Propionibacterium acnes phylogenetic type III is strongly associated with progressive macular hypomelanosis. Propionibacterium acnes type III is associated with hypomelanosis

Progressive macular hypomelanosis (PMH) is a skin disorder that is characterized by hypo-pigmented macules distributed mainly on the trunk and usually seen in young adults. The cause of the disease is unknown, but the skin microbiota, in particular the bacterium Propionibacterium acnes, is suggested to play a role. Here, we compared the P. acnes population of PMH lesions with non-lesional skin of patients and matching controls of healthy individuals using an unbiased, culture-independent next-generation-sequencing approach. We also compared the P. acnes population before and after treatment with a combination of lymecycline and benzoylperoxide.We found a strong association of one subtype of P. acnes, type III, with PMH. This type is predominant in PMH lesions and adjacent skin areas in patients but rarely detected in matching control samples of healthy individuals. Strikingly, successful PMH treatment is able to alter the composition of the P. acnes population by substantially diminishing the proportion of P. acnes type III.Our study strongly suggests that P. acnes type III plays an important role in the formation of PMH. Furthermore, it sheds light on substantial differences in the P. acnes phylotype distribution between the upper and lower back and abdomen in healthy individuals.