2026 年 5 巻 2 号 p. 58-66
Background: Bacterial meningitis (BM) is a life-threatening condition requiring early diagnosis and treatment to prevent severe complications; however, traditional diagnostic methods, such as cerebrospinal fluid (CSF) analysis, Gram staining, and bacterial cultures, can be slow/nonspecific. Therefore, novel biomarkers are needed. IL-6 levels increase during inflammatory responses, whereas procalcitonin (PCT) levels specifically increase during bacterial infections. Herein, we investigated the utility of CSF IL-6 and PCT levels to differentiate BM from other central nervous system (CNS) diseases.
Methods: CSF samples were collected from 70 patients (mean age, 37.5 years; SD, 17.8 years; male/female, 36/34) treated at Kawaguchi Municipal Medical Center between September 2022 and 2023. Blood samples were additionally collected from 53 patients. BM was diagnosed based on clinical symptoms, culture results, and antibiotic responses. CSF IL-6 and PCT concentrations were measured using electrochemiluminescence immunoassays.
Results: CSF IL-6 and PCT levels were significantly higher in patients with BM than those with non-bacterial CNS diseases. Receiver operating characteristic analysis revealed that CSF PCT had a higher diagnostic accuracy (area under the curve = 0.887) than CSF IL-6 and cell counts. Concurrent measurement of CSF IL-6 and PCT levels improved the specificity of BM diagnosis from 0.71 to 0.95.
Conclusions: Combining CSF IL-6 and PCT measurements provides better diagnostic accuracy for BM than either marker alone. CSF IL-6 primarily reflects intrathecal production, and although a weak correlation with serum IL-6 was observed, it remains unclear whether serum IL-6 contributes to CSF levels. PCT remains highly specific to bacterial infections.Further large-scale studies are required to validate these findings and confirm the utility of these biomarkers in clinical settings.
