Drain fluid cultures can rule in but cannot rule out infection persistence after surgical treatment of periprosthetic joint infections.

BACKGROUND: Periprosthetic joint infection (PJI) is one of the most common reason for implant failure in arthroplasty. Surgical therapy is essential but there is no standardized guideline to determine infection eradication in multiple-step revision surgery. To date, clinical and laboratory inflammation markers and preoperative arthrocentesis are controversial to evaluate the infection status before reimplantation and therefore are often combined. Drain fluid cultures enable a microbiological analysis without need for further invasive procedure after revision surgery. This retrospective study evaluates the diagnostic performance of drain fluid cultures in diagnosing infection persistence according to the MSIS definition of PJI. METHODS: Drain samples have been taken after every revision surgery for microbiological testing. Afterwards, the results have been assigned to the infection status according to the diagnostic criteria of the MSIS definition of PJI. RESULTS: 1084 revision surgeries in 183 patients have been included, resulting in a total sample size of 1552 drain fluid cultures. Overall sensitivity was 36.0%, specificity was 90.7% and ROC-AUC was 0.63. CONCLUSION: Due to a high specificity and a low sensitivity drain fluid cultures can rule in but cannot rule out infection persistence in PJI.

Low Diagnostic Value of Synovial Aspiration Culture Prior to Reimplantation in Periprosthetic Joint Infection.

BACKGROUND/AIM: We aimed to determine the diagnostic value of the synovial aspiration culture prior to reimplantation in two- (or more) stage exchange of periprosthetic joint infection. PATIENTS AND METHODS: This was a retrospective study, spanning over ten years including all synovial cultures of patients with two- (or more) stage exchange due to periprosthetic joint infection. RESULTS: A total of 183 patients were included, mean age was 66.6 years (range=12.8-93.4 years). Overall sensitivity of synovial aspiration cultures before reimplantation was 56.6%, specificity 84.6%, negative predictive value (NPV) 63.8%, positive predictive value (PPV) 80.2%, area under the curve (AUC) 70.6%. Sensitivity of the knee in comparison to the hip culture was significantly higher, as well as the NPV and the AUC (p=0.038). In case of complete removal of prosthesis, the sensitivity and AUC were significantly reduced, whereas the specificity was comparable with prosthesis in situ, partial removal or complete removal. CONCLUSION: Due to the low sensitivity, obtaining several synovial cultures in the prosthesis-free interval to exclude persistence of infection, does not seem reasonable.