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EMBO Rep. 2016 Sep;17(9):1281-91. doi: 10.15252/embr.201642282. Epub 2016 Jul 18.

Strain competition restricts colonization of an enteric pathogen and prevents colitis.

Author information

1
Department of Microbiology, University of Chicago, Chicago, IL, USA Interdisciplinary Scientist Training Program, University of Chicago, Chicago, IL, USA.
2
Department of Pathology, University of Chicago, Chicago, IL, USA.
3
Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, USA.
4
Department of Microbiology, University of Chicago, Chicago, IL, USA Department of Pediatrics, University of Chicago, Chicago, IL, USA jbubeckw@peds.bsd.uchicago.edu.

Abstract

The microbiota is a major source of protection against intestinal pathogens; however, the specific bacteria and underlying mechanisms involved are not well understood. As a model of this interaction, we sought to determine whether colonization of the murine host with symbiotic non-toxigenic Bacteroides fragilis could limit acquisition of pathogenic enterotoxigenic B. fragilis We observed strain-specific competition with toxigenic B. fragilis, dependent upon type VI secretion, identifying an effector-immunity pair that confers pathogen exclusion. Resistance against host acquisition of a second non-toxigenic strain was also uncovered, revealing a broader function of type VI secretion systems in determining microbiota composition. The competitive exclusion of enterotoxigenic B. fragilis by a non-toxigenic strain limited toxin exposure and protected the host against intestinal inflammatory disease. Our studies demonstrate a novel role of type VI secretion systems in colonization resistance against a pathogen. This understanding of bacterial competition may be utilized to define a molecularly targeted probiotic strategy.

KEYWORDS:

colonization resistance; enterotoxigenic Bacteroides fragilis; in vivo strain competition; probiotics; type VI secretion

PMID:
27432285
PMCID:
PMC5007561
DOI:
10.15252/embr.201642282
[Indexed for MEDLINE]
Free PMC Article

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