Propionibacterium

After its discovery in a patient with "acne vulgaris", Propionibacterium acnes, now called Cutibacterium acnes (see below Cutibacterium), underwent a series of taxonomic changes. It was successively placed in the genus Bacillus and then in the genus Corynebacterium. Later, this microorganism was shown to be more closely related to members of the genus Propionibacterium because, like other species of this genus, it ferments lactose to propionic acid in an anaerobic atmosphere. Recently, a major taxonomic revision has been proposed that places all Propionibacterium species from the skin microbiome into a new genus. Consequently, Propionibacterium is replaced by Cutibacterium (C.) e.g. C. avidum, C. acnes, C. granulosum and the recently discovered species C. namnetense and C. humerusii. The pathogenicity of these species has often been ignored, their existence considered as contamination in cultures.