Mutations in gyrA gene of quinolone-resistant Salmonella serotypes isolated from humans and animals.

The quinolone resistance-determining regions (QRDRs) of the gyrA genes of quinolone-resistant clinical and veterinary salmonella isolates were sequenced. Substitutions analogous to a substitution of a Ser to a Phe at position 83 (Ser83-->Phe) and Asp87-->Gly or Tyr in Escherichia coli were found, as was a single novel mutation outside of the QRDR resulting in Ala119-->Glu. The data suggest that gyrA mutations are associated with quinolone resistance in veterinary and clinical salmonella isolates and that the limits of the QRDR may require revision.