Mupirocin is a topical antibiotic used to treat bacterial infections. Originally derived from the bacterium *Pseudomonas fluorescens*, it is particularly effective against Gram-positive bacteria like *Staphylococcus aureus*. The medication is often used in the form of a cream or ointment for skin infections such as impetigo, folliculitis, and certain cases of methicillin-resistant *Staphylococcus aureus* (MRSA).