[Differentiation of various Propionibacterium species from acne-vulgaris efflorescences]

Samples of pustules taken from 37 patients with acne (a. vulgaris, a. papulopustulosa, a. conglobata) were examined using different culture mediums for the growth of anaerobic to microaerophilic coryneforms. We identified 46 isolates of Propionibacteria which were tested according to their morphological, biochemical, serological, and phagelysotopic reactions. Three types of Propionibacteria were found: P. acnes (33), P. granulosum (11) and P. avidum (2). Nine samples showed P. acnes combined with P. avidum, four samples from patients with acne conglobata showed P. granulosum or P. avidum only. Tests from 37 patients are too limited to reach definite conclusions. We are not able to suggest any correlation between type and degree of clinical acne, and the isolated Propionibacteria. These data indicate that pustules from patients with acne of all clinical degrees can contain P. acnes as well as other anaerobic coryneforms. Therefore, other species of anaerobic bacteria, particularly those of the "propionibacteria type", should be included in any discussion about the aetiological factors of acne.