Vancomycin-resistant enterococci: Mechanisms and Clinical Observations. Clin Infect Dis 2001

Enterococci are not generally regarded as highly virulent bacterial pathogens. However, resistance to many antimicrobial drugs complicates treatment of enterococcal infections. Acquired resistance to high concentrations of glycopeptide antibiotics, specifically vancomycin, has exacerbated this problem. This article seeks to concisely review the mechanisms of that resistance and its effects on clinical management of enterococcal infections, as well as clinical microbiology and infection control. Enterococcus gallinarum and Enterococcus casseliflavus are rel-atively infrequent causes of human infection. As a result, the intrinsic resistance to low concentrations of vancomycin (MICs as high as 32 mg/mL) that is a characteristic of these species was little more than a curiosity to infectious diseases clinicians. In contrast, Enterococcus faecalis and Enterococcus faecium cause the great majority of enterococcal infections. When clinical isolates of these enterococcal species with acquired vancomycin resistance began to appear in the late 1980s, it prompted sig-nificant changes in testing of enterococci in the clinical micro-biology laboratory, infection control of enterococci, and treat