They test for meningitis primarily through a combination of physical examinations, blood tests, and cerebrospinal fluid (CSF) analysis. The most definitive test is a lumbar puncture (spinal tap) to collect CSF, which is then analyzed for signs of infection, such as elevated white blood cells, proteins, and presence of bacteria, viruses, or fungi. Blood cultures and other blood tests (like procalcitonin levels) help determine the type of infection causing meningitis. Imaging tests such as CT scans may be done before a lumbar puncture if there is concern about elevated pressure in the brain.
Key Meningitis Tests
- Physical Exam: Tests like the Brudzinski and Kernig signs detect meninges inflammation through neck and leg movements.
- Blood Tests and Cultures: Look for infection markers including white blood cells, procalcitonin, and bacterial cultures for specific pathogens.
- Lumbar Puncture (Spinal Tap): Collects CSF to directly examine for infection; CSF analysis is the gold standard for diagnosing meningitis and identifying the causative agent.
- Imaging Tests: CT or MRI scans may be used to check for brain swelling or to ensure the safety of performing a lumbar puncture.
Advanced testing includes nucleic acid amplification tests (NAAT) like PCR on CSF to rapidly identify bacterial, viral, or fungal DNA. In summary, meningitis diagnosis depends largely on CSF examination from a lumbar puncture, supported by blood tests and physical examination findings to confirm and guide treatment.
