The effects of preslaughter washing on the reduction of Escherichia coli O157 : H7 transfer from cattle hides to carcasses during slaughter

Fresh bovine faeces were inoculated with a non-toxigenic, antibiotic resist ant strain of Escherichia coli O157:H7, spread on the rump areas of 30 heif ers and allowed to dry for 24 h. Ten of the cattle then entered the normal slaughter process without further treatment. The remaining cattle were wash ed with a powerhose for 1 min (10 animals) and 3 min (10 animals) before en tering the normal slaughter process. Both washing treatments removed all vi sible faecal materials on the live animals although a significant reduction (P < 0.05) in E. coli O157:H7 levels on the hides was only observed on tho se animals which were powerhosed for 3 min. After slaughter, E. coli O157:H 7 was detected on carcasses and on the knives and hands of operatives. Pres laughter washing for 3 min did not statistically reduce the numbers of E. L oll O157:H7 transferred from the hide to the carcass during slaughter. Howe ver, the organism was not detected on three of the four areas of the carcas s sampled, indicating that washing may be a suitable method of decontaminat ion animal hides before slaughter and as such deserves further investigatio n.