Vancomycin-resistant enterococci: the clinical effect of a common nosocomial pathogen.

Enterococcus spp. is now the third most common pathogen among hospitalized patients, accounting for nearly 12% of nosocomial infections. Enterococcus faecalis is the most prevalent enterococcal species (85%-89%), whereas Enterococcus faecium accounts for 10%-15% of enterococcal isolates. Only 5% of E. faecalis isolates are resistant to glycopeptides. E. faecium has also been shown to be resistant to nonglycopeptide compounds, such as penicillins (97%), high-level gentamicin (52.1%), and high-level streptomycin (58.3%). Numerous risk factors for vancomycin-resistant enterococci (VRE) have been identified, including as length of hospital- or ICU-stay, proximity to a hospitalized, colonized VRE, patient severity of illness, renal failure, recent surgery, immunosuppression, and organ recipient status. An important risk factor is prior exposure to antibiotics such as vancomycin, ceftazidime, ciprofloxacin, and metronidazole, as well as the number and duration of recent antibiotics. Interventions to reduce nosocomial VRE cross-transmission have also been studied. Using gowns in addition to gloves diminished the incidence of VRE in one study, but had a negligible effect in a second study. Studies have shown that in many cases (> 60%) vancomycin usage is inappropriate. While controlling the use of vancomycin alone has only variably diminished VRE colonization, other efforts such as narrowing the spectrum of antibiotics, antiseptics, and reducing immunosuppression may be salutary. Attempts to eradicate VRE intestinal carriage with enteral agents (bacitracin, tetracycline + rifampin, novobiocin) have been reported but seem to have only a transient effect. Non-antimicrobial interventions such as removal of intravenous or bladder catheters and/or surgical or percutaneous drainage may be beneficial. In addition, the development of new antimicrobial agents such as streptogramins, glycopeptides, everninomicins, and oxazalididones will hopefully play an important role in reducing morbidity from these pathogens.