Detection of fluoroquinolone resistance by mutation in gyrA gene of Campylobacter spp. isolates from broiler and laying poedeiras, no Estado do Rio de Janeiro, Brasil

Poultry are considered to be the main reservoir of Campylobacter spp. bacteria, an important pathogen for humans. Many studies have reported a rapid selection of fluoroquinolone-resistant strains following the widespread use of these antimicrobials in poultry production and human medicine. The main mechanism of fluoroquinolone resistance in Campylobacter is a mutation in the Quinolone Resistance Determinant Region (QRDR) in the gyrA gene, which codes for the subunit of the enzyme DNA gyrase, the target for fluoroquinolone. The aim of this study was to investigate the mutation in QRDR in the gyrA gene of Campylobacter strains previously isolated from broiler carcasses and feces of laying hens. Thirty-eight strains of C. jejuni and 19 C. coli strains (n=57), previously characterized as resistant to ciprofloxacin and enrofloxacin by the disk diffusion method and minimum inhibitory concentration (MIC), were selected. For detection of the mutation, a fragment of 454pb QRDR in the gyrA gene was used for direct sequencing. All strains presented the QRDR mutation in the gyrA gene at codon 86 (Thr86-Ile), which confers resistance to fluoroquinolones. Other known silent mutations were observed. This genotypic characterization of fluoroquinolone resistance in Campylobacter strains has confirmed the prior phenotypic detection of the resistance. The Thr-86-Ile mutation was observed in all samples confirming that this is the predominant mutation in enrofloxacin and ciprofloxacin resistant strains of C. jejuni and C. coli. Key words: enrofloxacin, ciprofloxacin, poultry C. jejuni, C. coli. As aves sao consideradas o principal reservatorio de Campylobacter spp., um importante patogeno para humanos e muitos estudos tem relatado uma rapida selecao de cepas resistentes as fluoroquinolonas apos o uso destes antimicrobianos na producao avicola e na medicina humana. O principal mecanismo de resistencia as fluoroquinolonas em Campylobacter consiste na mutacao na Regiao Determinantes de Resistencia as Quinolonas (RDRQ) do gene gyrA, que codifica para a subunidade A da enzima DNA girase, alvo das fluoroquinolonas. O objetivo deste estudo foi investigar a mutacao na RDRQ do gene gyrA em cepas de Campylobacter previamente isolados de carcacas de frangos de corte efezes de galinhaspoedeiras.Foram selecionadas 38 cepas de C. jejuni e 19 cepas de C. coli (n=57), previamente caracterizadas como resistentes a ciprofloxacina e enrofloxacina, pelo metodo da difusao em disco e pela determin