Clinical meaning
Vancomycin-resistant Enterococcus (VRE) refers to strains of Enterococcus bacteria -- primarily Enterococcus faecium and Enterococcus faecalis -- that have acquired genetic mutations or mobile genetic elements (plasmids and transposons) conferring resistance to vancomycin, a glycopeptide antibiotic traditionally considered a last-resort treatment for gram-positive infections. Enterococci are gram-positive, facultatively anaerobic cocci that normally colonize the gastrointestinal tract, female genital tract, and oral cavity as part of the normal flora. These organisms are intrinsically resistant to many commonly used antibiotics, including cephalosporins, aminoglycosides (low-level), and clindamycin. Vancomycin resistance develops through acquisition of the vanA or vanB gene clusters, which alter the target site (D-alanyl-D-alanine terminus) on the bacterial cell wall precursor peptidoglycan, replacing the terminal D-alanine with D-lactate. This modification reduces vancomycin binding affinity by approximately 1000-fold, rendering the antibiotic ineffective. VRE causes healthcare-associated infections including urinary tract infections, bacteremia, wound infections, intra-abdominal infections, and rarely endocarditis. VRE can survive on environmental surfaces (bed rails, doorknobs, stethoscopes, blood pressure cuffs) for days to weeks, facilitating transmission in healthcare settings. Transmission occurs primarily through direct contact with colonized or infected patients, or through contact with contaminated surfaces and equipment. The practical nurse plays a critical role in preventing VRE transmission through strict adherence to contact precautions, meticulous hand hygiene, and proper environmental cleaning. Risk factors for VRE colonization and infection include prolonged hospitalization, prior antibiotic exposure (especially vancomycin, third-generation cephalosporins, and fluoroquinolones), immunosuppression, proximity to colonized patients, and residence in long-term care facilities. Patients may be colonized (carrying VRE without symptoms) or infected (VRE causing active disease). Colonized patients serve as reservoirs for transmission and may develop infection if they become immunocompromised or undergo invasive procedures.