Introduction
Mupirocin is a topical antibiotic medication primarily used for the treatment of skin infections caused by susceptible strains of bacteria. Originally isolated from Pseudomonas fluorescens, it represents a unique class of antibiotics with a distinctive mechanism of action. Mupirocin is particularly valued for its efficacy against Staphylococcus aureus, including methicillin-resistant strains (MRSA), making it an important agent in both community and healthcare settings.
Mechanism of Action
Mupirocin exerts its antibacterial effect through reversible inhibition of bacterial isoleucyl-tRNA synthetase, an enzyme essential for protein synthesis. By competitively binding to the enzyme's active site, mupirocin prevents the incorporation of isoleucine into growing peptide chains, thereby halting bacterial protein production. This mechanism is bacteriostatic at lower concentrations and bactericidal at higher concentrations against susceptible organisms. The drug's unique target site minimizes cross-resistance with other antibiotic classes.
Indications
Mupirocin is FDA-approved for:
- Topical treatment of impetigo caused by Staphylococcus aureus, Streptococcus pyogenes, and beta-hemolytic streptococci
- Eradication of nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) in adult patients and healthcare workers
- Secondary infected traumatic skin lesions due to susceptible organisms
Off-label uses include:
- Prophylaxis against surgical site infections in nasal carriers of S. aureus
- Treatment of other superficial skin infections caused by susceptible gram-positive bacteria
Dosage and Administration
Topical ointment (2%):- Apply a small amount to affected area 3 times daily
- Cover treated area with gauze dressing if desired
- Duration: 7-10 days for skin infections
- Apply approximately one-half of the single-use tube to each nostril twice daily
- Duration: 5 days for decolonization
- Renal impairment: No dosage adjustment required
- Hepatic impairment: No dosage adjustment required
- Pediatrics: Safety established for children ≥2 months for topical use
- Geriatrics: No specific dosage adjustments required
Pharmacokinetics
Absorption: Minimal systemic absorption following topical application (<1% of administered dose). Detectable serum concentrations are unlikely with appropriate use. Distribution: Remains primarily at the site of application with minimal tissue penetration. Metabolism: Rapidly metabolized to inactive monic acid in the skin and systemically. Elimination: Primarily excreted renally as inactive metabolites. Half-life is approximately 20-40 minutes following systemic administration (not clinically relevant for topical use).Contraindications
- Hypersensitivity to mupirocin or any component of the formulation
- Use in the eyes or for ophthalmic purposes
- Use of nasal formulation for skin applications
Warnings and Precautions
- Prolonged use may result in overgrowth of nonsusceptible organisms, including fungi
- Use with caution in patients with moderate to severe renal impairment (theoretical concern)
- Avoid extensive application to large body surface areas due to potential for systemic absorption
- Discontinue use if irritation or hypersensitivity reactions occur
- Nasal application may cause alterations in sense of taste or smell
Drug Interactions
No clinically significant drug interactions have been documented due to minimal systemic absorption. However, theoretical interactions with other topical products applied to the same area may occur:
- Concurrent use with other topical medications may alter absorption or cause physical incompatibility
- Avoid concomitant use with nasal corticosteroid sprays when using nasal formulation
Adverse Effects
Common (≥1%):- Application site reactions: burning, stinging, pain, itching
- Nasal formulations: rhinitis, pharyngitis, taste perversion, dry nose
- Headache
- Contact dermatitis
- Nausea
- Erythema
- Skin dryness
- Anaphylaxis (extremely rare)
- Angioedema
- Systemic allergic reactions
Monitoring Parameters
- Clinical response to therapy (resolution of infection symptoms)
- Signs of superinfection or fungal overgrowth
- Local skin reactions or irritation
- For nasal decolonization: follow-up cultures to confirm eradication when indicated
- Renal function in patients with pre-existing renal impairment receiving extensive application
Patient Education
- Use exactly as prescribed; complete full course of therapy
- Wash hands before and after application
- Avoid contact with eyes, mouth, and other mucous membranes
- Do not apply to large areas of broken skin unless directed by healthcare provider
- Report any signs of allergic reaction (rash, itching, swelling) or worsening infection
- Store at room temperature; do not freeze
- Nasal formulation: Avoid blowing nose immediately after application
- Do not share medication with others
References
1. FDA Prescribing Information: Mupirocin Ointment (2022) 2. Lexicomp Online: Mupirocin Monograph (2023) 3. Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing (2023) 4. Stevens DL, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections. Clin Infect Dis. 2014;59(2):e10-e52 5. van Rijen MML, et al. Mupirocin ointment for preventing Staphylococcus aureus infections in nasal carriers. Cochrane Database Syst Rev. 2008;(4):CD006216 6. Dryden MS. Complicated skin and soft tissue infection. J Antimicrob Chemother. 2010;65 Suppl 3:iii35-iii44 7. Zervos MJ, et al. Mupirocin resistance in staphylococci: trends and therapeutic implications. Curr Opin Infect Dis. 2019;32(4):326-332