Prevalence, Antimicrobial Resistance, and Molecular Characterization of Campylobacter Isolated from Broilers and Broiler Meat Raised without Antibiotics

Campylobacter is one of the main bacterial pathogens that cause campylobacteriosis in the United States. Poultry is considered a major reservoir for the transmission of Campylobacter to humans. This study aimed to determine the prevalence and molecular characteristics of Campylobacter in the no-antibiotics-ever (NAE) broilers. A total of 414 samples were collected, among which 160 retail chicken samples were purchased from grocery stores and 254 samples were collected from broiler farms located in Mississippi State. The overall prevalence of Campylobacter was 25.4%, and a significantly higher prevalence was observed in retail chicken than in the farm samples (36.3% versus 18.5%; P  <  0.0001), respectively. The prevalence of Campylobacter was not different (P  =  0.263) between conventional retail (40.0%) and NAE (31.4%) retail chicken. Campylobacter jejuni was the predominant species among the positive isolates, accounting for 78.1%. Among the 82 C. jejuni isolates, 52.4% of the isolates carried the gyrA gene followed by the tet(O) gene (14.6%), whereas toxin-producing genes cdtA, cdtB, and cdtC were carried by 43.9%, 46.3%, and 43.9%, respectively. However, none of these virulence genes were detected in C. jejuni isolated from litter samples. Among tested C. jejuni, 13.6% of the isolates were multidrug resistant. The highest resistance was observed against nalidixic acid (49.2%), followed by tetracycline (23.7%). Our study suggests that the prevalence of Campylobacter was higher in retail meat samples than in environmental samples obtained from farms, and there was no difference in Campylobacter prevalence among conventional and NAE retail chicken.