Mupirocin is an antibiotic used as a topical treatment for various bacterial skin infections, often found in ointments or creams. This unique drug was isolated in the early 1970s from the bacterium Pseudomonas fluorescens. Its primary role is to eliminate or prevent bacterial growth on the skin, making it a valuable tool for localized infections.
How Mupirocin Works
Mupirocin belongs to a distinct class of antibiotics known as monoxycarbolic acids, sometimes referred to as pseudomonic acid antibiotics. Its unique mechanism of action differentiates it from many other antimicrobial agents.
Mupirocin works by specifically and reversibly binding to an enzyme within bacteria called isoleucyl-tRNA synthetase. This enzyme is responsible for attaching the amino acid isoleucine to its corresponding transfer RNA (tRNA), a step fundamental for bacterial protein synthesis. By inhibiting this process, mupirocin prevents bacteria from producing the proteins they need to grow and replicate. This disruption of protein synthesis leads to bacterial cell death, classifying mupirocin as bactericidal at topical concentrations. The structural similarity between a mupirocin protein side chain and the bacterial isoleucyl-transfer RNA binding site allows mupirocin to incorporate into the binding site, obstructing protein and RNA synthesis.
What Mupirocin Treats
Mupirocin is primarily prescribed for bacterial skin and soft tissue infections. It is effective against a wide range of Gram-positive bacteria, including Staphylococcus aureus (encompassing MRSA) and various Streptococcus species. It also shows activity against certain Gram-negative organisms like Escherichia coli and Haemophilus influenzae.
Common conditions treated include impetigo, a highly contagious skin infection caused by Staphylococcus aureus and Streptococcus pyogenes. Beyond treating existing infections, mupirocin is also used to eradicate nasal carriage of MRSA, a measure employed to prevent surgical site infections or reduce infection risk in healthcare settings. It can be applied prophylactically to prevent infection in minor burns, cuts, or other clean lesions.
Key Information for Users
When using mupirocin, mild side effects at the application site are common, such as burning, stinging, itching, or redness. Less common reactions may include headache or nausea. Serious allergic reactions, though rare, can occur and may present as hives, dizziness, wheezing, or swelling of the face, lips, tongue, or throat.
Avoid getting mupirocin in the eyes, nose (unless using the specific nasal formulation), or mouth; rinse thoroughly with water if accidental contact occurs. Patients should always complete the full course of treatment as prescribed, even if symptoms improve, to ensure the infection is fully cleared and to minimize the risk of developing antibiotic resistance. Mupirocin does not typically exhibit cross-resistance with other antibiotic classes, making it a valuable option, especially against resistant strains like MRSA.