According to an abstract of an October 2008 article that appeared in the Journal of Clinical Microbiology, current clinical and microbiological information has not demonstrated a clear connection between Propionibacterium acnes and acne. Thus, in order to determine whether acne could be associated with as-of-yet uncultured bacteria residing in diseased skin follicles, researchers at Aarhus University, Denmark, conducted sequencing and phylogenetic analyses of approximately 5,700 amplified and cloned 16S rRNA genes to determine the bacterial diversity in follicles from acne patients and healthy individuals, and from the superficial skin of acne patients.
It was found that follicles from healthy skin were exclusively colonized by P. acnes, whereas the follicular bacteria of acne patients included, in addition to P. acnes, Staphylococcus epidermidis and minute amounts of other species. In contrast, samples from superficial skin showed a complex of 12 to 16 bacterial species.
The findings of this study exclude the possibility that acne is associated with yet-uncultured bacteria, and shows that healthy skin follicles constitute an exclusive habitat allowing the colonization of only P. acnes.