Prevalence of Salmonella spp. and Yersinia enterocolitica in/on tonsils and mandibular lymph nodes of slaughtered pigs.

A total of 156 tonsils and 156 mandibular lymph nodes from fattening pigs originating from 13 farms were sampled in Croatian slaughterhouses and examined for Salmonella spp. (n=78 per organ) and Yersinia enterocolitica (n=78 per organ) by cultural methods. Salmonella was isolated from two tonsils only, both originated from animals from the same farm (5.12%), while Y. enterocolitica were recovered from 26 tonsils (33.33%) which could be traced back to 10 farms. Salmonella was absent in mandibular lymph nodes, and Y. enterocolitica was isolated from eight lymph nodes (10.25%) which originated from six farms. Y. enterocolitica was present inside the lymph nodes of two pigs. The high prevalence of Y. enterocolitica in/on pig tonsils could be the result of cross-contamination during splitting the carcasses with head. This procedure may result in higher prevalence of Y. enterocolitica on surface of mandibular lymph nodes than in their depth. Traditional veterinary postmortem examination of pig halves will not necessarily contribute to cross-contamination with Salmonella or Yersinia under conditions of present slaughter practice.