Periprosthetic Infections of the Shoulder

Diagnosis and Management

E. Scott Paxton, MD; Andrew Green, MD; Van S. Krueger, MD, MBA

Disclosures

J Am Acad Orthop Surg. 2019;27(21):e935-e944. 

In This Article

Microbiology

The most common bacteria isolated in PJIS is Cutibacterium acnes (formerly Propionibacterium acnes), likely due to the high colonization rate of the skin and dermis of the shoulder girdle.[5–7] This differs from hip and knee PJI where Staphylococcus aureus, Staphylococcus epidermidis, and coagulase-negative Staphylococcus (CNS) are the most common causative organisms.

C acnes is a slow-growing, gram-positive, facultative anaerobic rod primarily residing in the sebaceous glands of hair follicles within the deep dermis. It forms a biofilm that isolates the organisms from the host defense mechanisms, making detection and complete eradication difficult.[8] Based on the recent findings of gene sequencing, C acnes was reclassified as C acnes.[9] In this review, it is referred to as C acnes. Multiple phenotypes of C acnes are identified with different degrees of pathogenicity, with some evidence of a relation to hemolytic properties, and antibiotic resistance, mainly to clindamycin.

Interestingly, C acnes has been cultured from the shoulders during primary arthroscopic and open surgery. It remains to be seen whether these findings represent culture contamination, deep tissue contamination with organisms from the subdermis, or even evidence of primary deep infection that may be a cause of glenohumeral arthritis.[10,11] In addition, some of these studies report control cultures that are positive for the bacteria.[12]

Although C acnes is the most common causative microorganism (38.9% of cases), other bacteria including S aureus (14.8%), S epidermidis (14.0%), and CNS (not otherwise specified) (14.0%) are also isolated (Table 1).

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....