OCCURRENCE OF LISTERIA AND YERSINIA SPECIES IN MILK AND SOME MILK PRODUCTS

Two hundred raw milk and dairy product samples (50 cow’s milk and 25 each of sheep’s milk, goat’s milk, pasteurized milk, white soft cheese, plain yoghurt and fruit yoghurt) were collected from dairy farms and different localities, markets and shops in El Dakahlia Province, Egypt and examined for the presence of Listeria and Yersinia species as food poisoning and mastitis causing organisms. The incidence of Listeria spp. in raw milk and dairy product samples was 3.0% and their distributions were 6.0% in cow's milk, 8.0% in goat's milk, 4.0% in white soft cheese samples and can't be detected in sheep's milk, pasteurized milk and both fruit and plain yoghurt samples. The incidence of Listeria monocytogens in raw milk and dairy product samples was 3 (1.5%), the other Listeria spp. were L. innocua 5 (2.5 %) and L. welshimeri 2 (1.0%). Yersinia spp. could be isolated from 41 (20.5 %) of examined raw milk and dairy product samples. The incidence percentages were 40.0% in cow's milk, 20.0% in sheep's milk, 32.0% in goat's milk, 4.0% in pasteurized milk, 8.0% in white soft cheese, 12.0% in fruit yoghurt and 8.0% in plain yoghurt. Yersinia enterocolitica, Yersinia intermedia, Yersinia kristensenii, Yersinia frederiksenii and Yersinia pseudotuberculosis could be detected in (5, 1, 2, 0, 1, 1 and 1); (10, 2, 0, 1, 2, 0 and 0); (3, 0, 0, 0, 0, 1 and 1); (0, 3, 4, 0, 0, 0 and 1) and (4, 0, 4, 0, 0, 2 and 0) of examined samples, respectively. The sanitary and public health importance of these organisms as well as control measures to improve the quality of dairy products and to safeguard the consumers from infection were discussed.