Vancomycin-resistant Enterococci may obtain nutritional support by scavenging carbohydrate fragments generated during mucin degradation by the anaerobic microbiota of the colon

Abstract

Vancomycin-resistant Enterococcus (VRE) is an important nosocomial pathogen that colonizes the intestinal tract. The substrates that provide nutritional support for VRE in the colon are not known. We tested the hypothesis that enzymatic breakdown of complex polysaccharides and glycoconjugates by other members of the indigenous microbiota could provide a source of nutrients for VRE. Nine vancomycin-resistant E. faecium strains were unable to ferment complex plant polysaccharides or hog gastric or bovine submaxillary mucin; however, each of the strains was able to ferment monosaccharides that are components of mucins and plant polysaccharides. Preincubation of hog gastric mucin with partially purified enzyme mixtures obtained from supernatants of Ruminococcus torques or a human stool specimen resulted in release of monosaccharides that supported growth of VRE. These results suggest that enzymatic breakdown of complex polysaccharides such as mucin by members of the indigenous microbiota may provide a source of nutritional support for VRE.