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).