In this work it was demonstrated that the main microorganisms which cause, together with other, the generation of inflammatory changes are anaerobic bacteria from the genus Propionibacterium. P. acnes type I causes mild course acne changes while serious changes are generated by P. granulosum type II. It was observed that a high percentage of all tested Propionibacterium strains showed susceptibility to antibiotics but it did not reach 100%. In the treatment of acne changes all agents which could be conducive to generating them should be taken into consideration. The therapy should be complex and applied with regard to the course of disease of each individual patient.