About Mupirocin A naturally antibiotic isolated from Pseudomonas fluorescens, Antibiotic. Mechanism of Action of Mupirocin Mupirocin exerts its action by reversibly binding to isoleucyl transfer RNA synthetase and inhibits the enzyme activity. This enzyme is necessary for the synthesis of proteins in the bacteria. Inhibition of isoleucyl transfer RNA synthetase results in inhibition of protein synthesis and produce microbicidal action. It is more active against gram positive bacteria as compared to gram negative bacteria. Indications for Mupirocin Bacterial skin infections: 1. Impetigo 2. Infected eczema 3. Folliculitis 4. Eradication of nasal colonization of Methicillin resistant S.aureus