Enterococci are gram-positive cocci that are normal inhabitants of the gastrointestinal tract. However, they can also be significant pathogens, causing endocarditis and urinary tract, bloodstream, and wound infection (62). During the last decade, a dramatic increase in the occurrence of vancomycin-resistant enterococci (VRE) has been noted in hospitals within the United Kingdom and the United States (16, 87). For instance, a 9-year study from the United Kingdom determined that vancomycin resistance in Enterococcus faecium isolated in blood cultures reached 6.3% in 1993, 20% in 1995, and 24% in 1998 (87). According to the Centers for Disease Control and Prevention, the percentage of enterococcal isolates that were resistant to vancomycin reported by U.S. intensive care units (ICUs) increased from 0.3% in 1989 to 25.2% in 1999 (16). In a recently published international survey (57), the proportion of nosocomial enterococcal isolates in the United States that were resistant to vancomycin (17% in 1999) was much higher than the proportion of vancomycin-resistant enterococcal isolates from patients in the rest of the world (Fig. 1).