Reclassification of Propionibacterium acnes

The bacterium Propionibacterium acnes has been reclassified as Cutibacterium acnes, based on discrepancies between the phylogenetic signals of 16S rRNA gene sequence analysis and high-resolution core-genome analysis.

The former P. acnes is a bacterium associated with the outer layers of the human skin and it has an association with sterility test failures. 

The reference for the change is:

Scholz, C.F.P. and Kilian, M. (2016) The natural history of cutaneous propionibacteria, and reclassification of selected species within the genus Propionibacterium to the proposed novel genera Acidipropionibacterium gen. nov., Cutibacterium gen. nov. and Pseudopropionibacterium gen. nov., International Journal of Systematic and Evolutionary Microbiology, 66, 4422–4432

Here is the abstract to the paper:

The genus Propionibacterium in the family Propionibacteriaceae consists of species of various habitats, including mature cheese, cattle rumen and human skin. Traditionally, these species have been grouped as either classical or cutaneous propionibacteria based on characteristic phenotypes and source of isolation. To re-evaluate the taxonomy of the family and to elucidate the interspecies relatedness we compared 162 public whole-genome sequences of strains representing species of the family Propionibacteriaceae. We found substantial discrepancies between the phylogenetic signals of 16S rRNA gene sequence analysis and our high-resolution core-genome analysis. To accommodate these discrepancies, and to address the long-standing issue of the taxonomically problematic Propionibacterium propionicum, we propose three novel genera, Acidipropionibacterium gen. nov., Cutibacterium gen. nov. and Pseudopropionibacterium gen. nov., and an amended description of the genus Propionibacterium. Furthermore, our genome-based analyses support the amounting evidence that the subdivision of Propionibacterium freudenreichii into subspecies is not warranted. Our proposals are supported by phylogenetic analyses, DNA G+C content, peptidoglycan composition and patterns of the gene losses and acquisitions in the cutaneous propionibacteria during their adaptation to the human host.

The paper can be found online here.

Posted by Dr. Tim Sandle