THE SHORT-TERM TREATMENT OF ACNE-VULGARIS WITH BENZOYL PEROXIDE - EFFECTS ON THE SURFACE AND FOLLICULAR CUTANEOUS MICROFLORA

A 28-day treatment regimen was undertaken by 12 volunteers, in which 5 % (w/v) benzoyl peroxide (BP) in an aqueous gel was applied daily to t he entire face. Clinical efficacy of the treatment was assessed after 2, 4, 9, 14 and 28 days, and the surface and follicular microbial popu lations were enumerated using established techniques. Viable counts we re obtained for propionibacteria and Micrococcaceae. Mean numbers of p ropionibacteria recovered from the skin surface and follicular casts w ere significantly reduced after 2 days' treatment (P<0.01), and the po pulation was maintained at a significantly lower level throughout the study (P<0.01), with mean values approaching the lower detection limit of the assay. Significant reductions in the surface and follicular Mi crococcaceae were observed after 2 days' treatment, and at all subsequ ent visits (P<0.05). After 2 days' treatment, only slight reductions i n mean acne grade and mean inflamed lesion count were observed. Howeve r, at all subsequent visits the mean acne grade was significantly redu ced (P<0.05) compared with T-0. The mean non-inflamed lesion count was lower than the pretreatment level at all visits, although the results were variable. The results indicate that significant reductions in su rface and follicular microorganisms may be obtained after 48 h treatme nt with BP. Therefore, the non-specific antibacterial action of BP may be utilized in short intervening courses to reduce the carriage of an tibiotic-resistant micro-organisms and thus improve the long-term effi cacy of antibiotic acne treatments. The speed of clinical improvement may be limited by the rate at which old lesions disappear, rather than the effectiveness of the treatment in preventing new lesions arising.