A rat model for dose-response relationships of Salmonella Enteritidis infection

Aims: To develop an animal model to study dose-response relationships of en teropathogenic bacteria. Methods and Results: Adult, male Wistar Unilever rats were exposed orally t o different doses of Salmonella enterica serovar Enteritidis after overnigh t starvation and neutralization of gastric acid by sodium bicarbonate. The spleen was the most sensitive and reproducible organ for detection of dose- dependent systemic infection. Illness was only observed in animals exposed to doses of 10(8) cfu or more. At lower doses, histopathological changes in the gastrointestinal tract were observed, but these were not accompanied b y illness. Marked changes in numbers and types of white blood cells, as wel l as delayed-type hyperresponsiveness, indicated a strong, dose-dependent c ellular immune response to Salm. Enteritidis. Conclusions: The rat model is a sensitive and reproducible tool for studyin g the effects of oral exposure to Salm. Enteritidis over a wide dose range. Significance and Impact of the Study: The rat model allows controlled quant ification of different factors related to the host, pathogen and food matri x on initial stages of infection by food-borne bacterial pathogens.