Detection of mupirocin-resistant Staphylococcus aureus isolated from skin infections

We examined the MIC of mupirocin against Staphylococcus aureus strains isolated from skin infections between April 1996 and August 1997. None of the 32 S. aureus strains collected between April 1996 and September 1996 showed mupirocin-resistance, but 3 of the 58 S. aureus strains collected between October 1996 and August 1997 were found to be mupirocin-resistant with a MIC of 32 μg/mL. The 3 patients from whom the mupirocin-resistant S. aureus strains were isolated were outpatients with no previous mupirocin ointment treatment. The 3 mupirocin-resistant S. aureus strains were regarded as different strains on the basis of their coagulase typing, enterotoxin production, and antibiotic sensitivity. Our results suggest that the emergence of mupirocin-resistant S. aureus should be carefully monitored in Japan. Mupirocin ointment should be used only to eradicate nasal carriage of methicillin-resistant S. aureus and long-term use of the ointment should be strictly avoided.