Meningitis

Meningitis can be caused by various pathogens, including bacteria, viruses, fungi, and parasites. Bacterial meningitis is generally more severe and can lead to critical complications if not promptly treated. The most common bacteria involved are Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b. Viral meningitis, although less severe, is more common and is usually caused by enteroviruses. Other forms include fungal meningitis, commonly associated with Cryptococcus neoformans, and parasitic meningitis, which is relatively rare.

The pathophysiology involves the crossing of the blood-brain barrier by the infectious agents, leading to the activation of immune responses. This results in the release of pro-inflammatory cytokines, causing edema and increased intracranial pressure.

The gold standard for meningitis diagnosis is a lumbar puncture, which allows for the analysis of cerebrospinal fluid (CSF). The CSF is examined for parameters like cell count, glucose levels, and protein concentration. Microbial culture and polymerase chain reaction (PCR) tests can identify the causative agent. Additionally, imaging studies like MRI or CT scans may be employed to rule out other causes of symptoms.