Dilemma in Diagnosis of Pyogenic Meningitis in Cerebrospinal Fluid Contaminated with Blood: Does Leucocyte Esterase Test Help?

Point of care testing for the diagnosis of periprosthetic joint infections: a review

BACKGROUND

Periprosthetic joint infection (PJI) remains a major complication following total joint arthroplasties (TJA), significantly affecting patient outcomes and healthcare costs. Despite advances in diagnostic techniques, challenges persist in accurately diagnosing PJI, underscoring the need for effective point-of-care testing (POCT).

METHODS

This review examines the current literature and latest developments in POCT for diagnosing PJI, focusing on biomarkers such as alpha-defensin, leukocyte esterase, calprotectin, and C-reactive protein (CRP). Criteria from various societies like the Musculoskeletal Infection Society, Infectious Diseases Society of America, and the International Consensus Meeting were compared to evaluate the effectiveness of these biomarkers in a point-of-care setting.

RESULTS

POCT provides rapid results essential for the timely management of PJI, with alpha-defensin and leukocyte esterase showing high specificity and sensitivity. Recent advancements have introduced novel biomarkers like calprotectin, which demonstrate high diagnostic accuracy. However, challenges such as the variability in test performance and the need for validation under different clinical scenarios remain.

DISCUSSION

While POCT for PJI shows promising results, their integration into clinical practice requires standardized protocols and further validation. The evolution of these diagnostic tools offers a potential shift toward more personalized and immediate care, potentially improving outcomes for patients undergoing TJA.

Role of neonatal cerebrospinal fluid cytology in correlation to C-reactive protein, blood culture, risk factors and clinical outcomes in neonatal intensive care

Introduction

The number of neonatal cerebrospinal fluid (CSF) samples sent from the neonatal intensive care unit (NICU) for cytologic examination is rising, warranting accurate analysis and interpretation of the same. This study was taken up to assess the usefulness of CSF cell count and cytology in NICU settings, as it can be used even in a resource-limited setting.

Aim and Objective

1) To study the prevalence of cell count and cytologic changes in CSF from NICU and assess their usefulness in correlation to C-reactive protein, CSF neutrophil percentage, blood, CSF culture, and other biochemical parameters. 2) To correlate cell counts and cytology with age, period of gestation, presence, and absence of sepsis, seizures, intracranial hemorrhage, and their clinical follow-up.

Materials and Methods

A retrospective study was done on neonatal CSF samples submitted for cytology over one year (January-December 2016) in the Department of Pathology. CSF cell counts were retrieved, and cytosmears were reviewed for cellularity, cell type, proportion, and background and correlated with the biochemical, microbiological, and clinicoradiological findings.

Results

A total of 213 samples were included with 140 males and 73 females with an age range of 0-28 (mean: 7.3) days. The mean CSF cell count was 5.48/cu.mm (0-90 cells/cu.mm). The most frequent cytologic finding was occasional lymphocytes or acellular CSF (63.9%). The CSF leucocyte count and protein levels showed a significant correlation with s C-reactive protein. The CSF cytology showed a significant correlation between the age of the neonate and blood neutrophil percentage (P = 0.0158). History of intracranial hemorrhage showed a significantly higher frequency of the presence of red blood cells (P = 0.0147).

Conclusion

Accurate cell counts, cytology of neonatal CSF, and biochemical and microbiological workup can help diagnose and manage neonates in intensive care.

Fecal Leukocyte Esterase, an Alternative Biomarker to Fecal Calprotectin in Inflammatory Bowel Disease: A Pilot Series

Background and Aims

Fecal calprotectin (FC) is a noninvasive biomarker used in inflammatory bowel disease (IBD) management and risk stratification of nonspecific gastrointestinal symptoms. Leukocyte esterase is an inexpensive and widely available point-of-care inflammatory marker present on urinalysis test strips. We aim to assess the diagnostic accuracy of fecal leukocyte esterase (FLE) relative to FC and endoscopy and demonstrate its use as an alternative biomarker for IBD.

Methods

In this prospective cohort study, 70 patients who had FC ordered as part of standard clinical care also received FLE testing. FLE levels were compared with various FC cutoff values and endoscopy and pathology findings as the gold standard.

Results

As the FC cutoff increased from 50 to 500 μg/g, FLE sensitivity increased from 67% to 95% while the specificity decreased from 86% to 76%. The area under the receiver operating characteristic (AUROC) curve increased from 0.79 to 0.90. An FLE of ≥1+ had the best test characteristics. Among patients who underwent endoscopic evaluation, FLE demonstrated an identical sensitivity (75%) and specificity (86%) to FC in predicting endoscopic inflammation. AUROC was 0.80 for FLE and 0.85 for FC with an optimal cutoff of ≥2+ and 301 μg/g, respectively. When used to distinguish between patients with active IBD and no/inactive IBD, FLE had a sensitivity of 84% and specificity of 90%, comparable with the 84% and 83%, respectively, of FC. AUROC was 0.88 for FLE and 0.91 for FC with an optimal cutoff of ≥2+ and 145 μg/g, respectively.

Conclusion

FLE demonstrates adequate correlation and comparable accuracy with FC in predicting endoscopic inflammation and distinguishing between patients with active vs inactive IBD.

Application of leukocyte esterase strip test in the screening of periprosthetic joint infections and prospects of high-precision strips

Periprosthetic joint infection (PJI) represents one of the most challenging complications after total joint arthroplasty (TJA). Despite the availability of a variety of diagnostic techniques, the diagnosis of PJI remains a challenge due to the lack of well-established diagnostic criteria. The leucocyte esterase (LE) strips test has been proved to be a valuable diagnostic tool for PJI, and its weight in PJI diagnostic criteria has gradually increased. Characterized by its convenience, speed and immediacy, leucocyte esterase strips test has a prospect of broad application in PJI diagnosis. Admittedly, the leucocyte esterase strips test has some limitations, such as imprecision and liability to interference. Thanks to the application of new technologies, such as machine reading, quantitative detection and artificial intelligence, the LE strips test is expected to overcome the limitations and improve its accuracy.

Effect of blood contamination of cerebrospinal fluid on amino acids, biogenic amines, pterins and vitamins

BACKGROUND

Cerebrospinal fluid (CSF) metabolomic investigations are a powerful tool for studying neurometabolic diseases. We aimed to assess the effect of CSF contamination with blood on the concentrations of selected biomarkers.

METHODS

CSF samples were spiked in duplicate with increasing volumes of whole blood under two conditions: (A) pooled CSF spiked with fresh whole blood and frozen to cause red blood cell (RBC) lysis; (B) pooled CSF spiked with fresh blood and centrifuged (the supernatant with no RBCs was frozen until the moment of analysis). CSF concentrations of amino acids, biogenic amines, pterins, and vitamins were analysed by HPLC coupled with tandem mass spectrometry, electrochemical and fluorescence detection.

RESULTS

Aspartate, glutamate, taurine, ornithine, glycine, citrulline, pyridoxal 5´-phosphate, 5-methyltetrahydrofolate, and thiamine showed higher values when RBCs were lysed when compared with those of CSF with no RBC, while arginine, 5-hydroxyindoleacetic and homovanillic acids showed lower values. When RBCs were removed from CSF, only some amino acids, thiamine and pyridoxal 5´-phosphate showed moderately higher values when compared with the non-spiked CSF sample.

CONCLUSIONS

CSF-targeted metabolomic analysis is feasible even when substantial RBC contamination of CSF has occurred since CSF centrifugation to remove RBC prior to freezing eliminated most of the interferences observed.