Prevalence and concentration of verocytotoxigenic Escherichia coli, Salmonella enterica and Listeria monocytogenes in the beef production chain: a review.

This review examines the prevalence of three important pathogens, verocytotoxigenic Escherichia coli (VTEC), Salmonella enterica and Listeria monocytogenes, in cattle and beef from the farm to the final, ready-to-eat product. Factors affecting prevalence of pathogens in the beef chain, such as the season and cattle rearing method, are examined. Data from many key surveys are summarized in table form. The observed prevalence of pathogens in cattle and beef varies considerably from survey to survey. An indication of relative prevalence of pathogens at different stages can be obtained by calculating average prevalences observed over multiple surveys, weighted by sample number. Based on the data presented in the tables in this review, for E. coli O157 at selected processing stages the mean prevalences (and range of means from individual surveys) are faeces 6.2% (0.0-57%), hides 44% (7.3-76%), chilled carcasses 0.3% (0.0-0.5%), and raw beef products 1.2% (0.0-17%). For Salmonella the mean prevalence data are faeces 2.9% (0.0-5.5%), hides 60% (15-71%), chilled carcasses 1.3% (0.2-6.0%), and raw beef products 3.8% (0.0-7.5%). For L. monocytogenes the mean prevalence data are faeces 19% (4.8-29%), hides 12% (10-13%), and raw beef products 10% (1.6-24%). Seasonal variation was evident in many surveys, faecal prevalences of E. coli O157 and Salmonella generally being higher in the warmer months. The influence of animal type, animal age, feed and housing on pathogen carriage has also been examined. The significance of non-O157 serotypes of VTEC and their detection and classification are discussed.