A comparative study of Cutibacterium (Propionibacterium) acnes clones from acne patients and healthy controls

•Sebaceous follicles from facial acne are frequently dominated by C. acnes of clade I -1a CC18.•Genomes of CC18 isolates from acne patients and healthy controls were highly conserved.•CC18 showed no differences in health or disease associated virulence or protective genes or in regulatory sequence elements.•CC18 appear to possess properties for growth in acne-affected sebaceous follicles and may induce acne in susceptible hosts.

BackgroundCutibacterium (Propionibacterium) acnes is assumed to play an important role in the pathogenesis of acne.ObjectivesTo examine if clones with distinct virulence properties are associated with acne.MethodsMultiple C. acnes isolates from follicles and surface skin of patients with moderate to severe acne and healthy controls were characterized by multilocus sequence typing. To determine if CC18 isolates from acne patients differ from those of controls in the possession of virulence genes or lack of genes conducive to a harmonious coexistence the full genomes of dominating CC18 follicular clones from six patients and five controls were sequenced.ResultsIndividuals carried one to ten clones simultaneously. The dominating C. acnes clones in follicles from acne patients were exclusively from the phylogenetic clade I-1a and all belonged to clonal complex CC18 with the exception of one patient dominated by the worldwide-disseminated and often antibiotic resistant clone ST3. The clonal composition of healthy follicles showed a more heterogeneous pattern with follicles dominated by clones representing the phylogenetic clades I-1a, I-1b, I-2 and II.Comparison of follicular CC18 gene contents, allelic versions of putative virulence genes and their promoter regions, and 54 variable-length intragenic and inter-genic homopolymeric tracts showed extensive conservation and no difference associated with the clinical origin of isolates.ConclusionsThe study supports that C. acnes strains from clonal complex CC18 and the often antibiotic resistant clone ST3 are associated with acne and suggests that susceptibility of the host rather than differences within these clones may determine the clinical outcome of colonization.