Optimization of PCR-based methods for rapid detection of Campylobacter jejuni, Campylobacter coli and Yersinia enterocolitica serovar 0:3 in wastewater samples

Abstract

PCR-based methods were evaluated for their adequacy to assess the removal of pathogens from wastewater samples. For the development and optimization of the methods, samples were taken at two different sites from two different constructed wetlands. Campylobacter jejuni/coli and Yersinia enterocolitica serogroup 0:3 were selected as model pathogens and Enterococcus faecalis as a standard microbiological indicator. The chosen PCR protocols were optimized for wastewater DNA extracts in order to obtain high sensitivity and reproducibility independently of the background flora. All PCR protocols were successfully performed and reproducible with a background of up to 10(10) nontarget cells per reaction. Five cells of Y. enterocolitica, 50 cells of C. jejuni/coli, and 500 cells of E. faecalis per 100ml treated water could be detected. The method detection limit in the settled wastewater was higher: 200 cells per 100ml for Y. enterocolitica, 2000 cells per 100ml for C. jejuni/coli, and 20,000 cells per 100ml for E. faecalis. C. jejuni/coli and Y. enterocolitica PCRs were adapted to municipal wastewater, with higher loads of potential PCR inhibitors. Sensitivity was lower for this type of wastewater: 200 cells of Y. enterocolitica and 2000 cells of C. jejuni/coli were detected per 100ml treated wastewater, 2500 cells of Y. enterocolitica and 25,000 cells of C. jejuni/coli per 100ml settled wastewater. The developed PCR methods enable the detection of C. jejuni/coli, Y. enterocolitica serogroup 0:3 and E. faecalis within 12h. They show specificity, reproducibility and low detection limits for the investigated pathogens.