Meningitis (Bacterial, Acute)

Clinical assessment

High index of suspicion based on acute onset of fever, headache, neck stiffness, and altered mental status. Presence of rash increases suspicion for meningococcal disease.

Differential diagnosis

• Viral meningitis/encephalitis.
• Subarachnoid haemorrhage.
• Brain abscess.
• Cerebral malaria.
• Tuberculous meningitis (subacute onset).
• Cryptococcal meningitis (subacute, esp. HIV+).
• Drug reactions / Toxic encephalopathy.

Investigations

• Lumbar Puncture (LP) and Cerebrospinal Fluid (CSF) Analysis: CRITICAL diagnostic test. Perform promptly unless contraindicated (signs of markedly raised ICP, severe coagulopathy).
• - CSF Appearance: Usually cloudy/turbid.
• - CSF Opening Pressure: Usually elevated.
• - CSF Cell Count & Differential: High WBC count (>100-1000s), predominantly Neutrophils.
• - CSF Glucose: Low (<40% of serum glucose).
• - CSF Protein: Elevated (>45-100 mg/dL).
• - CSF Gram Stain: May identify bacteria (e.g., Gram+ cocci - Pneumococcus; Gram- diplococci - Meningococcus; Gram- coccobacilli - Haemophilus).
• - CSF Culture & Sensitivity: Definitive identification and antibiotic susceptibility.
• - Consider CSF Antigen tests (e.g., Latex agglutination) if available.
• Blood Cultures: Obtain BEFORE starting antibiotics.
• Blood Glucose: Obtain concurrently with LP for CSF:Serum glucose ratio.
• Full Blood Count (FBC): Leucocytosis common.
• Consider CT Head before LP ONLY if focal neurological signs, papilloedema, GCS<10, new seizure, or immunocompromised (to rule out mass effect).

Diagnostic criteria

Clinical syndrome + CSF findings consistent with bacterial meningitis (high neutrophils, low glucose, high protein) +/- Positive Gram stain/Culture/Antigen test.

Non-pharmacological management

• Urgent Hospital Admission.
• Isolation: Droplet precautions for suspected/confirmed meningococcal meningitis for first 24h of effective antibiotic therapy.
• Supportive Care:
• - IV fluids (maintain hydration, avoid overhydration).
• - Control fever (paracetamol).
• - Manage seizures (diazepam/lorazepam).
• - Nutritional support (NGT if needed).
• - Monitor vital signs, neurological status, fluid balance, urine output.
• - Intensive care support if needed (airway management, shock management).

Pharmacological treatment

• Immediate Empirical IV Antibiotics: Start ASAP after LP (or immediately if LP delayed/contraindicated). DO NOT delay antibiotics waiting for imaging/LP results if high suspicion.
• - Recommended Empirical Regimen (UCG): Ceftriaxone 2g IV Q12H (Adult); 100mg/kg/day divided Q12H (Child). (LOC: HC4/H)
• - Alternative if Ceftriaxone unavailable/not improving: Chloramphenicol 1g IV Q6H (Adult); 25mg/kg/dose Q6H (Child).
• - Add Vancomycin if high prevalence of penicillin-resistant Pneumococcus suspected (specialist advice).
• - Add Ampicillin if Listeria suspected (neonates, elderly >50, immunocompromised).
• Targeted Antibiotic Therapy (Once organism identified): Adjust based on culture/sensitivity results and local guidelines.
• - Streptococcus pneumoniae: Benzylpenicillin 3-4 MU IV Q4H (Child: 100k IU/kg/dose) OR Ceftriaxone 2g IV Q12H (Child: 100mg/kg/day). Duration 10-14 days.
• - Neisseria meningitidis: Benzylpenicillin 5-6 MU IV Q6H (Child: 100k-150k IU/kg/dose) OR Ceftriaxone 2g IV Q12H (Child: 100mg/kg/day). Duration 7-14 days.
• - Haemophilus influenzae: Ceftriaxone 2g IV Q12H (Child: 100mg/kg/day). Alternative if susceptible: Ampicillin or Chloramphenicol. Duration 10 days.
• - Listeria monocytogenes: Benzylpenicillin or Ampicillin (higher doses) + Gentamicin. Duration >= 3 weeks.
• Adjunctive Dexamethasone: Consider giving IV dexamethasone (0.15 mg/kg Q6H for 2-4 days) just before or with the first dose of antibiotics ONLY in suspected bacterial meningitis in adults and children >6 weeks (especially Hib or Pneumococcal). Benefits controversial, may reduce hearing loss/neurological sequelae. Do not start later.
• Chemoprophylaxis for Close Contacts (Meningococcal Meningitis ONLY):
• - Ciprofloxacin 500mg PO single dose (Adult/Child >12y); 10mg/kg single dose (Child <12y).
• - Alternative: Ceftriaxone 250mg IM single dose (Adult); 125mg IM single dose (Child <12y). Or Rifampicin PO for 2 days.

Monitoring

Monitor clinical response (fever, headache, consciousness). Monitor neurological status. Repeat LP usually not needed unless poor response. Monitor for complications.