Mupirocin (pseudomonic acid A, or Bactroban or Centany) is an antibiotic originally isolated from Pseudomonas fluorescens. It is used topically, and is primarily effective against Gram-positive bacteria. Mupirocin is bacteriostatic at low concentrations and bactericidal at high concentrations.

It has a unique mechanism of action, which is selective binding to bacterial isoleucyl-tRNA synthetase, which halts the incorporation of isoleucine into bacterial proteins. Because this mechanism of action is not shared with any other antibiotic, mupirocin has few problems of antibiotic cross-resistance. It is a topical treatment for bacterial skin infections, for example, furuncle, open wounds etc. It is also useful in the treatment of methicillin-resistant Staphyolococcus aureus (MRSA), which is a significant cause of death in hospitalized patients who have received systemic antibiotic therapy. It is suggested, however, that mupirocin not be used for extended periods of time, or indiscriminately, as resistance does develop, and could, if it becomes widespread, destroy mupirocin's value as a treatment for MRSA. It may also result in overgrowth of non-susceptible organisms.

The original manufacturer's (GlaxoSmithKline) product is Bactroban.

It is now available as a generic manufactured by Ortho McNeil Pharmaceutical Inc called Centany.