Implant infections due to enterococci: Role of capsular polysaccharides and biofilm

Enterococci are natural inhabitants of the gastrointestinal tract and of the female genital tract of humans and many animals. In recent years, enterococci have been increasingly recognized as important human pathogens causing infections associated with medical devices. Their resistance to most antimicrobial agents and their ability to form biofilm has contributed to the increasing incidence of nosocomial enterococcal infections. Enterococci possess a capsular polysaccharide composed of a glycerol-teichoic acid-like molecule consisting of repeating units of 6-alpha-D-glucose-1-2-glycerol-3-PO4, substituted on carbon 2 with a alpha-2, 1-linked molecule of glucose. Using both immunologic and genetic data E. faecalis can be assigned to specific serotypes based on capsular polysaccharides. Clinical examples of foreign-body infections due to enterococci are described, comprising infections of artificial joints, implanted intravascular catheters, artificial hearts and artificial valves, stents, liquor shunt devices, and intraocular infections. Methods to prevent and/or treat enterococcal infections are presented.