Quantitative Microbiology of the Scalp in Non-Dandruff, Dandruff, and Seborrheic Dermatitis

Abstract

The composition of the scalp microflora was assessed quantitatively in normal individuals and in patients with dandruff and seborrheic dermatitis, disorders characterized by increasing scalin. Three organisms were constantly found: (1) Pityrosporum, (2) aerobic cocci, and (3) Corynebacterium acnes. Pitrosporum (mainly Pityrosporum ovale) made up 46% of the total microflora in normals, 74% in dandruff, and 83% in seborrheic dermatitis. The geometric mean number of organisms per cm2 in non-dandruff subjects was 5.04 × 105; 9.22 × 105 in dandruff subjects; and 6.45 × 105 in those with seborrheic dermatitis. The cocci were dominantly Baird-Parkertype SII and no quantitative or qualitative change occurred in the scaling disorders. C. acnes comprised 26% of the flora on the normal scalp, 6% in dandruff, and only 1% in seborrheic dermatitis. These results differ significantly from previous reports which describe a much more complex microflora and suggest an etiologic role for microorganisms in dandruff