Contamination of Pig Carcasses with Escherichia coli from their Mouths

C.O. Gill and T. Jones

Agriculture and Agri-Food Canada Research Centre, 6000 C & E Trail, Lacombe, AB, Canada T4L 1W1

Swab samples from the mouths of 40 pig carcasses all yielded Escherichia coli, at mean numbers of about 200 cfu/swab. Single colonies of E. coli 0157:H7 or other verotoxigenic strains of E. coli were isolated from four of those samples. E. coli from the mouths were deposited on the surfaces of carcasses during a usual, commercial carcass dressing operation for cutting open the throat and the floor of the mouth, and freeing the tongue. After that operation, a total of about 400 E. coli was recovered from swabs of a neck site on each of 50 carcasses. When 50 carcasses on which that operation had been performed were pasteurized, the total numbers of total aerobic, coliform and E. coli counts recovered from the neck site were reduced by two orders of magnitude as compared with the unpasteurized carcasses. Pasteurization bleached the small areas of cut muscle exposed by operation on the mouth and throat, but apparently has no other effect on the appearances of carcasses. It is appears that pasteurization of pig carcasses after operation on and regulatory inspection of the mouth and throat may be a commercially viable approach to reducing the contamination of pork with pathogens from the mouths of carcasses.