Isolation, Antimicrobial Resistance, and Virulence Genes of Thermophilic Campylobacter Species from Backyard Ducks in Amol, Northern Iran

Domestic poultry are considered natural reservoirs for the transmission of Campylobacter spp., mainly C. jejuni and C. coli, to other birds and humans. This study aimed to determine the Campylobacter infection status in backyard ducks in Iran. A total of 100 cloacal swabs were obtained from apparently healthy backyard ducks in different rural areas of Amol, a city in northern Iran. Bacterial isolation was based on traditional culture procedures, and genus and species identification were performed using an mPCR. All isolates were examined for antimicrobial resistance to seven antibiotics by Kirby Bauer’s disk diffusion test. The virulence-associated genes cadF, iamA, pldA, cdtA, cdtB, cdtC, and wlaN were detected as well. Out of the 27 Campylobacter isolates recovered, 19 (70.4%) were C. coli, and 3 (11.1%) were C. jejuni. The remaining five isolates (18.5%) were not identified. All (100%) isolates showed resistance to ciprofloxacin. Most isolates were resistant to ampicillin, tetracycline, and nalidixic acid. The resistance rate to amoxicillin-clavulanic acid and erythromycin was moderate but was relatively low to gentamicin. Moreover, over two-thirds of the isolates were MDR. All virulence genes, except iamA, were variably detected. The cadF and pldA genes had the highest (92.6%) and lowest (7.4%) positivity rates, respectively. In addition, a statistically significant association was observed between Campylobacter spp. and most of the critical virulence genes (p < 0.05). Our findings imply that backyard ducks should be paid attention to as a major source of human campylobacteriosis.