Table 1.

GyrA and ParC mutations and fluoroquinolone susceptibility profiles of avian E. coli isolates

No. of isolatesMutation in:MIC range (μg/ml)a
GyrA proteinbParC genecNalCipEnrSar
18Ser83 → LeuAGC → AGT64–>2560.5 to 161–321–32
4Ser83 → LeuNone (wild type)>256124
3Ser83 → Leu; Asp87 → GlyAGC → AGT>256124–8
2Ser83 → Leu; Asp87 → GlyNone (wild type)>256122–4
2Ser83 → Leu; Asp87 → TyrAGC → AGT>256124–8
  • a MICs determined with agar plate dilution methods according to NCCLS guidelines (15, 16). Nal, nalidixic acid; Cip, ciprofloxacin; Enr, enrofloxacin; Sar, sarafloxacin.

  • b Amino acid substitution(s) in GyrA.

  • c Nucleotide substitution in the third position of the Ser58 codon.