Compositions for treating microbial infections

A pharmaceutically acceptable composition comprising a quinolone antimicrobial or a pharmaceutically acceptable salt thereof and more than one divalent cation, said composition suitable for the treatment of an ophthalmic infection by topical ocular administration, and wherein said quinolone antimicrobial is finafloxacin at a concentration of 0.1 to 1.0 w/v %, said divalent cations are magnesium at a concentration of 1 to 100 mM, and zinc at a concentration of 1 to 100 mM, and said composition has a pH of 4.5 to 7.5, said composition further comprising sodium acetate at a concentration of 0.01 to 1.0 w/v %.