A 7-year retrospective review from 2005 to 2011 of Propionibacterium acnes shoulder infections in Ottawa, Ontario, Canada.

This study evaluated the clinical factors associated with Propionibacterium acnes shoulder infection and the standard culture procedures for isolating P. acnes from shoulder specimens by a 7-year retrospective analysis. P. acnes was incriminated as the second most common pathogen in 17 of 80 patients with positive shoulder cultures. All of the 17 patients had prior shoulder implant. The cumulative rates for isolating P. acnes were 1.9%, 1.9%, 41.9%, 96.4%, and 100% at day 1 to day 5 of incubation, respectively. The standard practice of anaerobic culture was able to detect P. acnes from shoulder specimens in patients with a clinical suspicion of infection. The sensitivity and specificity of prolonged incubation remain to be determined.