Characterization of Antimicrobial Resistance in <i>Campylobacter</i> Species from Broiler Chicken Litter

Campylobacteriosis in human populations has been an ongoing issue in both developed and developing countries over the last 10 years. There is a grave concern whether poultry production plays an intermediate role as a reservoir and source of transmission. In this study, sixty-five broiler chicken Campylobacter isolates were isolated from fecal samples collected from 17 flocks in Alberta, Canada over two years (2015-2016). Campylobacter jejuni was the predominantly recovered Campylobacter species in both years. Approximately 33% (8/24) Campylobacter coli was identified in year 2016. The two most common antimicrobial resistance patterns in Campylobacter in year 2015 were tetracycline resistance (39%) and azithromycin/clindamycin/erythromycin/telithromycin resistance (29%). Only one isolate in 2015 displayed resistance to ciprofloxacin/nalidixic acid/tetracycline. The tetO gene was detected in all tetracycline resistant isolates in 2015. The cmeB gene was detected in all isolates with resistance to azithromycin/clindamycin/erythromycin/ telithromycin, and two isolates with resistance to tetracycline. Comparing the sequence of the cmeB genes from isolates with different resistance patterns revealed several single nucleotide polymorphisms. Transconjugants with three distinctly combined resistance patterns were obtained via in vitro conjugation. In conclusion, our study suggested that poultry can be a potential reservoir for and source of transmission of Campylobacter for human infection and requires an ongoing monitoring.