Mupirocin (
pseudomonic acid A) is a novel topical
antibacterial agent which inhibits
bacterial protein and
RNA synthesis. It has excellent in vitro activity against staphylococci and most streptococci, but has less activity against other Gram-positive and most Gram-negative bacteria. Its rapid systemic metabolism means it will only be used topically which, combined with its novel chemical structure, should make cross-resistance less likely to occur than with other currently available topical
antibacterial agents.
Mupirocin 2%
ointment administered 2 or 3 times daily has shown excellent efficacy in both primary and secondary superficial skin
infections, usually with at least 80% of patients being clinically cured or markedly improved, and over 90% eradication of the bacterial pathogen involved. Efficacy in
impetigo and, to a somewhat lesser extent, infected
wounds has been particularly convincingly demonstrated, while in other secondary skin
infections the clinical response seen with
mupirocin was often similar to the high success rate of vehicle alone. Limited evidence suggests that
mupirocin may be as effective as
chlortetracycline,
fusidic acid,
neomycin and other
antibacterial agents, but more controlled, comparative studies are needed. The evidence of efficacy against nasal carriage of Staphylococcus aureus, including methicillin-resistant forms, is encouraging and currently work is being undertaken to improve the acceptability of the vehicle for this use. Side effects are limited to local reactions (in less than 3% of patients) and are no more frequent than observed with the vehicle alone. Thus,
mupirocin appears to be a useful addition to the agents available for the treatment of superficial primary skin
infections, such as
impetigo, although its precise place in
therapy remains to be established.