An evaluation of the antifungal effect of bifonazole on Torulopsis glabrata and Candida albicans under various in vitro test conditions.

1-[(4-Biphenylyl)-phenylmethyl]-1H-imidazole (bifonazole, Bay h 4502, Mycospor) showed in vitro significant inhibitory activity against Torulopsis glabrata, Candida albicans, Pityrosporum ovale, Corynebacterium acnes and Staphylococcus epidermidis. The antifungal activity of bifonazole against T. glabrata and C. albicans varied with the in vitro test conditions. There was a tendency for minimal inhibitory concentrations to increase as fungal inoculum size was increased and as incubation time was prolonged. For T. glabrata, but not for C. albicans, minimal inhibitory concentrations were lower in liquid than on solid culture media. The antifungal activity was less pronounced at low pH values. Because of these variations laboratory tests for the in vitro determination of antifungal sensitivities should be carried out under standardized test conditions such as small inocula, a limited incubation period and appropriate culture media. The solubility of bifonazole in aqueous solution is very low. In addition, more bifonazole dissolves at low than at high pH values.