Leukocyte Esterase and Glucose Reagent Test Can Rule in and Rule out Septic Arthritis

Abstract

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...

Diagnostic Accuracy for Periprosthetic Joint Infection Does Not Improve by a Combined Use of Glucose and Leukocyte Esterase Strip Reading as Diagnostic Parameters

“…Omar et al, were among the first to investigate the joint evaluation of LE and glucose with the reagent strip test as a diagnostic approach for the diagnosis of SA. In contrast to our data, the authors reported that simultaneous measurement of glucose and LE improved diagnostic accuracy and increased the positive predictive value from 34.6% to 94.4%, with no significant impact on test sensitivity and negative predictive value [ 5 ]. Apart from the fact that Omar et al, analyzed test performance in native joints, no detailed information on participant characteristics was available to explain the variance in synovial glucose and LE apart from septic reasons.…”

“…According to the data previously published by Parvizi et al, the LE values “-” and “+” were considered as negativity cut-off [ 11 ]. With respect to glucose concentration, no change of color at the test pad represented a diminished amount of glucose in the synovial fluid [ 5 ].…”

“…Apart from septic complications, nonseptic inflammatory joint diseases are thought to be associated with increased leukocyte concentration and, therefore, lead to false-positive test results when synovial fluid is examined for LE alone. Omar et al, reported that analysis of synovial glucose levels using the reagent strip test or a glucometer provides an additional diagnostic tool to distinguish between different inflammatory states of native joints [ 5 , 6 ]. A normal synovial sample contains approximately 3.3–5.3 mmol/L glucose, which corresponds to the glucose level in human plasma [ 7 ].…”

Identifying bacterial infections in synovial structures—When will the Cavalry arrive?

“…The authors describe techniques that provide supportive evidence for a diagnosis of sepsis such as cytological examination of fluid, total protein concentrations, synovial fluid serum amyloid A concentrations and glucose concentration. In humans, a recent study demonstrated encouraging patient side results using test strips for semi-quantitative analysis of leucocyte esterase and glucose concentrations in joint fluid from suspected septic arthritis patients presenting for emergency care (Kolbeck et al 2021). This interesting application requires only a small drop of fluid.…”

“…In humans, a recent study demonstrated encouraging patient side results using test strips for semi‐quantitative analysis of leucocyte esterase and glucose concentrations in joint fluid from suspected septic arthritis patients presenting for emergency care (Kolbeck et al . 2021). This interesting application requires only a small drop of fluid.…”