The influence of various factors on the human resident skin flora.

Various factors, e.g. prolonged occlusion, skin disinfectants, systemic antimicrobials, can have an impact on the ecosystem of the normal human skin flora for a short time. These impacts are of clinical importance in the treatment of some skin diseases, where members of the normal human skin flora are involved in the pathogenesis of the disease, e.g. Propionibacterium acnes in acne vulgaris, Corynebacterium species in erythrasma, trichomycosis palmellina and pitted keratolysis, Pityrosporum orbiculare/ovale in Pityriasis versicolor, Pityrosporum folliculitis and others. Using the standardized forehead skin test, SFST, proposed by us, antibacterial short-term effects including the action degree profile, the action time profile, and the depth penetration profile of a topically applied antibacterial agent can be measured. Testing 60 v/v% isopropanol, 60 v/v% n-propanol, povidone iodine (aques solution), 3 w/v% salicylic acid in 50 v/v% isopropanol and 1 v/v% phenoli liquefacti in 50 v/v% isopropanol, salicylic acid showed equivalent reduction factors as 60 v/v% n-propanol immediately after the application. With the modified SFST, salicyclic acid tincture produced a 50-fold higher bacterial density reduction 12 hours after the fourth application and a 100-fold reduction 12 hours after the eighth application in comparison with 60 v/v% isopropanol. Salicylic acid, mainly used in dermatotherapy as a keratolytic agent, fulfills all these above mentioned requirements including a well antimicrobial efficacy. Since Salicyclic acid is also effective against yeast and dermatophytes, the substance has some advantages over other antimicrobials used in the dermatotherapy.