This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Background/Aim: Septic arthritis (SA) requires rapid diagnosis and therapy to avoid joint damage. This study evaluated the diagnostic accuracy of leukocyte esterase (LE) and glucose (GLC) strip tests for diagnosing SA. Patients and Methods: Synovial fluids from 455 patients with atraumatic joint effusions were assessed prospectively over a 5-year period with LE and glucose strip tests. Results were compared to modified Newman criteria for diagnosing joint infections. Synovial fluid cultures, crystal, blood and synovial cell analyses were also performed. Results: Fortyone patients had SA and 252 non-SA. A positive LE reading combined with negative glucose reading could detect SA with 100% specificity, 85% sensitivity, 100% positive predictive value (PPV) and 98% negative predictive value (NPV). Positive synovial LE reading alone detected SA with 82% specificity, 95% sensitivity, 47% PPV, and 99% NPV. Conclusion: Combined LE and glucose strip tests represent a low-cost tool for rapidly diagnosing or ruling out SA.Septic arthritis (SA) is a serious clinical condition that can result in permanent articular cartilage damage. SA is associated with considerable morbidity and mortality. To avoid disease progression, early and appropriate treatment is crucial. However, early SA assessments can be challenging, due to multiple differential diagnoses, including osteoarthritis and other inflammatory arthritides (e.g., crystal-induced diseases, like gout or chondrocalcinosis, or rheumatoid arthritis).Currently, clinicians distinguish between SA and other diagnoses with a variety of diagnostic tools, including synovial fluid cultures, Gram stains, synovial fluid analyses, and blood analyses. All these procedures have strengths and limitations. A synovial fluid culture is required for targeted antibiotic therapy, but it is time-consuming (incubations for at least 24 h) and its sensitivity is only 67%. Gram stains can deliver results rapidly, but they have a poor sensitivity (29-52%). Currently, synovial white blood cell (WBC) counts and the percentage of polymorphonuclear cells (%PMN) appear to be the most reliable diagnostic tests, and they provide results relatively quickly. Nevertheless, their limited availability in primary or secondary care settings constrains their usefulness for emergency situations. Moreover, these tests cannot reveal the causative pathogen. Consequently, new approaches are needed that provide rapid, accurate SA diagnoses.Previous studies have used colorimetric reagent strip tests, which are normally used to diagnose urinary tract infections, to identify infections in various body fluids, including pleural effusions, bronchoalveolar lavage fluid, peritoneal fluid, cerebrospinal fluid, and middle ear effusions. Those diagnoses were based on the presence of elevated leukocyte esterase (LE) levels. LE is produced by activated neutrophils recruited during inflammatory processes. Acute SA leads to a measurable increase in neutrophils, which leads to LE in synovial fluid.However, an LE examination would not di...

The diagnosis of periprosthetic infections (PJI) can be challenging in clinical practice because the clinical presentations of aseptic loosening and low-grade infections are similar. Semiquantitative evaluation of leukocyte esterase (LE) in synovial fluid using a urine strip test has already established itself as a diagnostic method over the past decade. The analysis of LE in synovial fluid leads to a high number of false-positive test results. In the present study, the value of a combined semiquantitative determination of glucose and LE in synovial fluid to improve the diagnosis of PJI was investigated. Over a 4-year period, 145 synovial samples were collected from patients who developed joint effusion after arthroplasty. LE and glucose test strips were considered as an index test for the diagnosis of PJI. A ++ or +++ LE and a negative glucose test strip reading were considered as positive test results. Modified diagnostic criteria for PJI as recommended by the Musculoskeletal Infection Society (MSIS) served as the reference test, except that intraoperative findings were excluded. Forty-six out of 145 samples were classified as septic complication according to the reference test. In regard to PJI, our data showed that combined use of LE and glucose strip test reading displayed a 98.0% specificity (95% confidence interval (CI): 95.2% to 100%), a 50% sensitivity (95% CI: 35.6% to 64.4%), a 92% positive predictive value (95% CI: 81.4% to 100.0%), and an 80.3% negative predictive value (95% CI: 73.2% to 87.4%). In contrast, the exclusive analysis of LE on the urine strip to diagnose PJI demonstrated a 90.9% specificity (95% CI: 85.2% to 96.6%), a 67.4% sensitivity (95% CI: 53.8% to 80.9%), a 77.5% positive predictive value (95% CI: 64.6% to 90.4%), and an 85.7% negative predictive value (5% CI: 79.0% to 92.4%). A combination of LE and glucose test pad reading is considered superior as a potential “rule-in” method for the diagnosis of PJI compared with LE test pad analysis alone. However, combined LE and glucose synovial fluid testing also demonstrated lower test sensitivity and thus diagnostic accuracy compared with LE analysis alone. Therefore, combined glucose and LE test pad analysis does not represent a sufficient diagnostic standard to exclude PJI with certainty.