Outcome of enterococcal prosthetic joint infection: is combination systemic therapy superior to monotherapy?

Background: The optimal medical or surgical therapy and outcome of enterococcal prosthetic joint infection are unknown.
Method: We performed a retrospective cohort study involving all patients with enterococcal total hip or knee arthroplasty infection treated at our institution from 1969 through 1999. The outcome for patients treated with combination systemic antimicrobial therapy (a cell wall-active agent and an aminoglycoside) versus monotherapy with a cell wall-active agent was analyzed.
Results: Fifty episodes of prosthetic joint infection due to enterococci occurred in 47 patients. The median duration of follow-up was 1253 days (range, 29-4610 days). The median age at the time of diagnosis was 70 years (range, 32-89 years). Fifty percent of episodes (25 of 50 episodes) occurred in male patients; 48% (24 of 50 episodes) involved total hip or knee arthroplasty. The estimate of 2-year survival free of treatment failure was 94% (95% confidence interval [CI], 83%-100%) for patients treated with 2-stage exchange, 76% (95% CI, 58%-100%) for patients treated with resection arthroplasty, and 80% (95% CI, 51.6%-100%) for patients treated with debridement and retention of the components (P=.9). The overall rate of 2-year survival free of treatment failure was 88% (95% CI, 77%-100%) for patients treated with monotherapy and 72% (95% CI, 54%-96%) for patients treated with combination therapy (P=.1). The development of cranial nerve VIII toxicity was significantly more common among patients receiving combination therapy (P=.002). Nephrotoxicity was more frequent in the combination therapy group (occurring in 26% of episodes; P=.09).
Conclusions: Enterococcal prosthetic joint infection is uncommon at our institution. Patients receiving combination therapy and those receiving monotherapy did not differ with respect to outcome. There were more cases of ototoxicity in the combination therapy group than there were in the monotherapy group.