In vitro antimicrobial activity of tioconazole and its concentrations in vaginal fluids following topical (vagistat-1 6.5%) application.

In vitro assays demonstrated that clinical yeasts were significantly more inhibited by tioconazole (MIC50, < or = 0.5 microgram/ml) than by fluconazole (MIC50, 8 micrograms/ml). Tioconazole also exhibited high potency against most molds (Alterneria spp. and Acremonium spp.). All Candida tropicalis isolates had MICs of 8 micrograms/ml, four-fold greater than any other Candida spp. Generally Gram-negative bacteria were less susceptible to tioconazole. Moraxella catarrhalis (MIC90, 2 micrograms/ml) was the most susceptible Gram-negative species. Staphylococci and enterococci were the most susceptible to tioconazole Gram-positive species (MIC50s, 1-8 micrograms/ml). Bacterial species associated with vaginosis. [Gardnerella vaginalis (MIC90, 16 micrograms/ml), Mobiluncus spp. (MIC90, 16 micrograms/ml) and Prevotella biviadisiens (MIC90, 64 micrograms/ml)] were inhibited by tioconazole. Isolates of Lactobacillus spp. were most resistant (MIC90, > or = 256 micrograms/ml) to tioconazole. Vaginal fluid levels of tioconazole (mean, 91.4 micrograms/ml) persisted above the MIC90 levels (1-64 micrograms/ml) for most fungal and bacterial pathogens for 72 h in 19 evaluable female human subjects receiving 300 mg tioconazole in an intravaginal ointment.