Antimicrobial Resistance and Genomic Characteristics of Campylobacter spp. from Australian Meat Chickens

The increasing resistance of bacteria to antimicrobials is a major threat to public health. This study focuses on the antimicrobial resistance (AMR) profiles and genetic relationships of Campylobacter jejuni and Campylobacter coli. Isolates (n = 186) were obtained at slaughter from 200 pooled cecal samples taken from 1,000 meat chickens. Majority of C. jejuni (68.7%) and C. coli (88.9%) isolates were susceptible to all antimicrobials and no multi-drug resistance was found. Resistance to ciprofloxacin (fluoroquinolone) was detected in 24.4% of the C. jejuni and 3.2% of the C. coli isolates. Whole genome sequencing revealed a diverse range of sequence types (STs). These included 32 previously reported STs for C. jejuni and 13 for C. coli, as well as four and seven previously undescribed STs for each species, respectively. The STs containing fluoroquinolone-resistant isolates were ST2083, ST10130, ST2895, ST7323, ST2398, and ST1078 for C. jejuni, and ST860 and ST894 for C. coli. Although fluoroquinolones are not used in animal production in Australia, resistance amongst C. jejuni isolates was high (24.4%). This finding emphasizes the need for enhanced surveillance and sampling along the food chain to understand the source of the isolates and to mitigate risks of AMR to protect public health.