The microbial colonization of inflamed acne vulgaris lesions.

Seventy one papules in the early stages of inflammatory development were isolated from acne vulgaris affected skin and their content of micro-organisms characterized. The progress of lesions prior to excision was monitored by tracing an area of the upper back onto a transparent acetate sheet. This template was used the next day, and in some cases after 3 days, to identify inflamed lesions of less than 1 day and 2-3 days duration. These were biopsied, and pilosebaceous units isolated by micro-dissection, homogenized and microbial populations studied by viable counting and microscopy. Propionibacteria colonised 68% of '1 day' duration lesions and 79% of '3 day' duration lesions; staphylococci colonized 19% and 32% respectively and Pityrosporum spp. (Malassezia furfur) were found in 52% and 68%. Although the prevalence of each microbial group was higher in the more chronic lesions, these differences were not statistically significant. The microbial profile of inflamed lesions was similar both qualitatively and quantitatively to non-inflamed lesions studied previously. These results call into question the role of micro-organisms as the initiators of inflammation in acne vulgaris.