The surface rhamnopolysaccharide epa of Enterococcus faecalis is a key determinant of intestinal colonization

J Infect Dis. 2015 Jan 1;211(1):62-71. doi: 10.1093/infdis/jiu402. Epub 2014 Jul 17.

Abstract

Enterococcus faecalis is a commensal bacterium of the human intestine and a major opportunistic pathogen in immunocompromised and elderly patients. The pathogenesis of E. faecalis infection relies in part on its capacity to colonize the gut. Following disruption of intestinal homeostasis, E. faecalis can overgrow, cross the intestinal barrier, and enter the lymph and bloodstream. To identify and characterize E. faecalis genes that are key to intestinal colonization, our strategy consisted in screening mutants for the following phenotypes related to intestinal lifestyle: antibiotic resistance, overgrowth, and competition against microbiota. From the identified colonization genes, epaX encodes a glycosyltransferase located in a variable region of the enterococcal polysaccharide antigen (epa) locus. We demonstrated that EpaX acts on sugar composition, promoting resistance to bile salts and cell wall integrity. Given that EpaX is enriched in hospital-adapted isolates, this study points to the importance of the epa variability as a key determinant for enterococcal intestinal colonization.

Keywords: Enterococcus faecalis; intestinal colonization; opportunistic infection; pathobiont; rhamnopolysaccharide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Surface / genetics
  • Antigens, Surface / metabolism*
  • Bile Acids and Salts / genetics
  • Bile Acids and Salts / metabolism
  • Cell Wall / genetics
  • Cell Wall / metabolism
  • Drug Resistance, Microbial
  • Enterococcus faecalis / genetics
  • Enterococcus faecalis / growth & development*
  • Enterococcus faecalis / metabolism*
  • Enterococcus faecalis / pathogenicity
  • Genes, Bacterial
  • Glycosyltransferases / genetics
  • Glycosyltransferases / metabolism
  • Gram-Positive Bacterial Infections / microbiology
  • Intestines / microbiology*
  • Male
  • Mice
  • Microbiota / genetics
  • Polysaccharides / genetics
  • Polysaccharides / metabolism*
  • Rhamnose / metabolism

Substances

  • Antigens, Surface
  • Bile Acids and Salts
  • Polysaccharides
  • Glycosyltransferases
  • Rhamnose