Rapid identification and quantification of Campylobacter coli and Campylobacter jejuni by real-time PCR in pure cultures and in complex samples

With a sensitivity of 10 genome copies and a linear range of seven to eight orders of magnitude, the C. coli and C. jejuni real-time PCR assays allowed a precise quantification of purified DNA from C. coli and C. jejuni. The assays were highly specific and showed a 6-log-linear dynamic range of quantification with a quantitative detection limit of approximately 2.5 × 102 CFU/g of faeces, 1.3 × 102 CFU/g of feed, and 1.0 × 103 CFU/m2 for the environmental samples. Compared to the results obtained by culture, both C. coli and C. jejuni real-time PCR assays exhibited a specificity of 96.2% with a kappa of 0.94 and 0.89 respectively. For faecal samples of experimentally infected pigs, the coefficients of correlation between the C. coli or C. jejuni real-time PCR assay and culture enumeration were R2 = 0.90 and R2 = 0.93 respectively.The C. coli and C. jejuni real-time quantitative PCR assays developed in this study provide a method capable of directly detecting and quantifying C. coli and C. jejuni in faeces, feed, and environmental samples. These assays represent a new diagnostic tool for studying the epidemiology of Campylobacter by, for instance, investigating the carriage and excretion of C. coli and C. jejuni by pigs from conventional herds.Campylobacter spp. are recognized as the leading human foodborne pathogens in developed countries [1,2]. Within the genus Campylobacter, the thermophilic species Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) are the most frequently associated with illness, accounting for over 95% of infections (respectively responsible for 80 to 85% and 10 to 15%) [2]. These two species commonly live in the intestinal tract of birds and mammals, including food production animals and pets, without causing clinical signs [3]. Livestock animals carrying Campylobacter pose an important risk for human infection from contamination of carcasses at slaughter, of milk, and water contaminated by livestock wastes and slurries [4-6]. Res