Cutibacterium is the pathogen most commonly isolated from periprosthetic infections of the shoulder. Because Cutibacterium is found in the dermis of normal shoulder skin, the skin incision for arthroplasty can introduce the bacteria into the shoulder wound where it can cause an infection.
We've learned that certain patient characteristics are associated with increased risk for Cutibacterium periprosthetic infections of the shoulder, including young age, male sex, use of testosterone supplements, increased serum testosterone levels and increased loads of Cutibacterium on preoperative cultures of the unprepared shoulder skin.
We recently posted on the use of topical Betadine to reduce the load of Cutibacterium in open shoulder surgery (see this link).
Last year a review article concluded that home skin-disinfection using benzoyl peroxide (BPO) was more effective than chlorhexidine in reducing the rate of positive Cutibacterium cultures on the skin surface but that neither completely eliminated Cutibacterium from the field (see this link).
Last month our colleagues in Linköping, Sweden published an excellent randomized trial, Benzoyl peroxide treatment decreases Cutibacterium acnes in shoulder surgery, from skin incision until wound closure. They examined the effect of benzoyl peroxide (BPO) topically applied to the skin of the shoulder on bacterial colonization in 100 patients having elective shoulder surgery, randomizing the patients to preoperatively prepare their planned incisional area with either BPO or with soap (control group).
Four skin swabs were taken in a standardized manner at different times, before and after surgical skin preparation, 1 in dermis, and finally after the skin was sutured. Before skin incision, 5 punch biopsies were retrieved spaced 2 cm apart in the planned skin incision.
Quantification of Cutibacterium was obtained by serial dilutions.
Treatment with BPO considerably lowered the amount of Cutibacterium compared to the control group. The positive effect of BPO persisted until skin closure, at which time some recolonization of Cutibacterium had occurred.
They found that men had a 5-fold higher amount of Cutibacterium on untreated skin.
Five patients in the study were subsequently treated for early deep surgical site infections with surgical debridement, deep tissue cultures, and antibiotics.
Three were from the BPO group (1 woman and 2 men) and 2 men from the control group. Deep cultures from the BPO group cases detected Staphylococcus aureus in 2 and a mixture of S epidermidis and C
acnes in the third.
Two were from the control group had a growth of Cutibacterium only.
Comment: For the shoulder surgeons and patients that have had to deal with the risk of Cutibacterium periprosthetic infections, data supporting interventions to minimize this risk are most needed and welcome.
Evidence is mounting that intraoperative application of Betadine is effective. Other treatments, such as topical Vancomycin and a course of post operative antibiotics are in common use, but as yet do not have rigorous data to support them. Other preventative steps include avoiding contact of implants with the cut dermal edge and handling the implant with fresh gloves. Taken together these steps are not costly in comparison to the cost and loss of comfort and function associated with a Cutibacterium infection. Even with these steps, the risk of Cutibacterium PJI cannot be completely eliminated; however, risk reduction is surely worth the effort.
This study points to the effectiveness of the preoperative application of BPO to the skin in the area of the planned arthroplasty incision in reducing the levels of Cutibacterium in the arthroplasty wound, but that this effect is no longer significant at the time of wound closure.
Reducing the levels of Cutibacterium seems like a good thing, however, it is a potential concern that there were three early deep surgical site infections in the group receiving BPO and an even greater concern that three of these were infections from Staphylococcus (2 aureus and 1 epidermidis). Infections from Staphylococcus (especially aureus) are rare in the shoulder. This causes us to wonder if Cutibacterium is more Jekyll or Hyde (see this link). It would be unfortunate to lower the risk of Cutibacterium while increasing the rate of Staph.
We can be sure to learn more from future clinical research on this critical topic.
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