The potential use of chilling to control the growth of Enterobacteriaceae on porcine carcasses and the incidence of E-coli O157:H7 in pigs

To (i) monitor the presence of Enterobacteriaceae as indicators of faecal contamination on pig carcasses, (ii) examine the potential use of chilling as a critical control point (CCP) and establish its influence on pig carcass categorization by Decision 471/EC and (iii) determine the incidence of E. coli O157:H7 in pigs. Porcine faecal samples and carcass swabs were collected before and after chilling at four Irish pig abattoirs and examined for Enterobacteriaceae and E. coli O157:H7. Chilling generally reduced Enterobacteriaceae counts on carcasses, but increases were also observed, particularly in one abattoir. E. coli O157:H7 was absent from carcasses before chilling, present on 0.21% after chilling and was recovered from 0.63% of faecal samples. All of the isolates were found to contain virulence genes associated with clinical illness in humans. The data show that overall chilling had the capacity to reduce the numbers of carcasses positive for the presence of Enterobacteriaceae. The influence of chilling on the categorization of pig carcasses suggests that it has the potential to improve the numbers of acceptable carcasses and the process could be used as a CCP within a HACCP plan.