Detection of low numbers of pathogenic Yersinia enterocolitica in environmental water and sewage samples by nested polymerase chain reaction

Isolation of pathogenic Yersinia enterocolitica from water and sewage bg tr aditional culture techniques is time-consuming and subsequent differentiati on between pathogenic and non-pathogenic strains can be difficult and unrel iable. A nested polymerase chain reaction (PCR) procedure was used for the detection of low numbers of Y. enterocolitica in spiked samples fi om natur al surface sources with variable background flora ranging from oligotrophic water to sewage. Water and sewage samples were filtered and filters enrich ed overnight in a non-selective medium. Nested PCR conducted on enriched br oth, prepared by use of a rapid and simple preparation step consisting of c entrifugation, proteinase K treatment and boiling, enabled the detection of 8-17 cfu 100 ml(-1) water with background levels of up to 8700 heterotroph ic organisms ml(-1) and 10 000 cfu coliform organisms 100 ml(-1) water. The analysis can be completed within 2-3 d and should be a significant tool in monitoring environmental waters and drinking water sources for the presenc e of pathogenic Y. enterocolitica.