Survey of Campylobacter jejuni in retail chicken meat products by application of a quantitative PCR protocol

Campylobacter-contaminated food products are currently the cause of the highest number of gastroenteritis cases in developed countries. Apart for biosafety measures at the primary production level, no other official control measures are currently in place for its control. This is partly due to the lack of quantitative data regarding the prevalence and contamination level of different food products by Campylobacter spp. that does not allow for quantitative risk assessment. PCR-based methods, applied without prior enrichment, in food samples circumvent limitations associated with the quantification of foodborne pathogens by traditional, culture-dependent methods. In this study, we report the development of a protocol, based on the amplification of the rpoB gene of Campylobacter jejuni, by quantitative PCR (qPCR), directly in food samples. The quantification limit of the protocol was determined to be in the order of 10 colony forming units (cfu)/g or ml of food sample. The optimized protocol was applied for the survey of C. jejuni in naturally contaminated poultry samples. In parallel, traditional sampling was also performed. A high percentage of samples (87%) resulted to be positive by qPCR, while no C. jejuni was detected by traditional analysis. Furthermore, important differences were observed in the detection by qPCR between samples before and after enrichment.