Debridement and retention of the prosthesis is a common surgical modality at our institution to treat prosthetic joint infection. Risk factors independently associated with treatment failure include the presence of a sinus tract and duration of symptoms prior to debridement of > or = 8 days.

Background. Culture-negative (CN) prosthetic joint infection (PJI) has not been well studied. We performed a retrospective cohort study to define the demographic characteristics and determine the outcome of patients with CN PJI.Methods. All cases of CN total hip arthroplasty and total knee arthroplasty infections (using a strict case definition) treated at our institution from January 1990 through December 1999 were analyzed. Kaplan-Meier survival methods were used to determine the cumulative probability of success.Results. Of 897 episodes of PJI during the study period, 60 (7%) occurred in patients for whom this was the initial episode of CN PJI. The median age of the cohort was 69 years (range, 36-87 years). Patients had received a prior course of antimicrobial therapy in 32 (53%) of 60 episodes. Of the 60 episodes, 34 (57%), 12 (20%), and 8 (13%) were treated with 2-stage exchange, debridement and retention, and permanent resection arthroplasty, respectively. The median duration of parenteral antimicrobial therapy was 28 days (range, 0-88 days). Forty-nine (82%) of 60 episodes were treated with a cephalosporin. The 5-year estimate of survival free of treatment failure was 94% (95% confidence interval, 85%-100%) for patients treated with 2-stage exchange and 71% (95% confidence interval, 44%-100%) for patients treated with debridement and retention.Conclusions. CN PJI occurs infrequently at our institution. Prior use of antimicrobial therapy is common among patients with CN PJI. CN PJI treated at our institution is associated with a rate of favorable outcome that is comparable to that associated with PJI due to known bacterial pathogens.

We determined the effect of methicillin resistance on the outcome of patients with Staphylococcus aureus prosthetic joint infections. From January 1995 to December 2004, 33% of 137 episodes of prosthetic joint infections were the result of S. aureus (in monomicrobial or polymicrobial cultures). Thirty-three (24%) episodes among 31 patients were the result of methicillin-susceptible S. aureus and 12 (9%) episodes among 12 patients were the result of methicillin-resistant S. aureus. Overall treatment failure rate was 38%. Patients with methicillin-susceptible S. aureus or methicillin-resistant S. aureus prosthetic joint infections did not differ in age, gender, comorbidities, joint age, prior surgical procedures performed on the affected joint, number of postsurgical medical complications, or duration of intravenous antimicrobial therapy. Patients with methicillin-resistant S. aureus prosthetic joint infection had longer hospital durations (median, 15 versus 10 days). Methicillin-resistant S. aureus in periprosthetic tissue culture resulted in a higher risk of treatment failure (hazard ratio, 9.2; 95% confidence interval, 2.40-35.46) than methicillin-susceptible S. aureus when controlling for joint location (total knee arthroplasty versus total hip arthroplasty [hazard ratio, 5.8; 95% confidence interval, 1.52-22.19]) and removal of hardware (hazard ratio, 0.24; 95% confidence interval, 0.077-0.75). Efforts should be made to prevent methicillin-resistant S. aureus infections of joint arthroplasties and develop new treatment modalities.

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Level III, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.