ARS | Publication request: THE CANNULATED PIG: A MODEL FOR MONITORING THE DYNAMICS OF FOODBORNE PATHOGENS IN VIVO

Submitted to: Pig Veterinary Society International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 20, 2000
Publication Date: N/A

Technical Abstract: The goal of this study was to monitor the dynamics of Salmonella typhimurium and Y. enterocolitica in the pig intestine. Specific objectives were: (a) to compare the in vitro growth of S. typhimurium and Y. enterocolitica in varying concentrations of VFA and pH to simulate the caecal environment of a regularly-fed and fasted pig; (b) to develop a protocol to surgically cannulate pigs which would permit normal activity to retain intestinal motility; and (3) to monitor the dynamics of S. typhimurium and Y. enterocolitica in regularly fed and fasted surgically cannulated pigs. The growth of S. typhimurium in five VFA concentrations (0, 25, 50, 75, and 100 mM) at four pH values (6.0, 6.5, 7.0, and 7.5) was measured spectrophotometrically (650 nm). Maximal growth was achieved in the absence of VFA (0 mm); minimal growth, at 100 mM VA. Likewise, for Y. enterocolitica maximum growth occurred at 0 mM VFA, pH 5.6. VFA (> 25 mM) at any pH inhibited growth. In fasted pigs, VFA concentrations declined resulting in pH increases. Salmonella and Yersinia when instilled into surgically cannulated pigs colonized the caeca and could be detected for up to ~3 weeks. However, no predictable alterations in the levels of Salmonella or Yersinia in either the caecal fluid or feces occurred when the feeding regimen was altered. The pig caecal model is ideal for studying the dynamics of foodborne pathogens in vivo. It offers access to intestinal tract sampling and indicates that monitoring the caecal population may be a more reliable gauge of foodborne pathogen kinetics following dietary changes than fecal sampling.