Cutibacterium acnes contamination does not enhance the proinflammatory profile of platelet concentrates.

Background: Cutibacterium acnes, a common anaerobic platelet concentrate (PC) contaminant, has been associated with rare mild adverse transfusion reactions and is often considered a harmless commensal. Notably, C. acnes can cause chronic infections and has been shown to induce the release of proinflammatory cytokines by immune cells. Since elevated concentrations of proinflammatory factors in PCs have been linked to noninfectious adverse reactions, this study aimed to assess whether C. acnes could elicit the release and accumulation of proinflammatory factors during PC storage, thereby enhancing the risk of such reactions. Study Design/Methods: Four ABO‐matched buffy coat PCs were pooled and split into six units, each were inoculated with either saline (negative control), a Staphylococcus aureus isolate (positive control, 30 colony forming units [CFU]/unit), or four C. acnes PC isolates (10 CFU/mL) and stored at 20–24°C with agitation. Bacterial counts, platelet activation, and concentration of proinflammatory factors were assessed on days 0, 3, and 5. N = 3. Results: C. acnes counts remained stable, while S. aureus proliferated reaching 108CFU/mL by the end of PC storage. By day 5, no significant differences in platelet activation or proinflammatory cytokine profiles were observed in C. acnes‐contaminated PCs compared to the negative control (p >.05), while there was a significant increase (p ≤.05) in sCD40L concentration (day 3), and platelet activation and IL‐8 concentration (day 5) in S. aureus‐contaminated units. Discussion: C. acnes contamination does not promote the accumulation of proinflammatory factors in the absence of proliferation during storage and may not enhance the risk of inflammatory reactions when transfused to patients. [ABSTRACT FROM AUTHOR]