Blood Culture Flasks for Culturing Synovial Fluid in Prosthetic Joint Infections

149

Background While it is accepted accurate identification of infecting organisms is crucial in guiding treatment of periprosthetic joint infection (PJI), there remains no consensus regarding the best method for obtaining cultures. Questions/purposes We compared the yield of intraoperative tissue samples versus swab cultures in diagnosing PJI. Methods Tissue and swab cultures (three each) were collected prospectively during a consecutive series of 156 aseptic and septic revision arthroplasties from October 2011 to April 2012. The tissues and swabs were taken from standardized regions of the joint. After excluding 39 reimplantation procedures, we included 117 cases (74 hip, 43 knee; 30 septic, 87 aseptic) for analysis. We used a modified version of the Musculoskeletal Infection Society criteria for defining PJI, requiring three of five rather than four of six criteria. Tissue and swab cultures from septic and aseptic cases were used to calculate their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying PJI. Results Tissue cultures were positive in a higher percentage of septic cases than swab cultures: 28 of 30 (93%) versus 21 of 30 (70%). Tissue cultures were positive in two of 87 aseptic cases (2%), while swab cultures were positive in 10 of 87 (12%). The sensitivity, specificity, PPV, and NPV were 93%, 98%, 93%, and 98%, respectively, for tissue cultures and 70%, 89%, 68%, and 90%, respectively, for swab cultures. Conclusions Tissue cultures demonstrated higher sensitivity, specificity, PPV, and NPV for diagnosing PJI than swab cultures. Swab cultures had more false-negative and false-positive results than tissue cultures. Because swab cultures pose a higher risk of not identifying or incorrectly identifying infecting organisms in PJI, we believe their use in obtaining intraoperative culture specimens should be discouraged.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Swab Cultures Are Not As Effective As Tissue Cultures for Diagnosis of Periprosthetic Joint Infection

Aggarwal

Deirmengian

Parvızı

et al. 2013

149

“…However, the available tests for diagnosis of PJI are far from perfect. Cultures, for example, are negative in 7% to 12% of patients with PJI [5,10,16,19]. Culture-negative PJI can potentially complicate case classification and management and is an additional source of stress for both the patient and surgeon.…”

Section: Introductionmentioning

confidence: 99%

Premature Therapeutic Antimicrobial Treatments Can Compromise the Diagnosis of Late Periprosthetic Joint Infection

Shahi

Deirmengian

Higuera

et al. 2015

Background In the absence of positive cultures and draining sinuses, the diagnosis of periprosthetic joint infection (PJI) relies on laboratory values. It is unknown if administration of antibiotics within 2 weeks before diagnostic evaluations can affect these tests in patients with PJI. Questions/purposes The purpose of this study was to investigate the correlation of antibiotic administration with (1) fluctuations in the synovial fluid and serology laboratory values; and (2) sensitivity of the diagnostic tests in patients with late PJI (per Musculoskeletal Infection Society [MSIS] criteria). Methods Synovial white blood cell (WBC) count, polymorphonuclear neutrophil (PMN) percentage, and serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) as well as culture results were investigated in 161 patients undergoing total knee arthroplasty with late PJI diagnosed with the MSIS criteria. Depending on whether presampling antibiotics were used, patients were divided in two groups (53 [33%] patients were on antibiotics). The median laboratory values and the false-negative rates were compared between the two groups.

“…results. Although not clearly defined, multiple authors have reported rates of culture-negative periprosthetic infection of the hip and knee ranging from 7% to 12% [1,5,8,10,[16][17][18]. The chance that our results were affected by falsenegative culture results is somewhat offset by the fact that all 27 patients had two sets of cultures that were concordant; the aspirate cultures matched the intraoperative culture results for all patients (those who were infected and those who were not).…”

Section: Discussionmentioning

confidence: 85%

“…Stated otherwise, if the nucleated cell count is within normal limits, PJI can be ruled out; nucleated cell count could thus serve as an important screening test in patients where clinical suspicion of infection exists. However, the documented false-negative culture rate of 7% to 12% [1,5,8,10,[16][17][18] makes it difficult to exclude PJI based on this test alone. The false-negative rate of 0% in the current study is likely related to the limited sample size.…”

Section: Discussionmentioning

confidence: 99%

Are Nucleated Cell Counts Useful in the Diagnosis of Infection in Periprosthetic Fracture?

Preston

Somerville

Lanting

et al. 2015

Background Evaluating for the possibility of prosthetic joint infection in the setting of periprosthetic fracture is important because it determines the course of treatment. However, fracture-related inflammation can make investigations used in the diagnosis of infection less reliable. Questions/purposes The purpose of our study was to evaluate synovial fluid nucleated cell counts as a diagnostic test for deep prosthetic infection in patients with periprosthetic fractures around hip and knee arthroplasties. Specifically, we wished to determine the test's properties (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]) using threshold levels of nucleated cell counts as they are otherwise used in the diagnosis of periprosthetic infection. Methods Billing codes were used to identify all cases of revision total hip arthroplasty (THA), revision total knee arthroplasty (TKA), open reduction and internal fixation (ORIF) of the femur, and ORIF of the tibia at our institution between 2005 and 2013. A total of 2537 charts were identified and reviewed to reveal 269 patients with 269 periprosthetic fractures about a THA or TKA (10.6% of charts reviewed). Of these, 27 fractures in 27 patients (10% of the periprosthetic fractures identified) underwent aspiration of their total joint arthroplasty to rule out infection before surgical intervention. The decision to aspirate was made by the treating surgeon based on clinical suspicion of infection from the patient history, physical examination, and radiographic findings. Nucleated cell counts from joint aspirates were recorded for all 27 patients. Synovial fluid culture results were then used to calculate the sensitivity, specificity, PPV, and NPV of an elevated nucleated cell count in the diagnosis of infection. Results The specificity, sensitivity, PPV, and NPV of an elevated nucleated cell count in the diagnosis of infection were 64% (95% confidence interval [CI,.57]), 100% (95% CI, 19.29-100), 18% (95% CI, 2.37-45.46), and 100% (95% CI, 76.66-100), respectively. Eleven of 27 patients (41%) with joint aspirates had elevated nucleated cell counts. Only two of the 11 patients (18%) with elevated nucleated cell counts had positive synovial fluid cultures. None of the patients with normal nucleated cell counts had positive synovial fluid cultures. Conclusions Although quite common, an elevated nucleated cell count has moderate specificity and poor PPV in the diagnosis of infection in the setting of periprosthetic fracture. Level of Evidence Level IV, therapeutic study.