Mupirocin resistance: clinical and molecular epidemiology.

The antistaphylococcal activity of topical mupirocin has made it an attractive agent for the treatment of asymptomatic colonization with Staphylococcus aureus. Increasing use has been associated with the emergence of mupirocin resistance in staphyloccoci, and failure of therapy has been associated with the isolation of strains exhibiting high-level resistance (MIC > 500 micrograms/mL). Fortunately, low-level mupirocin resistance (MIC < 100 micrograms/mL) occurs most commonly. Because a novel gene encoding for mupirocin resistance resides in both low-level and high-level resistant strains, the emergence of low-level mupirocin resistance may not be as epidemiologically insignificant as previously thought.