Quinolone resistance among Salmonella enterica and Escherichia coli in Lithuania

Abstract

Lithuanian isolates of Escherichia coli and Salmonella enterica from animals and humans were examined for resistance to quinolones, fluoroquinolones and for resistance-associated mutations. 9% of S. enterica from animals and 4% of isolates from clinical samples of humans were resistant to nalidixic acid and susceptible to fluoroquinolones. DNA analysis of nalidixic acid-resistant S.enterica strains from animals revealed a single mutation at codon 83 (Ser→Phe) in gyrA gene, whereas resistant clinical strains contained a single gyrA mutation at codon 87 (Asp→Tyr). 10% of human isolates of E. coli were resistant to nalidixic acid and ciprofloxacin. 22% of E. coli isolates from calves were resistant to nalidixic acid. 40% and 20% of E. coli isolates from pigs were resistant to nalidixic acid and to fluoroquinolones, respectively. E. coli isolates of animal and human origin analyzed for nalidixic acid resistance-associated mutations carried single mutations at codon 83 (Ser→Leu) or at codon 87 (Asp→Tyr) in gyrA gene. Fluoroquinolone-resistant E. coli isolates from calves and humans carried multiple mutations within gyrA (83Ser→Leu, 87Asp→Gly or Asn) and parC (80Ser→Ile or Arg, 84Glu→Val or Lys) genes. Keywords: Escherichia coli, Salmonella enterica, quinolone resistance, gyrA, parC