The threat of vancomycin resistance.

Vancomycin, produced in 1958, an essential antibiotic in the modern age, often is reserved for use in patients who are gravely ill or for infections caused by organisms resistant to penicillin, cephalosporin, or other antibiotics. Bacterial resistance to vancomycin has caused great concern among many healthcare professionals. First reported in 1986 in Europe and in 1988 in the United States, vancomycin-resistant enterococci (VRE) have become a major cause of nosocomial infections. During this time, scattered reports of clinical infections caused by vancomycin-resistant coagulase-negative staphylococci also were reported. Recently, enterococci that require vancomycin in media for growth, vancomycin-dependent enterococci (VDE), have been reported to cause clinically significant infections. Vancomycin or other glycopeptide intermediately resistant Staphylococcus aureus (VISA/GISA) also has emerged. The mechanisms of resistance to vancomycin for VRE, and probably for VISA/GISA, relate to the acquired ability of these organisms to circumvent the vancomycin-mediated disruption of bacterial cell wall synthesis. Risk factors that lead to VRE colonization or infection include prior antibiotic therapy, prolonged hospitalization, hospitalization in an intensive care unit, concomitant serious medical and surgical illnesses, exposure to equipment contaminated with VRE, and exposure to patients with VRE. Patients colonized or infected with VRE, healthcare workers with contaminated hands, and environmental surfaces in healthcare facilities are major reservoirs of VRE. Risk factors for VDE and VISA/GISA are less well understood, although both organisms emerge in patients receiving vancomycin or other glycopeptide antibiotics. Infection and antibiotic control procedures for both organisms, including restriction of vancomycin use, optimization of the antibiotic formulary, education of hospital personnel, early detection and reporting of vancomycin resistance, isolation of colonized patients, and appropriate cleansing of the environment are used to prevent the spread of these organisms in healthcare settings.