Verocytotoxin-producing Escherichia coli O157 in minced beef and dairy products in Italy

A total of 3879 samples of foodstuffs were examined for the presence of Verocytotoxin-producing Escherichia coli O157 (VTEC O157). The survey was conducted by 9 of the 10 Italian Veterinary Public Health Laboratories. Samples were collected between May 2000 and September 2001 in 14 regions and comprised 931 minced beef specimens and 2948 dairy products (DP) with less than 60 days of ripening. The DP included 657 pasteurised and 811 unpasteurised bovine DP, 477 pasteurised and 502 unpasteurised ovine DP, and 501 water-buffalo's milk mozzarella cheese. Samples were collected at retail level, from plants processing minced beef and dairy plants and from farms directly manufacturing cheeses. All the samples were tested using a sensitive procedure based on ISO/DIS 16654:1999 (later ISO 16654:2001), which includes an immunomagnetic separation step. A preliminary inter-laboratory trial was organised with artificially contaminated samples to assess the ability of all the participating laboratories to isolate E. coli O157 by the established procedure. VTEC O157 was isolated from four (0.43%) of the minced beef samples, collected in four different regions and during different months, but was not detected in any of the dairy products. E. coli O157 VT-eae+ was isolated from one raw cow's milk cheese. This survey provided national data on the presence of VTEC O157 in foodstuffs, demonstrating a low prevalence of the organism. The survey also encouraged updating of knowledge and procedures on VTEC O157 in laboratories with official responsibility for microbiological testing of foods of animal origin.