Analysis of distribution patterns of Propionibacterium acnes phylotypes and Peptostreptococcus species from acne lesions

Summary Background The precise roles of Propionibacterium acnes and other anaerobic bacteria in the pathogenesis of acne are still unclear. Recent studies have shown that P. acnes can be further classified into several phylotypes with distinct phenotypes and virulence. Their distribution patterns in acne lesions have rarely been demonstrated. Objectives To analyse distribution patterns of P. acnes phylotypes and Peptostreptococcus species on the skin surface of patients with acne and healthy controls, and in comedones, papules and pustules from patients. Methods A total of 370 samples from 95 patients with acne and 65 samples from 65 healthy controls were investigated. Three P. acnes phylotypes and three Peptostreptococcus species were identified by polymerase chain reaction primarily using type‐specific primers. Results There was no significant difference in the microflora of the skin surface samples between patients with acne and healthy controls. In acne lesions, distribution patterns between skin surface and comedonal lesions were similar, but they were significantly different from those of both papules and pustules. In the inflammatory acne lesions, the proportion of type IA P. acnes was increased, while those of type IB and II were decreased. The proportion of Peptostreptococcus species was also increased significantly in the inflammatory lesions. Conclusions At the precision of this qualitative study, our results do not provide any evidence that different phylotypes in the surface microflora might be important in triggering acne. However, type IA P. acnes and Peptostreptococcus species might be more closely associated with inflammatory acne lesions. What's already known about this topic? The precise roles of Propionibacterium acnes and other anaerobic bacteria in the pathogenesis of acne are still unclear. Recent studies have shown that P. acnes can be classified into several phylotypes with distinct phenotypes and virulence; their distribution patterns in acne samples have rarely been demonstrated. It is suspected that anaerobic organisms other than P. acnes also have a role in the pathogenesis of acne. What does this study add? There was no significant difference in the microflora of the skin surface samples from the acne and non‐acne groups. Type IA P. acnes and Peptostreptococcus species were found in higher proportions in papules and pustules compared with comedones and the skin surface, suggesting their possible association with inflammatory l