The present invention relates to the use of one or more compounds selected from the following: caffeic acid, thymol, aspirin, benzydamine hydrochloride, diclofenac sodium, flurbiprofen, ibuprofen, indomethacin, trifluoperazine hydrochloride, chlorprothixene hydrochloride, triflupromazine hydrochloride, suloctidil, thioridazine hydrochloride, dichlorophen, saccharin and piroxicam, in combination with a polymyxin selected from colistin or polymyxin B or a pharmaceutically acceptable derivative thereof, for use in the treatment of a microbial infection, and in particular for killing clinically latent microorganisms associated with microbial infections. The invention also provides a combination comprising suloctidil or a pharmaceutically acceptable derivative or prodrug thereof, and a polymyxin selected from polymyxin E and polymyxin B or a pharmaceutically acceptable derivative thereof. This combination is particularly useful for the treatment and/or prevention of microbial infections.