Table 2.

Antimicrobial susceptibility and point mutation in DNA topoisomerase of nontyphoid Salmonella strains isolated from food animals and humans carrying blaCTX-M genea

StrainDDTEtest MIC (mg/liter)bPoint mutation within QRDR of:
AMPCTXCTX + CACAZCAZ + CAFEPATMFOXNALCIPgyrAparC
09-V06-15+>256>160.064<0.50.12516241.52560.125Asp87→AsnWild type
09-V06-16+>256>160.094<0.50.1916241.55120.25Asp87→AsnWild type
09-V06-20+>256>160.094<0.50.25242425120.25Asp87→AsnWild type
09-V06-21+>256>160.064<0.50.1916321.52560.125Asp87→AsnWild type
09-V06-22+>256>160.094<0.50.25162425120.25Asp87→AsnWild type
09-V06-23+>256>160.125<0.50.2524241.55120.25Asp87→AsnWild type
09-V06-25+>256>160.125<0.50.25162425120.25Asp87→TyrWild type
09-V06-28+>256>160.064240.12512161.51280.125Asp87→AsnWild type
09-V05-54+>256>160.094<0.50.1912241.52560.125Asp87→AsnWild type
09-V05-56+>256>160.094<0.50.1916241.55120.25Asp87→AsnWild type
09-V05-57+>256>160.094<0.50.1912241.55120.25Asp87→AsnWild type
09-V05-58+>256>160.094<0.50.1916241.55120.25Asp87→AsnWild type
09-V05-59+>256>160.094<0.50.1916241.55120.125Asp87→AsnWild type
09-G-022+>256>160.064<0.50.1916241.52560.125Asp87→AsnWild type
09-G-081+>256>160.094<0.50.1916241.55120.25Asp87→AsnWild type
09-G-004+>256>160.094<0.50.1916241.52560.125Asp87→AsnWild type
09-G-097+>256>160.094<0.50.1916241.55120.25Asp87→AsnWild type
09-G-063+>256>160.094<0.50.1912241.55120.25Asp87→AsnWild type
09-G-069+>256>160.0941.50.19631.52560.125Asp87→GlyWild type
09-G-076+>256>160.0941.50.19631.52560.125Asp87→GlyWild type
  • a Abbreviations: DDT, double disk diffusion test; Etest, Epsilometer test; QRDR, quinolone resistance-determining region; AMP, ampicillin; CTX, cefotaxime; CAZ, ceftazidime; ATM, aztreonam; FEP, cefepime; FOX, cefoxitin; CA, clavulanic acid; NAL, nalidixic acid; CIP, ciprofloxacin.

  • b MICs of ciprofloxacin and nalidixic acid were determined by agar dilution method following the CLSI guidelines.