Occurrence, antimicrobial resistance and virulence properties of thermophilic Campylobacter coli originating from two different poultry settings

Thermophilic Campylobacter's (Campylobacter coli and Campylobacter jejuni) are usually zoonotic and spread by raw or undercooked meat especially poultry meat, unpasteurized milk, direct animal contact, and contaminated drinking water. In this study, 385 samples from commercial and backyard poultry settings were screened for the presence of Campylobacter spp. which revealed an isolation rate of 3.9% with higher isolation from the chicken caecum (15/113, 13.27%). On antimicrobial susceptibility testing, the highest resistance was observed for tetracycline (11/13, 84.61%) followed by macrolides (8/13, 61.53%), beta-lactams (7/13, 53.84%), fluoroquinolones (5/13, 38.45%) and sulphonamide (4/13, 30.76%). Isolates from backyard poultry showed resistance to tetracycline (100%), beta-lactam (66.66%), fluoroquinolone (25%), and macrolide (33.33%). Isolates from commercial poultry showed resistance to tetracycline (80%), macrolides (70%), beta-lactams (51.66%), fluoroquinolones (42.5%) and sulphonamides (40%). Among the isolates, 92.30% were multi-drug resistant (MDR). Overall, tet(O) gene was observed in 6/11(54.55%) tetracycline resistant isolates. Notably, tet O gene was found in 6/8(75%) isolates from commercial poultry farms and it was absent in backyard poultry isolates. Similarly 23SrRNA and blaOXA-61 genes were detected in 4/8(50%) and 2/8(25%) macrolide and ampicillin resistant isolates, respectively. Among virulence genes, cdtC gene was noticed in all the Campylobacter isolates (100%), cadF in 93.33%, iamA in 80%, flaA in 73.33%, cdtA in 13.33% and, cdtB in 6.66% isolates while dnaJ, ciaB and pldA genes were not detected in any of the isolate. The Campylobacter isolates possessing antimicrobial resistance and virulence genes pose a serious public health threat through food chain.