Leukocyte Esterase as a Biomarker in the Diagnosis of Periprosthetic Joint Infection

Abstract

BackgroundTotal joint arthroplasty (TJA) has been one of the most rewarding interventions for treating patients suffering from joint disorders. However, periprosthetic joint infection (PJI) is a serious complication that frequently accompanies TJA. Our study aimed to investigate the application of the leukocyte esterase (LE) strip in the diagnosis of PJI.Material/MethodsFrom October 2014 to July 2015, 72 patients who had undergone joint puncture after arthroplasty in our hospital were enrolled in this trial. One drop of synovial fluid from each available patient was applied to the LE strip, and the results were observed after 1–3 min. If the color turned to dark purple, we recognized this as a positive result, while other colors were regarded as negative results. Centrifugation was used when the synovial fluid was mixed with blood. The Musculoskeletal Infection Society (MSIS) definition was used as the standard reference to identify whether PJI was found in patients or not. The results of diagnosis and LE strips test were compared, and indicators reflecting diagnostic value were calculated. Correlation of the LE data with erythrocyte sedimentation rate (ESR), elevated C-reactive protein (CRP), synovial white blood cell (WBC) counts, and polymorphonuclear neutrophil (PMN) percentage was calculated.ResultsBy MSIS criteria, 38 patients were diagnosed with PJI and 34 patients were not infected. Two types of LE strip presented the same results with sensitivity of 84.21% (95% confidence interval [CI]: 68.75~93.98%), specificity of 97.06% (95% CI: 84.67~99.93%), positive predictive value (PPV) of 96.97% (95% CI: 84.24~99.92%), and negative predictive value (NPV) of 84.62% (95% CI: 69.47~94.14%). There were one false-positive case and six false-negative cases in this trial. There is a strong correlation between LE strip and synovial fluid PMN percentage.ConclusionsThe sensitivity and specificity of the LE strip in the diagnosis of PJI are quite high, which means the LE strip might be used as an alternative to diagnose PJI in clinical practice.

The Leukocyte Esterase Test Strip Is a Poor Rule-Out Test for Periprosthetic Joint Infection

“…The original report on the utility of LE by Parvizi et al [6] found that a (þþ) LE cutoff provided 80.6% sensitivity in diagnosing PJI. Although there are a few centers reporting a higher sensitivity for the urinary LE test strip [10,11], most centers have reported lower values, including sensitivities of 69% [5], 66% [9], 81% [1], 84.21% [2], 75% [3], and 84% [4]. A recent large retrospective study of tests for PJI including the erythrocyte sedimentation rate, C-reactive protein, WBC count, polymorphonuclear neutrophil percentage, and LE found that LE had the lowest sensitivity of all tests [3].…”

“…Despite demonstrating urinary LE test strip sensitivities ranging from 69%-84%, previous studies [1,2,6,9] have suggested enthusiasm regarding the utility of the test strip for diagnosing PJI. In fact, one study demonstrating a test strip sensitivity of 81% suggested that a negative urinary LE test strip result may rule-out PJI with no need for further testing [1].…”

Alpha-Defensin versus Leukocyte Esterase in Periprosthetic Joint Infection: An Updated Meta-Analysis

“…Meanwhile, seventeen studies involving a total of 1963 patients (571 joints with PJI) explored the diagnostic accuracy of leukocyte esterase for PJI [ 14 , 16 , 21 , 22 , 26 , 28 , 31 , 32 , 36 , 39 , 40 , 42 – 44 , 47 , 50 , 51 ]. All studies used the standard chemical test strip, among which two studies [ 16 , 32 ] used an automated reader to define the final result while thirteen studies [ 14 , 21 , 22 , 26 , 28 , 31 , 36 , 39 , 40 , 42 – 44 , 47 , 50 , 51 ] used the naked eye. The mean ages of included patients ranged from 60.3 to 71.0 years, and the proportion of males ranged from 21.7% to 60.9%.…”

What’s New in Musculoskeletal Infection: Update on Biofilms

“…When sampling tissue, 3 to 4 tissue samples should be obtained when treating PJI to facilitate organism identification and antimicrobial management, in the experience of 2 institutions 42,43 . Markers for PJI that were studied include presepsin 44 , adenosine deaminase 45 , procalcitonin 46,47 , interleukin-6 (IL-6) 48 , leukocyte esterase [49][50][51][52] , alpha-defensin [53][54][55] , D-dimer 56 , receptor activator of nuclear factor-kB ligand (RANKL), and osteoprotegerin 57 . Centrifugation of synovial fluid samples at 2,000 · gravity for 15 minutes improves leukocyte esterase testing, but testing should be performed on the top 2 mm of the centrifuged sample 58 .…”