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Meningitis

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Quick Overview

Meningitis is inflammation of the meninges requiring emergency recognition and treatment. NICE NG240 emphasizes immediate antibiotic administration before transfer/investigations if suspected. Bacterial meningitis (mortality 10-15%) demands urgent intervention; viral is self-limiting. Key skills: recognizing clinical features, interpreting CSF parameters, administering pre-hospital antibiotics, and providing chemoprophylaxis to contacts.

Core Facts & Concepts

Clinical Features (Classical Triad in 44% only)

  • Headache (severe, sudden-onset)
  • Fever (>38°C)
  • Neck stiffness (meningism)
  • Additional: photophobia, altered consciousness (GCS <14), seizures, non-blanching rash

Emergency Antibiotic Timing (NICE NG240)

  • Pre-hospital: IM/IV benzylpenicillin 1.2g (adult) if suspected bacterial meningitis
  • Hospital <1 hour: IV ceftriaxone 2g (adult) before LP if no contraindication
  • Do NOT delay antibiotics for LP/imaging if bacterial meningitis suspected

LP Contraindications

  • GCS ≤12 or deteriorating consciousness
  • Focal neurological signs
  • Papilloedema
  • Signs of raised ICP (bradycardia, hypertension, irregular respirations)
  • Coagulopathy (platelets <100, INR >1.4)
  • Infection at LP site

![CSF microscopy showing numerous polymorphonuclear neutrophils in bacterial meningitis](Image: bacterial meningitis CSF microscopy)

CSF Interpretation Thresholds

ParameterBacterialViralNormal
AppearanceTurbid/cloudyClearClear
WCC (cells/mm³)>1000 (PMN)10-1000 (lymph)<5
Protein (g/L)>1.00.4-1.0<0.45
Glucose (CSF:blood)<0.4>0.6>0.6
Opening pressure↑↑ (>25 cmH₂O)Normal/↑10-20 cmH₂O

Problem-Solving Approach

Emergency Management Sequence

  1. Recognize meningitis signs (headache + fever ± meningism)
  2. Assess severity: GCS, signs of raised ICP, septic shock
  3. Blood cultures + blood glucose (for CSF:blood ratio)
  4. Antibiotics within 1 hour: IV ceftriaxone 2g BD (+ ampicillin if >55 years/immunocompromised for Listeria)
  5. CT head before LP if: GCS ≤12, focal signs, papilloedema, seizures, immunocompromised
  6. LP if safe: opening pressure, cell count/differential, protein, glucose, Gram stain, culture, PCR (meningococcal/pneumococcal)
  7. Dexamethasone: 10mg IV QDS for 4 days if bacterial suspected (before/with first antibiotic dose)

Figure 1: Non-blanching purpuric rash on skin indicating meningococcal septicaemia

🚩 Red Flags

  • Non-blanching rash = meningococcal septicaemia (antibiotics IMMEDIATELY)
  • Rapid deterioration in GCS
  • Signs of raised ICP (Cushing's triad)

Analysis Framework

Bacterial vs Viral Differentiation

FeatureBacterialViral
OnsetHours (rapid)Days (gradual)
SeverityCritically unwellMild-moderate
RashPurpuric (meningococcal)Absent
CSF WCC>1000 PMN10-1000 lymphocytes
CSF protein>1.0 g/L0.4-1.0 g/L
CSF glucose<40% blood>60% blood
Gram stainPositive (60-90%)Negative

Chemoprophylaxis for Contacts (NICE NG240)

  • Who: Household/kissing contacts within 7 days of illness onset
  • When: Within 24 hours of index case diagnosis
  • Regimen:
    • Ciprofloxacin 500mg single dose (adult) OR
    • Rifampicin 600mg BD for 2 days (adult)
  • Applies to: Meningococcal and Hib meningitis only

Visual Aid

Common Causative Organisms by Age

Age GroupMost Common Organisms
Neonates (<3 months)Group B Strep, E. coli, Listeria
Children/AdultsN. meningitidis, S. pneumoniae
>55 yearsS. pneumoniae, Listeria, Gram-negatives
ImmunocompromisedListeria, TB, Cryptococcus

Key Points Summary

Antibiotics <1 hour: IV ceftriaxone 2g before LP if bacterial meningitis suspected (NICE NG240)

CSF thresholds: Bacterial = WCC >1000 PMN, protein >1.0, glucose <40% blood; Viral = lymphocytic, protein 0.4-1.0, glucose >60%

LP contraindications: GCS ≤12, focal signs, papilloedema, raised ICP signs, coagulopathy

Dexamethasone 10mg IV QDS for 4 days if bacterial meningitis (give before/with antibiotics)

Chemoprophylaxis: Ciprofloxacin 500mg single dose for household/kissing contacts within 24 hours (meningococcal/Hib only)

Non-blanching rash = meningococcal septicaemia requiring immediate antibiotics (don't wait for LP)

Add ampicillin to ceftriaxone if >55 years/immunocompromised for Listeria coverage

⚠️ Warning: Never delay antibiotics for imaging or LP in suspected bacterial meningitis - mortality increases significantly with treatment delay

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Meningitis – UKMLA Infectious Diseases Notes | Oncourse