Etiology, Pathogenesis, Clinical Presentation, and Laboratory Diagnosis of Meningitis

Introduction

Meningitis is a serious medical condition characterized by inflammation of the meninges, the protective membranes surrounding the brain and spinal cord. It can be caused by various infectious agents, including bacteria, viruses, fungi, and parasites.

Etiology

Meningitis has multiple etiological causes. The most common bacterial pathogens include Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. Viral meningitis is primarily caused by enteroviruses, herpes simplex virus, and mumps virus.

Pathogenesis

Pathogens enter the central nervous system through hematogenous spread, direct extension from nearby infections, or penetrating trauma. The immune response leads to inflammation, increased intracranial pressure, and neurological complications.

Clinical Presentation

Common symptoms of meningitis include:

• Severe headache
• Neck stiffness
• Fever
• Nausea and vomiting
• Photophobia
• Altered mental status

Laboratory Diagnosis

Diagnosis of meningitis involves several laboratory tests:

• Cerebrospinal Fluid (CSF) Analysis: Elevated white blood cells, increased protein, and decreased glucose suggest bacterial meningitis.
• Gram Stain and Culture: Identifies bacterial pathogens.
• Polymerase Chain Reaction (PCR): Useful for viral meningitis diagnosis.
• Blood Cultures: Identifies systemic infections.

Differential Diagnosis

Conditions that may mimic meningitis include:

• Subarachnoid hemorrhage
• Brain abscess
• Encephalitis
• Drug-induced meningitis

Conclusion

Prompt recognition and treatment of meningitis are crucial for reducing morbidity and mortality. Empirical antibiotic therapy should be initiated while awaiting confirmatory test results.