Propionibacterium acnes types I and II represent phylogenetically distinct groups.

Area of Science:

• Microbiology
• Molecular Biology
• Infectious Diseases

Background:

• Two phenotypes of Propionibacterium acnes (P. acnes), types I and II, are known, but their epidemiological roles in infections are understudied.
• P. acnes is an opportunistic pathogen implicated in various infections, including prosthetic joint infections and acne.

Purpose of the Study:

• To investigate the prevalence of P. acnes types I and II in different clinical isolates.
• To determine if phenotypic differences correlate with genotypic and phylogenetic distinctions.
• To evaluate nucleotide sequencing as a method for P. acnes type identification.

Main Methods:

• Immunofluorescence microscopy using monoclonal antibodies (MAbs) QUBPa1 and QUBPa2 to differentiate P. acnes types I and II.
• Analysis of 132 P. acnes isolates from various sources: prosthetic hip implants, bone, tissue, acne, dental infections, and surgical skin.
• Phylogenetic analysis using nucleotide sequencing of the 16S rRNA gene, recA, and a putative hemolysin gene (tly).

Main Results:

• Isolates from prosthetic hip implants showed roughly equal proportions of type I and II.
• Isolates from acne, dental infections, surgical skin, and bone/tissue samples were predominantly type I.
• Nucleotide sequencing of recA and tly genes revealed type-specific polymorphisms, supporting distinct phylogenetic clusters for types I and II. Eleven atypical isolates were identified as type I by sequencing, with nine forming a distinct subcluster within type I.

Conclusions:

• Phenotypic differences between P. acnes types I and II are underpinned by significant phylogenetic distinctions.
• Nucleotide sequencing of recA and tly genes is a reliable method for P. acnes type identification and phylogenetic analysis.
• Evidence suggests a further phylogenetic subdivision within P. acnes type I.