Meningitis: Etiology, Types, Pathogenesis, Differentiating Factors, and CSF Findings

Introduction

Meningitis is the inflammation of the meninges, primarily caused by infections. It can lead to severe complications if untreated. Understanding its etiology, types, and pathogenesis is crucial for early diagnosis and appropriate management.

Etiology of Meningitis

Meningitis can be caused by various pathogens, including:

• Bacterial: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae
• Viral: Enteroviruses, Herpes simplex virus
• Fungal: Cryptococcus neoformans
• Parasitic: Angiostrongylus cantonensis

Types of Meningitis

Meningitis can be classified into different types based on its causative agent:

• Acute Bacterial Meningitis
• Viral (Aseptic) Meningitis
• Chronic Meningitis
• Fungal Meningitis

Pathogenesis: Mechanisms of Infection and Inflammatory Response

Pathogens enter the central nervous system (CNS) through hematogenous spread or direct invasion, leading to inflammation. Key mechanisms include:

1. Blood-brain barrier disruption
2. Release of pro-inflammatory cytokines (IL-1, TNF-α)
3. Leukocyte infiltration leading to increased intracranial pressure

Differentiating Factors

Distinct clinical and laboratory features help in differentiating types of meningitis:

Feature	Bacterial Meningitis	Viral Meningitis
Onset	Sudden, severe	Gradual, mild
CSF Findings	High WBC, Low glucose, High protein	Moderate WBC, Normal glucose, Mild protein elevation

Conclusion

Early detection and appropriate treatment of meningitis can prevent serious complications. Awareness of its etiology, pathogenesis, and CSF findings plays a vital role in medical management.