A topical applications is used to treat and prevent the spread of nail infections or onychomycosis caused by bacteria, fungi and other pathogens. The topical application has a composition that comprises, as an active ingredient, at least one species selected from the group consisting of 2,2′-(alkyldioxy) bis-(alkyl-1,3,2-dioxaborinane) and 2,2′-oxybis(alkyl-1,3,2-dioxaborinane). More specifically, the composition comprises, as an active ingredient, at least one member selected from the group consisting of 2,2′-(1-methyltrimethylene dioxy) bis-(4-methyl-1, 3, 2-dioxaborinane) and 2,2′-oxybis (4, 4, 6-trimethyl-1, 3, 2-dioxaborinane).