Contribution to the interpretation of the occurrence of unsuccessful therapeutical results in acne vulgaris with topical erythromycin (Propionibact. acnes).

Investigations are reported which attempt to contribute towards an understanding of those cases in which topical treatment with erythromycin is unsuccessful. In 13 acne patients no resistance of P. acnes was observed after seven weeks of topical treatment with erythromycin. This demonstrates that the 20% frequency of resistance induction reported in the literature is too high. In the 13 treated patients there was no essential reduction in the number of inflammatory lesions although a decrease in the number of Propionibacteria in the pilosebaceous ducts occurred. This result is perhaps connected with a concurrent increase in Micrococcaceae, which could suggest that not only Propionibacteria, but also Micrococcaceae play a role in the pathogenesis of acne.