Effect of topical application of dexamethasone on Propionibacteria in the pilosebaceous duct.

A preparation of dexamethasone 0.02% in Eutanol G (n octyldodecanol) was applied once daily for three weeks, to the right side of the forehead of 25 male healthy test subjects. Eutanol G without dexamethasone was applied in the same way to the left side of the forehead. Before and at the end of the treatment period bacteria were removed from the pilo-sebaceous ducts by the method of Holland et al. [8]. Bacteria that grew under anaerobic conditions were evaluated quantitatively. Dexamethasone induced a significant increase in P. acnes, in all Propionibacteria and in the total bacterial count. The importance of these findings is discussed in relation to the development of steroid acne.