Quinolone resistance among Salmonella enterica and Escherichia coli in Lithuania

Abstract

Lithuanian isolates of Escherichia coli and Salmonella enterica from animals andhumans were examined for resistance to quinolones, fluoroquinolones and forresistance-associated mutations. 9% of S. enterica from animals and 4% ofisolates from clinical samples of humans were resistant to nalidixic acid andsusceptible 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 mutationat codon 87 (Asp→Tyr). 10% of human isolates of E. coli were resistant tonalidixic acid and ciprofloxacin. 22% of E. coli isolates from calves wereresistant to nalidixic acid. 40% and 20% of E. coli isolates from pigs wereresistant to nalidixic acid and to fluoroquinolones, respectively. E. coli isolatesof animal and human origin analyzed for nalidixic acid resistance-associatedmutations carried single mutations at codon 83 (Ser→Leu) or at codon 87(Asp→Tyr) in gyrA gene. Fluoroquinolone-resistant E. coli isolates from calvesand humans carried multiple mutations within gyrA (83Ser→Leu, 87Asp→Glyor Asn) and parC (80Ser→Ile or Arg, 84Glu→Val or Lys) genes.