GENOMIC CHARACTERIZATION AND CLINICAL EVALUATION OF PERIPROSTHETIC JOINT INFECTIONS CAUSED BY <i>CUTIBACTERIUM ACNES</i>

Aim Cutibacterium acnes is a major skin commensal that may also act as an opportunistic pathogen. Findings of C. acnes in tissue cultures obtained during arthroplasty revision surgery are difficult to interpret, since they may represent true infection or contamination. This study investigated whether C. acnes isolates obtained from prosthetic joint infections (PJIs) were related and shared common genomic traits that might correlate with clinical courses and patient outcomes. Method C. acnes isolates from revision surgery of patients with PJIs of the hip, shoulder, and knee were characterized using molecular methods to determine sequence type (ST) and the presence of virulence determinants (CAMP factors, dermatan sulfate-binding adhesion 1, hyaluronidase lyase, and linear plasmid). A standardized review of the patients’ medical charts was performed. Results The study included 37 patients with C. acnes culture-positive tissue samples where multiple isolates of C. acnes belonged to the same ST. Most of the isolates belonged to phylotype IA 1 . Phylogenetic analysis of virulence determinants revealed no shared pattern among PJI isolates. Seven patients had a polymicrobial infection. Exchange revision was performed in 70% of the patients, and &gt;50% of all patients received antibiotic treatment for ≥3 months. Failure was noted in seven patients, all of whom had shoulder PJIs. Conclusions No specific ST or any identifiable unique feature among virulence determinants were found among C. acnes isolated from PJIs of hips and shoulders. The majority of all included patients had low inflammatory markers and were treated successfully, even when the infection consisted of a polymicrobial infection.