Bacterial Meningitis: An Overview of Immunologic and Biochemical Markers for Diagnosis.

Abstract

Background: Bacterial meningitis is a severe central nervous system (CNS) infection with high mortality and morbidity rates, especially in low-resource settings. Clinical symptoms often overlap with other illnesses, necessitating precise diagnostic methods.

Aim: This study reviews immunologic and biochemical markers for the early and accurate diagnosis of bacterial meningitis, with a focus on differentiating it from viral meningitis.

Methods: A comprehensive analysis of diagnostic assays, including cerebrospinal fluid (CSF) examination, Gram staining, and molecular methods like polymerase chain reaction (PCR) and next-generation sequencing (NGS), was conducted. Biomarkers such as protein, glucose, lactate, and bacterial antigens were also evaluated for their sensitivity and specificity in meningitis diagnosis.

Results: Bacterial meningitis is characterized by elevated CSF white blood cell counts, increased protein levels, decreased glucose ratios, and high lactate concentrations. Gram staining shows variable sensitivity (25%-97%), while bacterial culture remains the diagnostic gold standard despite limitations in low-resource settings and post-antibiotic administration. Molecular techniques, including PCR and NGS, significantly enhance sensitivity and specificity, with PCR showing near-perfect accuracy for targeted pathogens. Emerging biomarkers like CSF lactate demonstrated 93% sensitivity and 99% specificity at a cutoff of ≥35 mg/dL.

Conclusion: Early diagnosis of bacterial meningitis is critical for initiating effective treatment and reducing complications. Immunologic and biochemical markers, combined with advanced molecular diagnostics, show promise for overcoming limitations in traditional methods. Integrating these approaches can improve patient outcomes, particularly in resource-constrained settings.