Citrobacter amalonaticus strain:C3H Genome sequencing. Citrobacter amalonaticus strain:C3H

The gut microbiota plays a crucial role in susceptibility to enteric pathogens, including Citrobacter rodentium, a model extracellular mouse pathogen that colonises the colonic mucosa. Following withdrawal of antibiotic treatment, 35% of C3H/HeN mice were able to prevent C. rodentium commensalisation in the gut lumen. These mice presented a bloom of a commensal species, Citrobacter amalonaticus, which inhibited the growth of C. rodentium in vitro in a contact-dependant manner and luminal growth of AIBC C. rodentium in vivo. Overall our data suggest that commensal species can confer colonisation resistance against closely-related pathogenic species.