Mice colonized with the defined microbial community OMM19.1 are susceptible toC. difficileinfection without prior antibiotic treatment

Abstract

ABSTRACTDiverse gut microorganisms present in humans and mice are essential for the prevention of microbial pathogen colonization. However, antibiotic-induced dysbiosis of the gut microbiome reduces microbial diversity and allowsC. difficileto colonize the intestine. The Oligo Mouse Microbiota 19.1 (OMM19.1) is a synthetic community that consists of bacteria that are taxonomically and functionally designed to mimic the specific pathogen-free (SPF) mouse gut microbiota. Here, we examined the susceptibility of OMM19.1 colonized mice toC. difficileinfection at a range of infectious doses (103, 105, and 107spores) without prior antibiotic treatment. We found that mice colonized with OMM19.1 were susceptible toC. difficileinfection regardless of the dose. The clinical scores increased with increasingC. difficiledosage. Infection withC. difficilewas correlated with a significant increase inLigilactobacillus murinusandEscherichia coli, while the abundance ofBacteroides caecimuris, Akkermansia muciniphila, Extibacter muris, and Turicimonas murissignificantly decreased followingC. difficileinfection. Our results demonstrate that the OMM19.1 community requires additional bacteria to enable colonization resistance.