Role of microorganisms in dandruff.

The role of microorganisms in dandruff was studied, by suppressing individually and then collectively the three major components of the scalp microflora. The effect on dandruff was assessed subjectively by clinical grading and objectively by the corneocyte count. No effect on dandruff was demonstrated when scalp organisms were suppressed. In the second group of experiments, dandruff was suppressed by selenium sulfide shampooling and the effect of continued suppression of Pityrosporum with topically applied amphotericin was measured. According to our criteria, dandruff returned to pretreatment levels, despite continued suppression of Pityrosporum. The studies demonstrate that the increased number of scalp microorganisms found in dandruff occurs as a secondary event to increased nutrients and that scalp organisms play no primary role in the pathogenesis of dandruff.