UW Shoulder and Elbow Academy: Propionibacterium in revision shoulder arthroplasty.

The challenge of Propionibacterium acnes and revision shoulder arthroplasty: a review of current diagnostic options.

These authors reviewed the literature on the demographic, clinical, and radiographic predictors of P. acnes infection and review the current options for diagnosis.

Of the techniques reviewed, α-defensin had the highest sensitivity in detecting P. acnes infection but this sensitivity was just a bit better than 50-50 (63%). Traditional inflammatory markers, such as C-reactive protein level and erythrocyte sedimentation rate were often normal in cases of infection.

Comment: We have found that even with all the new "molecular" methods being proposed, one of the best indicators of a possible Propionibacterium-positive failed shoulder arthroplasty is the history of an initially good result (the honeymoon period) followed by the delayed onset of pain and stiffness without an alternative explanation. Concern is particularly high when this scenario presents in the context of an active, relatively young male patient who has had prior surgeries.

While the authors state that tissue culture is the “gold standard” for the diagnosis, like everything else, cultures need to be done in a way that assures the maximal yield, as described here, with at least five tissue or explant specimens, cultured on aerobic and anaerobic media and observed for 17 days. Fluid aspirates are not a high yield specimen source for Propionibacterium. Finally, even with an optimal approach to diagnosis, the presence of Propionibacterium cannot be ruled outs because like truffles they are unlikely to be numerous and they are unevenly distributed throughout the area.