Detection of fluoroquinolone resistance in Campylobacter strains from organic poultry

摘要

Studies have shown that resistance to quinolones in Campylobacter strains is related with Threonine-86-lsoleucine mutation. In order to investigate the presence of this mutation in sensitive and resistant Cam pylobacter strains to ciprofloxacin and enrofloxacin, the cecal contents of 80 broilers from organic raising chickens, slaughtered under State Inspection Service (S.I.S) of the State of Rio de Janeiro, were collected and tested for the presence of Cam pylobacter. The determination of ciprofloxacin and enrofloxacin susceptibility was done by disk diffusion and agar dilution methods for determining the Minimum Inhibitory Concentration (MIC). The detection of mutation in Quinolone Resistance Determinant Region (QRDR) in gyrA gene was done by sequencing. Campylobacter was isolated from 100% of the samples, being 68.75% C jejuni and 31.25% C co/i. By the disk diffusion method, resistance to ciprofloxacin was observed in all isolates and 56.25% of the strains were resistant to enrofloxacin. By agar dilution method, all strains were resistant to ciprofloxacin (MIC >= 16 mu g/mL to >= 64 mu g/mL) and full and intermediate resistance to enrofloxacin was detected in 42.50% (MIC >= 4-32 mu g/mL) and 38.75% (MIC =2 mu g/mL) of the strains, respectively. Mutation Thr-86-1Ie was observed in 100% of the isolates investigated. In addition to this mutation, others no silent mutations (Val-73-Glu, Ser-114-Leu, Val-BB-Asp, Ala-75Asp, Gly-119-Ser, Arg-79-Lys) and silent mutations (His-81- His, Ser-119-Ser, Ala-120-Ala, Phe-99-Phe, Ala-122-Ala, Gly-74-Gly, Ile-77-Ile, Ala-91-Ala, Leu-92-Leu, Val-93-Val, Ile-106lie, Thr-107-Thr, Gly-113-Gly, Ile-115-Ile, Gly-110-Gly) were detected. All the enrofloxacin-sensitive strains by the phenotypic methods had the 'Thr-86 to Ile substitution, which suggests other mechanisms contributing to enrofloxacin resistance in Campylobacter.