Shoulder periprosthetic joint infection caused by Propionibacterium acnes

Abstract

Propionibacterium acnes is increasingly recognized as an important cause of shoulder periprosthetic joint infection (PJI). We performed a retrospective cohort study of P. acnes shoulder PJI to analyze the clinical, diagnostic, and treatment characteristics. Patients diagnosed with shoulder PJI caused by P. acnes were retrospectively analyzed in two university hospitals. Patient data were retrieved through chart review. The outcome was evaluated at patient follow-up visits. The study included 20 patients with shoulder PJI (median age, 65 years; range, 54–77 years); 75 % were males. The median time from prosthesis implantation to diagnosis of PJI was 34 months (range, 2–60 months). Most PJI (55 %) were diagnosed >24 months after arthroplasty, followed by delayed manifestation 3–24 months after arthroplasty in 30 %. The diagnosis of PJI was preoperatively confirmed in 50 % of patients and suspected in 20 %. Persistent pain was present in 90 %, local signs of inflammation in 60 %, and radiological signs of loosening in 70 % of patients. P. acnes was cultured in joint aspirate in 33 %, periprosthetic tissue in 60 %, and sonication fluid in 89 % of patients. In four patients, coinfection with coagulase-negative staphylococci was found. One-stage prosthesis exchange was performed in four patients (20 %) and two-stage exchange in 15 patients (75 %); in one patient the prosthesis was not re-implanted. After a median follow-up of 26 months (range, 12–47 months), 18 patients (90 %) showed no signs or symptoms of infection. P. acnes PJI typically manifested several years after implantation. In 30 % of patients, PJI was not suspected before surgery. In patients with persistent pain or prosthesis loosening, low-grade PJI should be excluded, including infection caused by P. acnes.