Risk Factors and Outcomes of Cutibacterium acnes Postoperative Central Nervous System Infection: A Case–Control Study

Objective: Cutibacterium acnes has emerged as a significant cause of postoperative central nervous system infections (PCNSIs). We sought to determine risk factors and outcomes associated with C. acnes PCNSI. Methods: This was a single-center 1:1 case-control study of patients with monobacterial C. acnes–associated PCNSI (cases) and unmatched controls with PCNSI caused by aerobic organisms. Patient and procedure-related characteristics were compared between groups. The main outcome was cure at 90 days after diagnosis. Mortality and neurologic disability were secondary outcomes. Results: We identified 13 patients with C. acnes PCNSI and 13 controls. All patients had postoperative intracranial abscess. Onset of infection was significantly later for cases versus controls (median and range, 22 [19–116] days and 15 [1–27] days, respectively; P = 0.002). Prolonged anaerobic incubation was required for C. acnes isolation (median, 8 days vs. 2 days for aerobic pathogens; P < 0.0001). The use of sealant and implants, fever at presentation, and white blood cell and C-reactive protein levels were similar between the 2 groups. All patients underwent surgical drainage. Patients received a median of 4 antibiotic drugs and 85 antibiotic days of treatment, with no significant between-group differences. Cure at 90 days was achieved for 10 patients (76.9%) with C. acnes PCNSI and 11 (84.6%) controls (P = 1.0). Conclusions: C. acnes PCNSI presents later than infection with aerobic bacteria but is associated with similar risk factors and clinical outcomes. These results underscore the importance of prolonged anaerobic incubation to optimize the recovery of C. acnes in the laboratory.