SALMONELLA-TYPHIMURIUM GYRA MUTATIONS ASSOCIATED WITH FLUOROQUINOLONERESISTANCE

Spontaneous quinolone-resistant mutants obtained from Salmonella typhi murium Su694 were screened for mutations by direct DNA sequencing of a n amplified PCR gyrA fragment. Substitutions Ser-83-->Phe (Ser83Phe), Ser83Tyr, Asp87Tyr, and Asp87Asn and double mutation Ala67Pro-Gly81Ser , which resulted in decreased sensitivities to ciprofloxacin, enoxacin , pefloxacin, norfloxacin, ofloxacin, and nalidixic acid, were found. The levels of resistance to quinolones for each mutant were determined .