Growth inhibition of Candida albicans and other medically important yeasts by vaginal contraceptive products.

The antifungal effects of two commercially available spermicidal gels (Conceptrol, produced by Ortho Pharmaceutical, Raritan, N.J., and Koromex, produced by Schmid Laboratories, Little Falls, N.J.) as well as pure nonoxynol-9 and boric acid (both components of vaginal contraceptive products) were tested against 50 clinical yeast isolates by the agar dilution method. The formulated products exerted comparable dose-dependent inhibitory effects against all yeasts tested. A 3-fold dilution of the formulated spermicidal products inhibited 90% of the yeast strains tested. To determine if the antifungal effect was due to the spermicidal detergent nonoxynol-9, this compound was tested for antifungal activity but was completely ineffective against Candida albicans in concentrations up to 10%. Boric acid, present in at least one of the products (Koromex), inhibited representative yeasts at a concentration of 0.4%. The relationship of pH and oxygen tension to inhibition by the commercial spermicides was also investigated. The pH values tested ranged from 4 to 7 and had little effect on inhibition; anaerobiosis at pH 7 slightly reduced the inhibitory activity of Conceptrol gel.