Cutibacterium subtype distribution on the skin of primary and revision shoulder arthroplasty patients

The skin of healthy shoulders is known to harbor multiple different subtypes of Cutibacterium (formerly Propionibacterium) acnes at the same time. C acnes can often be isolated from deep tissue and explant samples obtained during revision of a failed shoulder arthroplasty, presumably because the shoulder was inoculated with organisms from the patient's skin at the time of the index arthroplasty. It is possible that specific subtypes or distributions of subtypes may be associated with an increased pathogenic potential and that the skin of patients undergoing revision arthroplasty contains different distributions of the subtypes than in patients undergoing primary arthroplasty. We analyzed the subtype distribution of Cutibacterium from the skin of shoulders undergoing revision arthroplasty vs. primary arthroplasty.

Preoperative skin swabs were collected from 25 patients who underwent primary shoulder arthroplasty and 27 patients who underwent revision shoulder arthroplasty. The results of semiquantitative cultures of the skin and deep tissues were reported as specimen Cutibacterium values, and scores from all deep tissue samples were added to report the total shoulder Cutibacterium score. Single-locus sequence typing (SLST) of C acnes from the skin swabs was used to determine the subtype distribution for each patient. The percentage of each subtype for each patient was averaged in patients undergoing revision arthroplasty and then compared with that in patients undergoing primary arthroplasty.

The C acnes subtype distribution on the skin of revision arthroplasty patients was different from that of primary shoulder arthroplasty patients, with a significantly higher percentage of SLST subtype A (36.9% vs. 16.0%, P = .0018). The distribution of SLST subtypes was similar between revision arthroplasty patients with strongly positive culture findings vs. those with weakly positive or negative culture findings.

Significant differences in the skin Cutibacterium subtype distributions were found between shoulders undergoing revision shoulder arthroplasty and those undergoing primary shoulder arthroplasty. Future studies are needed to determine whether certain Cutibacterium subtype distributions are associated with an increased risk of arthroplasty revision.