Stressor exposure has prolonged effects on colonic microbial community structure in Citrobacter rodentium-challenged mice

Stressor exposure significantly affects the colonic mucosa-associated microbiota, and exacerbates Citrobacter rodentium-induced inflammation, effects that can be attenuated with probiotic Lactobacillus reuteri. This study assessed the structure of the colonic mucosa-associated microbiota in mice exposed to a social stressor (called social disruption), as well as non-stressed control mice, during challenge with the colonic pathogen C. rodentium. Mice were exposed to the social stressor or home cage control conditions for six consecutive days and all mice were challenged with C. rodentium immediately following the first exposure to the stressor. In addition, mice received probiotic L. reuteri, or vehicle as a control, via oral gavage following each stressor exposure. The stressor-exposed mice had significant differences in microbial community composition compared to non-stressed control mice. This difference was first evident following the six-cycle exposure to the stressor, on Day 6 post-C. rodentium challenge, and persisted for up to 19 days after stressor termination. Mice exposed to the stressor had different microbial community composition regardless of whether they were treated with L. reuteri or treated with vehicle as a control. These data indicate that stressor exposure affects the colonic microbiota during challenge with C. rodentium, and that these effects are long-lasting and not attenuated by probiotic L. reuteri.