Early diagnosis of septic arthritis in immunocompromised patients

Determining the accuracy of the leukocyte esterase reagent strip test in the rapid diagnosis of adult septic arthritis

BACKGROUNDS

Septic arthritis is a dangerous disease that occurs when microorganisms enter synovial fluid. It needs fast and accurate management; otherwise, it can harm the patient's life. Currently, the tests measure WBC and PMN in SF, so we hypothesized to use a proxy that is easier and faster to measure. Leukocyte esterase is an enzyme secreted by neutrophils that can be found in the synovial fluid of SA patients. In this study, we tried to investigate the sensitivity and specificity of leukocyte esterase in diagnosing septic arthritis.

METHODS

We obtained synovial fluid samples from forty-six patients suspected of having septic arthritis and fifty-eight healthy individuals and measured the WBCs, ESR, CRP, PMN, glucose, and protein of SF in 2021. We also used the leukocyte esterase dipstick test to investigate the level of LE in synovial fluid for one minute.

RESULTS

Based on clinical and paraclinical criteria, sixteen out of the forty-six patients were diagnosed with SA. When (++) was considered positive, the sensitivity and specificity of the LE dipstick test for the diagnosis of SA were 93.7% (95% CI: 81.8-100%) and 60% (95% CI: 42.4-77.5%, P = 0.000), respectively. When both (+) and (++) were considered positive, they were 100% and 43.3% (95% CI: 25.6-61.0% P = 0.000), respectively. All the patients in the control group had negative cultures and LE test readings (specificity = 100%).

CONCLUSION

The LE dipstick test can be a valuable diagnostic tool in the initial diagnosis of SA since it is affordable, fast, and reliable.

Effects of immunocompromised status on diagnostic criteria in septic arthritis

Introduction

Septic arthritis is an orthopaedic emergency, with permanent cartilage damage possible within hours of the onset of symptoms. Diagnostic criteria for septic arthritis in immunocompetent patients are well established, however, there is a paucity of literature evaluating diagnostic criteria in immunocompromised patients. The purpose of this retrospective case-control study was to evaluate the laboratory and clinical information of immunocompromised patients with septic arthritis and compare them to immunocompetent patients with septic arthritis to enable physicians to diagnose septic arthritis more accurately in this population.

Methods

All patients at our institution, a level I trauma center, with a clinical diagnosis of septic arthritis between January 1, 2006 and November 1, 2021 were identified and reviewed retrospectively. Patients 18 years old or older were screened for immunocompromised status and those meeting criteria were included for review. The control cohort was matched by the joint affected and age. Data were analyzed using the Shapiro-Wilk test, Turkey's test, Mann-Whitney U test, independent sample t-test, and chi-square analysis. A p-value of <0.05 was considered significant.

Results

A total of 36 patients with positive joint aspirate cultures were compared (18 immunocompetent and 18 immunocompromised). The immunocompromised group had a significantly longer length of hospital stay than the immunocompetent group (p = 0.044). There was no significant difference in erythrocyte sedimentation rate (ESR) (p = 0.852), peripheral white blood cell count (pWBC) (p = 0.696), joint aspirate white blood cell count (aWBC) (p = 0.901), polymorphonuclear cell percentage (PMN%) (p = 0.325), or total operations performed per patient (p = 0.365).

Conclusion

At our institution, immunocompromised patients with septic arthritis did not have significantly different diagnostic laboratory values when compared to immunocompetent patients. This suggests that immunocompromised patients with suspicion of septic arthritis can be assessed with similar diagnostic criteria as immunocompetent individuals; however, a larger cohort study is needed to assess the difference more precisely in laboratory values.

Assessment for Septic Arthritis in Immunocompetent and Immunocompromised Patients: A Single-Institution Study

INTRODUCTION

Prompt diagnosis of septic arthritis is imperative to prevent irreversible joint damage. Immunocompromised patients are at an increased risk of septic arthritis as well as secondary systemic infection. Our aims were to identify features predictive of septic arthritis and to determine whether these features differed between immunocompetent and immunocompromised patients.

