Control of the contamination of pig carcasses by Escherichia coli from their mouths

Abstract

Swab samples from the mouths of 40 pig carcasses all yielded Escherichia coli, at estimated log mean numbers of 2.3 per sample. Single colonies of E. coli O157:H7 were isolated from two, and single colonies of other verotoxigenic strains of E. coli from a further two of those samples. E. coli from the mouth were deposited on the surfaces of carcasses during usual, commercial carcass dressing operations for cutting open the throat and the floor of the mouth, and freeing the tongue. After those operations had been performed, E. coli were recovered from a neck site on 45 of 50 carcasses which were sampled by swabbing that site. When 50 carcasses on which those operations had been performed were pasteurized, the log mean numbers of total aerobic counts recovered from the neck site on carcasses were reduced by two as compared with the unpasteurized carcasses, and only one E. coli was recovered from those carcasses. Pasteurization bleached the small areas of cut muscle exposed during the operations on the mouth and throat, but apparently had no other effect on the appearance of the carcasses. It is suggested that pasteurization of pig carcasses after operating 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.