Potentiating effect of Mentha arvensis and chlorpromazine in the resistance to aminoglycosides of methicillin-resistant Staphylococcus aureus.

BACKGROUND This is the first report testing the antibiotic resistance-modifying activity of Mentha arvensis against MRSA (methicillin-resistant Staphylococcus aureus). MATERIALS AND METHODS In this study an ethanol extract of Mentha arvensis L. and chlorpromazine were tested for their antimicrobial activity alone or in combination with conventional antibiotics against MRSA strains. RESULTS A potentiating effect of this extract on gentamicin, kanamycin and neomycin was demonstrated. Similarly, a potentiating effect of chlorpromazine on the same aminoglycosides was observed, indicating the involvement of an efflux system in the resistance to these antibiotics. CONCLUSION It is therefore suggested that extracts from M. arvensis could be used as a source of plant-derived natural products with resistance-modifying activity, such as in the case of aminoglycosides, constituting a new weapon against bacterial resistance to antibiotics, as with chlorpromazine.