Reduction of Yersinia enterocolitica and Listeria spp. on pig carcasses by enclosure of the rectum during slaughter.

By sealing off the rectum with a plastic bag immediately after it had been freed, the spread of Y. enterocolitica O:3/biovar 4 to pig carcasses could be considerably reduced. The organism was recovered from only 0.8% of carcasses when the plastic bag technique was employed. Y. enterocolitica O:3/biovar 4 was recovered from 10% of pig carcasses when eviscerating procedures did not include the use of the plastic bag technique. There was thus an obvious risk of the bacteria further contaminating meat cuts and other meat products. The plastic bag technique was effective both in connection with manual excision of the rectum/low throughput (90 per h), and mechanical freeing of the rectum/high slaughter rate (240 per h). L. monocytogenes was not detected in any of the samples taken from 120 pig carcasses in Norway or from 120 pig carcasses in Sweden. The plastic bag technique was used on half of these pigs. L. innocua was tested for in 120 pigs slaughtered in Sweden. The bacterium was recovered from 33% of the carcasses eviscerated without using a plastic bag, and from 10% of the carcasses in which this technique was employed. The results suggested that there were other, non-faecal, sources of contamination. Other measures in addition to the plastic bag technique are therefore required to limit the spread of Listeria spp. By incorporating the plastic bag technique into the slaughtering procedures, the meat industry would contribute to preventing the dissemination of Y. enterocolitica and other pathogens which spread via the faeces.