Preview New antimicrobial pathogens resistant to vancomycin are wreaking havoc in medical centers throughout the nation. Their tendency to colonize or infect severely ill, hospitalized patients who have undergone invasive procedures and received prolonged courses of antimicrobial therapy is alarming. The most potent weapon in the physician's arsenal against these enemies is familiarity with their key features, with the guidelines for prudent use of drug therapy, and with the precautionary measures necessary to limit contact and spread.