Delayed infection of a total shoulder with Propionibacterium acnes (P. Acnes)

A 66-year-old man had a total shoulder performed elsewhere in 2005 with an excellent functional result until seven years later when he presented with a three-month history of a stiff, uncomfortable shoulder. Clinical evaluation was unremarkable except for limited range of shoulder motion. All laboratory studies were normal. Radiographs (shown below) suggested glenoid component failure. 

At surgery, we found the shoulder to be scarred throughout. The glenoid component was loose and the glenoid bone had undergone osteolysis. The humeral component was well fixed, but there was osteolysis about the proximal stem. Even though there was no evidence of acute inflammation our revision protocol calls for multiple cultures before antibiotics are administered, including explants and several tissue samples. The glenoid was removed and the vault debrided. An extensive soft tissue release was performed. The osteolytic areas of the humerus were debrided and the head component exchanged. The patient was treated initially with empiric intravenous Vancomycin and oral rifampin. Once his cultures returned (results shown below), we converted him to ceftriaxone 2 grams IV every 24 hours plus rifampin 600 mg by mouth every 24 hours. After six weeks, we plan to convert him to oral Augmentin. Clinically he is much improved from his preoperative condition, is off pain medication and maintaining over 150 degrees of motion.

Nine specimens were obtained for culture each in (1) aerobic: Trypticase Soy Agar with 5% sheep blood, chocolate agar (AER), (2) broth: brain-heart infusion (BHI), and (3) anaerobic: Brucella Agar (with blood, hemin and vitamin K) (BRU).

The results of these cultures were as follows

Specimen source	AER days to +	BHI days to +	BRU days to +
Fluid	No growth	9	8
Glenoid explant	5	9	4
Glenoid Membrane	No growth	9	8
Glenoid membrane	7	9	8
Humeral head explant	No growth	No growth	17
Humeral membrane	No growth	9	8
Humeral membrane	No growth	9	8
Humeral membrane	8	9	No growth
Humeral membrane	No growth	9	8

These results indicate that holding cultures for a few days or a week would result in overlooking many of the positive cultures. While some of these results are consistent with each other, some are different, indicating that multiple cultures using multiple media may be of value in securing the diagnosis.

----


If you have suggestions for topics you'd like us to address in this blog, please send an email to
shoulderarthritis@uw.edu

Use the "Search the Blog" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery.

See the countries from which our readers come on this post.