Although 18 enterococcal species have been isolated from human infections, E. faecalis and E. faecium cause the overwhelming majority of enterococcal infections.

• Enterococci are the second most common cause of nosocomial infection (after staphylococci), with roughly equal numbers of cases caused by E. faecalis and E. faecium.
• Colonization with VRE (as opposed to antibiotic-susceptible strains) predisposes to enterococcal infection. Risk factors for VRE colonization include prolonged hospitalization; long antibiotic courses; hospitalization in long-term care facilities, surgical units, and/or ICUs; organ transplantation; renal failure; high APACHE scores; and physical proximity to pts colonized with VRE.