Saturday, January 9, 2016

Propionibacterium - can it be eliminated in shoulder arthroplasty?

Propionibacterium acnes in primary shoulder arthroplasty: rates of colonization, patient risk factors, and efficacy of perioperative prophylaxis.

These authors sought to assess the rate of P. acnes colonization in patients undergoing primary shoulder arthroplasty, to identify patient-related risk factors, and to evaluate the efficacy of their perioperative antisepsis protocol. Within 30 minutes before the skin incision, 2 g of cefazolin and 3 mg/kg of gentamicin were infused intravenously. 

They obtained 4 superficial and 2 deep wound swabs in each of 30 patients undergoing primary shoulder arthroplasty (see chart). 

Cultures were observed for one week.

Twenty-two patients (73%) had positive cultures for P. acnes. 

Male gender (P = .024) and presence of hair >2.5 cm in length around the axilla, shoulder, upper back, chest, or neck on the operative side.(P = .005) had significantly higher rates of P. acnes superficial cultures. 

Subjects with positive superficial P. acnes cultures (P = .076) and presence of hair with a history of steroid injection (P = .092) were more likely to have deep P. acnes-positive cultures, but this was not statistically significant. 

They concluded that perioperative local antisepsis and cefazolin administration were not effective in eliminating P. acnes colonization.

Comment: This study indicates that Propionibacterium are unavoidably present in and around the arthroplasty surgical field and, as such, are positioned to establish a biofilm on the prosthetic joint surface and lead to a stealth-type periprosthetic infection.

In our practice, we use Ceftriaxone and Vancomycin IV prophylaxis in contrast to the cefazin used by these authors. We assume that every wound edge is leaking Propi and cover it with an antibiotic soaked sponge. We irrigate the wound copiously with Ceftriaxone and Vancomycin solution (3 liters). We use topical Vancomycin in the medullary canal and wound. We carefully avoid any contact between the prosthesis and the wound edge. And we pray that these methods will reduce the risk of the Propi problem. Only time and our careful followup will tell whether these efforts will prevent Propi from taking up residence on a prosthetic biofilm.