Vancomycin is a powerful antibiotic drug active against Gram-positive bacteria. It was once used by doctors as the "drug of last resort" only after treatment with other antibiotics had failed. Now that bacteria are more frequently antibiotic resistant, vancomycin has increasingly become a first line defense when faced with apparent staphylococcal infections in a patient where antibiotic resistance can reasonably be anticipated.
Vancomycin acts by hindering cell-wall synthesis by blocking glycopeptide polymerization, and thus is not active against Gram-negative bacteria. It is administered intravenously and must be used cautiously in patients with poor renal or hepatic function, or when given in conjunction with other nephrotoxic drugs.
Intravenous vancomycin can be used instead of penicillin for endocarditis prophylaxis in patients undergoing dental procedures who are allergic to penicillin.
An oral form of vancomycin is sometimes used in treating pseudomembranous enterocolitis, which is a bowel condition caused by overuse of antibiotics: it is effective because vancomycin cannot be absorbed from the bowel, and so its concentration in the bowel is quite high. This same property renders oral vancomycin useless for systemic infections.
As of July 2002, there were reports that a woman in the US city of Detroit is infected by a strain of Staphylococcus aureus that is resistant to vancomycin. She is being kept in isolation to prevent the infection from being spread to others.
See also: superbug