Mupirocin

Published 31.6.21

Nature

Fermentation product of Pseudomonas fluorescence.

Mechanism of action

Mupirocin inhibits bacterial protein synthesis by binding reversibly to the bacterial isoleucyl transfer-RNA synthetase enzyme. This mechanism is unique and hence no cross resistance with other antibiotics has been reported.

It prevents bacterial protein synthesis.

Mechanism of resistance

  • Low level resistance (MIC 8-256) – Low level resistance is chromosomal; it is due to point mutation in ileS gene. This gene codes for isoleucyl tRNA synthetase.

  • High level resistance (MIC>512) – Plasmid; mupA gene mediated – which generates additional isoleucyl tRNA transferase.

  • Risk of resistance is higher in cases of – long-term use, use in presence of foreign body (NG tube), decubitus ulcer.

PK/PD

  • Inactivated in plasma and hence it is only used topically.

  • Bacteriostatic near MIC and bactericidal at higher concentration.

  • Poorly absorbed when used topically, absorbed drug get metabolised in the liver.

Spectrum

  • Staph aureus (including MRSA, VISA, VRSA), strep, CoNS, Enterococci, Streptococcus bovis has high MIC,

  • Micrococcus resistant. Corynebacterium and anaerobic gram positives are resistant.

  • Haemophilus, Moraxella, Neisseria, Bordetella, Pasteurella sensitive.

Adverse effect

  • Burning, stinging, itching, rash, headache.

  • Mupirocin prep containing polyethylene glycol should be used with caution in renal impairment.

Use

Eradication regimen for MRSA – anterior nares BD X 5 days. [Cochrane review 2008]

NOT indicated for the prophylaxis of clean surgical wounds.