METHODS

A single institution retrospective cohort study was performed of 173 immunocompetent and 70 immunocompromised patients who underwent aspiration or arthrotomy for suspected septic arthritis from 2010 to 2018. Demographic data, symptoms, laboratory values, and imaging findings were recorded. Multiple variable logistic regression models were used to assess for predictive factors for septic arthritis in both cohorts. Results were reported as odds ratios, 95% confidence intervals, and P values.

RESULTS

In the regression analysis, independent predictive factors for septic arthritis in immunocompetent patients were younger age (P = 0.004), presence of radiographic abnormalities (P = 0.006), and C-reactive protein (CRP) (P < 0.001). For immunocompromised patients, only CRP was an independent continuous predictive factor (P = 0.008) for septic arthritis. A risk stratification tool for predicting septic arthritis in immunocompetent patients using age <55 years, CRP >100 mg/dL, and presence of radiographic abnormalities was developed. A similar tool was created using CRP >180 mg/dL and radiographic abnormalities in immunocompromised patients.

DISCUSSION

Differences in predictive factors for septic arthritis between immunocompromised and immunocompetent patients suggest dissimilar clinical presentations. The developed risk stratification tools allow one to predict the likelihood of septic arthritis in both groups. This may permit more accurate selection of patients for surgical intervention in the setting of insufficient data from synovial aspiration.

What are the best diagnostic tests for diagnosing bacterial arthritis of a native joint? : a systematic review of 27 studies

AIMS

This study aimed to answer two questions: what are the best diagnostic methods for diagnosing bacterial arthritis of a native joint?; and what are the most commonly used definitions for bacterial arthritis of a native joint?

METHODS

We performed a search of PubMed, Embase, and Cochrane libraries for relevant studies published between January 1980 and April 2020. Of 3,209 identified studies, we included 27 after full screening. Sensitivity, specificity, area under the curve, and Youden index of diagnostic tests were extracted from included studies. We grouped test characteristics per diagnostic modality. We extracted the definitions used to establish a definitive diagnosis of bacterial arthritis of a native joint per study.

RESULTS

Overall, 28 unique diagnostic tests for diagnosing bacterial arthritis of a native joint were identified. The following five tests were deemed most useful: serum ESR (sensitivity: 34% to 100%, specificity: 23% to 93%), serum CRP (sensitivity: 58% to 100%, specificity: 0% to 96%), serum procalcitonin (sensitivity: 0% to 100%, specificity: 68% to 100%), the proportion of synovial polymorphonuclear cells (sensitivity: 42% to 100%, specificity: 54% to 94%), and the gram stain of synovial fluid (sensitivity: 27% to 81%, specificity: 99% to 100%).

CONCLUSION

Diagnostic methods with relatively high sensitivities, such as serum CRP, ESR, and synovial polymorphonuclear cells, are useful for screening. Diagnostic methods with a relatively high specificity, such as serum procalcitonin and synovial fluid gram stain, are useful for establishing a diagnosis of bacterial arthritis. This review helps to interpret the value of various diagnostic tests for diagnosing bacterial arthritis of a native joint in clinical practice. Cite this article: Bone Joint J 2021;103-B(12):1745-1753.

Optimal Synovial Fluid Leukocyte Count Cutoff for Diagnosing Native Joint Septic Arthritis After Antibiotics: A Receiver Operating Characteristic Analysis of Accuracy

INTRODUCTION

Urgent treatment of septic arthritis is key in preventing devastating morbidity or mortality. Accurate diagnosis is critical, and the standard diagnostic cutoff of 50,000 synovial leukocytes may be altered by previous administration of antibiotics. Our objective was to identify and compare a cutoff synovial leukocyte count with a high sensitivity and specificity for diagnosis of septic arthritis in patients who received antibiotics and those who had not. A receiver operating characteristic (ROC) curve was used to provide a discriminate cutoff value for diagnosing septic arthritis.

