Quantification of hygiene indicators and Salmonella in the tonsils, oral cavity and rectal content samples of pigs during slaughter.

The tonsils, oral cavity and faeces of 94 pigs at slaughter were sampled to assess the numbers of total aerobic bacteria, Enterobacteriaceae and Escherichia coli in the rectal content, tonsils and oral cavity of pigs at time of evisceration. Moreover, the prevalence, numbers and types of Salmonella spp. were determined. Mean numbers of Enterobacteriaceae in tonsils and the oral cavity differed between slaughterhouses. The proportion of Enterobacteriaceae relative to total aerobic bacteria differed between the different tissues, though large variations were observed between animals. Salmonella spp. were mostly detected in oral cavity swabs (n = 51, 54%), of which six samples were contaminated in numbers over 2.0 log CFU/100 cm2. Salmonella spp. were also recovered from 17 tonsillar tissue samples (18%) and 12 tonsillar swabs (13%). Out of the 29 rectal content samples from which Salmonella was recovered (31%), most were lowly contaminated, in the range between -1 and 0 log CFU/g. The predominant serotypes were S. Typhimurium and its monophasic variant, which were recovered from 33 and 13 pigs, respectively. In most cases, the same serotypes and MLVA profiles were found in pigs slaughtered during the same day, thus suggesting a common source of contamination.