THE EFFECT OF ANTISEBORRHOEIC AGENTS ON P ITYROSPORUM-OVALE IN-VITRO

Thirty strains of the lipophilic yeast Pityrosporum ovale were isolate d from patients suffering from seborrhoeic dermatitis and dandruff and tested for susceptibility both to some classic antifungal agents and to several primarily non-antimycotic drugs. Minimal inhibitory concent rations (MIC) of altogether eleven agents were measured by the agar di lution technique. As expected, the tested imidazoles showed a good inh ibition of growth of Pityrosporum. The most effective agents were keto conazole (MIC 0.1 mug/ml) and itraconazole (MIC 0.05 mug/ml for some s trains). MIC for fluconazole, clotrirnazole and tioconazole were also low, indicating a good inhibition of Pityrosporum. In contrast, the ra nge of MIC for bifonazole was moderate to high (for some strains 12.5- 25 mug/ml). For zinc pyrithion a very good in vitro efficacy (MIC 0.78 -1.56 mug/ml) was dedicated. The MIC for selenium disulphide was 1.56- 3.13 mug/ml. ml. The antipsoriatic drugs dithranol and liquor carbonis detergens also inhibited growth of all Pityrosporum ovale strains inv estigated but only at higher concentrations.