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

Abstract

<i>Campylobacter</i> is one of the main bacterial pathogens that cause campylobacteriosis in the United States. Poultry is considered a major reservoir for the transmission of <i>Campylobacter</i> to humans. This study aimed to determine the prevalence and molecular characteristics of <i>Campylobacter</i> 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 <i>Campylobacter</i> was 25.4%, and a significantly higher prevalence was observed in retail chicken than in the farm samples (36.3% versus 18.5%; <i>P < </i>0.0001), respectively. The prevalence of <i>Campylobacter</i> was not different (<i>P = </i>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 <i>gyrA</i> gene followed by the <i>tet</i>(O) gene (14.6%), whereas toxin-producing genes <i>cdtA</i>, <i>cdtB</i>, and <i>cdtC</i> 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 <i>Campylobacter</i> was higher in retail meat samples than in environmental samples obtained from farms, and there was no difference in <i>Campylobacter</i> prevalence among conventional and NAE retail chicken. <b>IMPORTANCE</b> The FDA antibiotic withdrawal policy has led to a shift in the production system, from conventional antibiotics fed birds to no antibiotics ever (NAE) raised birds. However, the impact of this shift to NAE on the prevalence and characteristics of <i>Campylobacter</i> has not been studied on the farm or in retail chicken meats. The objective of this study was to determine the current prevalence of <i>Campylobacter</i> and the distribution of their antimicrobial resistance and virulence genes in NAE-raised broilers. The findings of this study will help the industry to take necessary action to develop effective mitigation strategies for reducing <i>Campylobacter</i> contamination in NAE broilers.