bioRxiv 2019, 808832
Oral infection is a preferred model for studying the natural mode of infection and pathogenesis of enteropathogens such as Yersinia enterocolitica and Y. pseudotuberculosis. The most often used methodology for oral infection in laboratories using mice consists of oral gavage with a feeding needle introduced in the stomach via the esophagus. In this study, we compared needle feeding to bread feeding as an alternative mode of bacterial administration. Upon needle feeding, using a bioluminescence-expressing strain of Y. pseudotuberculosis we observed at an early time post-infection a bioluminescent signal in the neck area together with a signal in the abdominal region, indicating two sites of bacterial colonization and multiplication. Bacteria were often detected in the esophagus and trachea, as well as in the lymph nodes draining the salivary glands, suggesting micro-lesions made during the introduction of the needle in the oral cavity and rapid bacterial draining to the proximal lymph nodes. We then tested an alternative mode of bacterial administration using small pieces of white bread containing bacteria. Upon bread feeding infection, mice exhibited a stronger bioluminescent signal in the abdominal region as compared by needle gavage and no signal was observed in the neck. Y. pseudotuberculosis incorporated into the bread is less succeptible to the acidic environment of the stomach and is more efficient in causing intestinal infection. Based on our observations, bread feeding constitutes a more natural feeding route which does not require specialized skills to perform, is less traumatic for the animal and results in infections that more closely mimic food-borne intestinal infections.