METHODS

A retrospective chart review of 383 patients was done over a 13-year period including those who had arthrocentesis of any joint. Two groups were created, those who had not been given antibiotics within 2 weeks (control) and those who received intravenous or oral antibiotics within 2 weeks before arthrocentesis. Relevant data included synovial leukocyte count and differential cell count. Additional metrics included temperature, erythrocyte sedimentation rate, and C-reactive protein. A ROC curve determined the optimal synovial white blood cell cutoff for diagnosing septic arthritis in native joints for each group.

RESULTS

The ROC curve determined that patients who received antibiotics had an optimal cutoff of >16,000 cells (sensitivity = 82%, specificity = 76%), and a neutrophil percentage cutoff of >90% (sensitivity = 73%, specificity = 74%). The control group had an optimal synovial leukocyte cutoff of >33,000 cells (sensitivity = 96%, specificity = 95%). The optimal neutrophil percentage cutoff in the control group was >83% neutrophils (sensitivity = 89%, specificity = 79%).

CONCLUSION

When a patient is given antibiotics before arthrocentesis, a diagnostic value of >16,000 synovial leukocytes should be used to guide treatment of septic arthritis. A diagnostic value of >33,000 synovial leukocytes yields the highest accuracy for diagnosis of septic arthritis in patients who have not been given antibiotics before arthrocentesis.

LEVEL OF EVIDENCE

III.

Gram stain microscopy in septic arthritis

Septic arthritis is a serious condition that can lead to rapid destruction of joint if it is not rapidly diagnosed and treated appropriately. The reported annual incidence is 10 in 100 000 although this increases to 70 in 100 000 in those with risk factors for developing septic arthritis mainly rheumatoid arthritis and immune-compromised patients. The aim of this study is to examine the sensitivity and specificity, and thus the clinical usefulness, of gram stain results. This was a single centre, retrospective case series. All joint aspirates over a three year period from May 2015 to April 2018 were reviewed. The gram stain and final culture results noted. 830 samples were included from both native and replaced joints. Native joints accounted for a total of 701 cases (84%) of the aspirates, whilst those obtained from prosthetic joints 129 (16%). In 74 (9%) cases there was a discrepancy between the gram stain and culture results. The sensitivity of the gram stain in this case series is 22% and the specificity of the test is 99.6%. The clinician should have a low threshold for overlooking a negative gram stain result and place greater emphases on the clinical findings in conjunction with biochemical markers.

Diffuse Recalcitrant Osteomyelitis and Joint Septicemia Because of Bowel Perforation Secondary to Gunshot Injury: A Case Report

CASE

A previously healthy 22-year-old man was brought into the emergency department after sustaining a low-velocity, civilian gunshot wound to the abdomen that perforated the bowel. Over the next 300 days, he would be admitted and discharged multiple times, requiring a total of 48 debridements, 23 different antimicrobials in 81 unique combinations, and had 18 different microbes cultured from various sites in bone, joint, and blood. Multiorganism bacteremia and fungemia culminated in above-knee amputation because of progression of infection, all in a nonimmunocompromised host.

CONCLUSION

Despite following clinical guidelines, patients can still fail evidence-based treatment algorithms. A humbling reminder is that medicine is never one-size-fits-all.

Septic Arthritis: An Evidence-Based Review of Diagnosis and Image-Guided Aspiration

OBJECTIVE. The purpose of this evidence-based review is to equip radiologists to discuss and interpret findings obtained with various imaging modalities, guide patient selection for percutaneous aspiration, and safely perform arthrocentesis to assess for infection in both native and prosthetic joints. CONCLUSION. Septic arthritis is an emergency that can lead to rapidly progressive, irreversible joint damage. Despite the urgency associated with this diagnosis, there remains a lack of consensus regarding many aspects of the management of native and periprosthetic joint infections.