Are Cutibacterium acnes delivered from skin to deep tissues in primary reverse shoulder arthroplasty? A prospective study

Introduction: The objective of this study is to determine whether the deep tissues are inoculated during surgery with the Cutibacterium acnes still present in the skin after the surgical preparation in reverse shoulder arthroplasties.

Materials and methods: Prospective study including patients undergoing surgery with reverse shoulder arthroplasty. All the patients received preoperative antibiotic prophylaxis with cefazolin (2 g IV) and the skin was prepared with 2% chlorhexidine gluconate and 70% isopropyl alcohol. From all the patients, 9 cultures were obtained after the antibiotic was administrated and the skin surgically prepared. The cultures were sent to isolate C. acnes. DNA was extracted from the C. acnes isolated colonies. Isolate nucleotide distances were calculated using the Genome-based distance matrix calculator from the Enveomics collection toolbox.

Results: The study included 90 patients. C. acnes was isolated in 24 patients (26.6%) with a total of 61 positive cultures. There were 12 phylotype II, 27 IB and 22 IA. In 9 patients, C. acnes was present in both skin and deep tissues, and they constituted the sample to be studied by means of genomic analysis. In 7 out of the 9 patients, deep tissue samples clustered closer to at least one of its corresponding skin isolates when compared to the other independent bacterial ones.

Conclusions: The C. acnes present in the skin at the beginning of the surgery are the same as those found in the deep tissues at the end of the surgery. This result strengthens the possibility that the C. acnes is delivered from the skin to the deep tissues.