Mupirocin is an antibiotic that inhibits isoleucyl-tRNA synthetase in bacterial cell walls, weakening the growth of bacteria with an MIC value of 0.05 µg/ml in Staphylococcus aureus.It is mainly used as an antibacterial agent against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA).
MRSA can resist therapeutic treatment via causing chronic infections leading to high rate mortality, by causing a proteic biofilm, extracellular DNA or carbohydrate matrix that allows bacterial survival in unfavourable environments.
Because of the similarity between isoleucine and the antibiotics's epoxy side chain, Mupirocin can prevent the conversion of isoleucine and tARN to isoleucine-charged transfer RNA by binding the active centre of isoleucyl-tRNA syntethase and thus decreasing its cellular levels inside the cells, causing bacterial death.
Mupirocin is a strong acid as a form of a crystalline white powder, freely soluble in dichloromethane and acetone, slightly soluble in water. Its antibiotic activity is pH dependent, at pH between 4 and 9 in aqueous solutions, the activity is maintained; but outside this interval, molecular rearrangements occur with the formation of two isomers, without interconversion. Mupirocin is the most widely used topical antibiotic to control the MRSA outbreaks, for infections of soft tissue or skin and for nasal decolonization.
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