Phenotypic and Genotypic Characterization of Antimicrobial Resistance in Thermophilic Campylobacter Species Isolated From Faecal Samples of Chicken and Turkey

Background: Thermophilic Campylobacter species cause significant economic losses in cases of enteritis in poultry. Objective: The aim of this study was to isolate and identify Campylobacter jejuni, Campylobacter coli and Campylobacter lari from chicken and turkey faeces samples using bacteriological and molecular methods. Also, to determine the antibiotic susceptibilities and antibiotic resistance genes of the isolates. Materials and methods: Within the scope of the study, 201 cloacal swab samples were collected from 132 chickens and 69 turkeys. Phenotypic and genotypic examinations were performed on the isolates obtained for resistance to various antimicrobial agents. Results: Campylobacter spp. was isolated from 38.30% of the samples. PCR (polymerase chain reaction) analysis identified 63.63% of the isolates as C. jejuni and 23.37% as C. coli. The highest resistance rates of the isolates were determined against cephalothin (81.81%), nalidixic acid (72.72%) and aztreonam (61.03%). Multidrug resistance was found in 50% of Campylobacter spp. strains. The highest susceptibility in C. jejuni and C. coli strains was observed against gentamicin (95.91% and 100%). Statistical analyses demonstrated no significant differences between C. jejuni and C. coli with respect to most of the antibiotics tested (p > 0.05). However, a statistically significant difference was observed for nalidixic acid (p = 0.009). The bla(OXA-61) gene tested positive in 79.71% of the phenotypically ampicillin-resistant isolates. The tet(O) gene was identified in 72.2% of tetracycline-resistant isolates and the aphA-3-1 gene in 5.8% of aminoglycoside-resistant isolates. The ERY2074 and ERY2075 genes were identified in 50% and 78.57% of the 28 isolates with erythromycin resistance genes, respectively. The cmeA, cmeB and cmeC genes were identified in 51.28%, 79.48% and 25.6% of the strains that developed multidrug resistance, respectively. The Thr-86-Ile point mutation was found in 92% of the isolates that carried the gyrA gene responsible for quinolone resistance. Conclusion: The high susceptibility of the isolates to gentamicin in vitro suggests that gentamicin could be a potential agent for limiting Campylobacter colonization in poultry.