Model Answer
0 min readIntroduction
Meningitis, an inflammation of the meninges, presents with a classic triad of headache, fever, and nuchal rigidity. Altered sensorium indicates a severe infection potentially leading to encephalopathy. Rapid diagnosis and treatment are crucial to prevent significant morbidity and mortality. This clinical presentation strongly suggests acute meningitis, requiring immediate investigation and intervention. The etiology can be bacterial, viral, fungal, or parasitic, each demanding a specific therapeutic approach.
(i) Diagnosis and Common Organisms
The most likely diagnosis is acute meningitis, given the patient’s presentation of headache, fever, vomiting, altered sensorium, and neck rigidity. The rapid onset (five days) further supports this diagnosis.
Common Organisms Causing Meningitis:
- Bacterial Meningitis:
- Neisseria meningitidis (Meningococcus): A leading cause, particularly in outbreaks.
- Streptococcus pneumoniae (Pneumococcus): Common in adults and children, often following respiratory infections.
- Haemophilus influenzae type b (Hib): Less common due to widespread vaccination, but still a concern in unvaccinated individuals.
- Listeria monocytogenes: Primarily affects newborns, elderly, and immunocompromised individuals.
- Streptococcus agalactiae (Group B Streptococcus): Common cause of meningitis in neonates.
- Viral Meningitis:
- Enteroviruses (e.g., Coxsackievirus, Echovirus): Most common cause of viral meningitis, typically milder than bacterial.
- Herpes Simplex Virus (HSV): Can cause severe encephalitis and meningitis.
- Varicella-Zoster Virus (VZV): Can cause meningitis as a complication of chickenpox or shingles.
- Fungal Meningitis:
- Cryptococcus neoformans: Common in immunocompromised patients, particularly those with HIV/AIDS.
- Coccidioides immitis: Found in the southwestern United States.
- Parasitic Meningitis:
- Angiostrongylus cantonensis: (Rat Lungworm) – associated with consumption of raw or undercooked snails or slugs.
(ii) Expected CSF Examination Findings
Cerebrospinal fluid (CSF) analysis is crucial for confirming the diagnosis and identifying the causative organism. The expected findings are:
| Parameter | Bacterial Meningitis | Viral Meningitis | Fungal Meningitis |
|---|---|---|---|
| Appearance | Turbid/Purulent | Clear | Clear or slightly turbid |
| Opening Pressure | Increased | Normal or slightly increased | Increased |
| White Blood Cell Count (WBC) | >1000 cells/µL (primarily neutrophils) | 50-500 cells/µL (primarily lymphocytes) | 50-500 cells/µL (lymphocytes) |
| Protein | Increased (>45 mg/dL) | Normal or slightly increased | Increased (>45 mg/dL) |
| Glucose | Decreased (<40 mg/dL) | Normal | Decreased |
| Gram Stain | Positive in many cases | Negative | Negative |
| Culture | Positive in many cases | Negative | Positive (requires prolonged incubation) |
Additional tests like PCR for viral pathogens and India ink staining for Cryptococcus may be performed.
(iii) Drugs Used to Manage the Case
Empiric antibiotic therapy should be initiated immediately after obtaining CSF samples, pending culture results. The choice of antibiotics depends on the patient’s age, immune status, and local antibiotic resistance patterns.
- Bacterial Meningitis:
- Adults: Ceftriaxone + Vancomycin (covers most common pathogens). Consider adding ampicillin if Listeria is suspected.
- Neonates: Ampicillin + Gentamicin.
- Children: Ceftriaxone or Cefotaxime + Vancomycin.
- Viral Meningitis: Supportive care is usually sufficient. Acyclovir is indicated for HSV meningitis.
- Fungal Meningitis: Amphotericin B followed by oral fluconazole for Cryptococcus.
- Adjunctive Therapy: Dexamethasone may be considered in cases of pneumococcal meningitis to reduce inflammation.
Supportive care includes managing fever, maintaining hydration, and controlling seizures.
Conclusion
Acute meningitis is a life-threatening condition requiring prompt diagnosis and treatment. A thorough clinical evaluation, coupled with CSF analysis, is essential for identifying the causative organism and initiating appropriate therapy. Empiric antibiotic treatment should be started immediately, and adjusted based on culture and sensitivity results. Early intervention significantly improves patient outcomes and reduces the risk of long-term neurological sequelae.
Answer Length
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