Abstract

Dose-response models are an essential part of quantitative microbiological risk assessment, but not many appropriate data are available for this purpose. Human volunteer studies provide only limited information. Therefore, an animal model for infection with human enteropathogenic bacteria is being developed. Suckling mice were found to be only marginally sensitive to inoculation with varying doses of Salmonella enteritidis, and there was no dose-response relationship. Adult rats could be infected with high doses of Salmonella enteritidis, Escherichia coli O157 or Campylobacter jejuni. Overnight starvation and neutralisation of gastric acid markedly increased the susceptibility of the animals to oral infection. Under these conditions, S. enteritidis induced severe systemic illness, whereas E. coli O157 and C. jejuni colonised the intestinal tract without causing clinical disease. Although diarrhoeal symptoms were not detected, animals challenged with C. jejuni had increased moisture content in the faeces and some animals showed signs of typhlitis/colitis.