Prevalence and Biomolecular Characterization of Campylobacter spp. Isolated from Retail Meat

Abstract

We estimated the prevalence of Campylobacter spp. in retail meat (n = 352 samples; 104 chicken, 106 pork, and 142 beef) collected in Campobasso, Italy, comparing two microbiological methods. All the isolates were characterized by biomolecular techniques for epidemiological purposes. Campylobacter isolation was performed by selective culture and membrane filtration methods. Phenotypic and genotypic methods for genus and species identification were evaluated together with antimicrobial resistance and plasmid profiling. Sixty-nine (86.2%) samples were positive by selective culture, 49 (61.2%) by membrane filtration, and 38 (47.5%) by both methods. Only 74 of 80 strains were confirmed as Campylobacter spp. by PCR, and two Campylobacter coli were identified as Campylobacter jejuni . Chicken meat was more frequently contaminated than other meats. Selective culture was more sensitive than membrane filtration (85 versus 66%), and specificity of the methods was 98 and 100%, respectively. Among Campylobacter isolates from chicken meat, 86.5% were multidrug resistant. Resistance to ciprofloxacin (51.3%) and enrofloxacin (52.7%) was lower than to nalidixic acid (71.6%). C. coli strains showed the highest cross-resistance for quinolones (82.6%) and fluoroquinolones (60.9%) as well as a high resistance to tetracycline. Plasmids were isolated from six C. coli and two C. jejuni isolates, but no association was detected between antimicrobial resistance and plasmid DNA carriage. Selective culture is considered as the optimal method for Campylobacter isolation, although it was unable to detect all contaminated samples. Membrane filtration provided more specific results but with low sensitivity. A combination of both techniques may offer better results.