Qualitative and Quantitative Detection of Human Pathogenic Yersinia enterocolitica in Different Food Matrices at Retail Level in Bavaria

Abstract

Yersinia enterocolitica is a major foodborne pathogen and the third most important bacteriological cause of diarrhea in Germany. However, studies investigating the occurrence of human pathogenic Y. enterocolitica in food at the retail level are very rare. Most of the studies published so far show qualitative but not quantitative data concerning the prevalence of this human pathogen. In this study the qualitative and quantitative assessment of human pathogenic Y. enterocolitica in different food matrices was investigated. For the qualitative analysis we used an enrichment method according to the International Organisation of Standardization (ISO) standard in combination with a real-time polymerase chain reaction (PCR) method detecting the ail gene of Y. enterocolitica. After detecting Y. enterocolitica in a sample, a quantitative investigation on Cefsulodin-Irgasan-Novobiocin (CIN) Agar was done to get information about the contamination level of the different samples. During the years 2008 and 2009, 446 samples of pork and pork products, 51 samples of game meat, and 61 raw milk samples were investigated for the presence of human pathogenic Y. enterocolitica. The samples were collected at the retail level in Bavaria. From the pork samples investigated, 81 samples (18%) were positive for the ail gene by real-time PCR, but human pathogenic Y. enterocolitica O:3 were found only in 46 (10%) pork samples by culture; the concentration in the samples ranged between 0.04 cfu/g and 2.30 × 10⁵ cfu/g. Three game meat samples were positive by real-time PCR, but not by the cultural detection. All raw milk samples were negative by real-time PCR and culture.