distinguishable from a quinolone-susceptible strain of the same serovar and an unrelated isolate of S. typhimurium. These data indica te the clonal identity of the fluoroquinolone-resistant strains of S. typhimurium isolated from men and cattle in Germany.