Makindo Medical Notes

Related Subjects: | Pasteurella Multocida | Capnocytophaga canimorsus | Snake Bites | Dog Bites | Tetanus | Pasteurella multocida

⚠️ A non-blanching petechial rash is an ominous sign of meningococcaemia in an acutely unwell patient. Always perform the “glass test” 🥂.

📖 About

• Meningococcaemia → invasive infection with Neisseria meningitidis, causing meningitis and/or septicaemia.
• Patients with complement (C8/C9) deficiency are especially susceptible.

📊 Epidemiology

• 13+ serogroups; main ones: A, B, C, W-135, Y.
• In the UK 🇬🇧 → serogroups B & C predominate (MenB vaccine introduced in 2015, MenACWY for teenagers).
• Bimodal age peaks: infants <5 years 👶 and teenagers 15–19 years 🎓.

🏠 Source

• Carried in the nasopharynx of ~10% of asymptomatic individuals.

🔬 Characteristics

• Gram-negative, capsulated diplococcus (kidney-shaped).
• Cell wall LPS → overproduction causes DIC, petechiae, purpura.
• Ferments glucose + maltose.

🧬 Virulence Factors

• Polysaccharide capsule → blocks phagocytosis.
• Endotoxin (LPS blebbing) → cytokine storm, septic shock.
• Pili + IgA protease → adhesion and immune evasion.
• Very rapid doubling time → sudden clinical deterioration possible.

🩺 Clinical Manifestations

• Meningitis ± septicaemia (classic presentation).
• Septicaemia alone → fever, shock, rash.
• Complications:
  • Waterhouse-Friderichsen syndrome (adrenal haemorrhage 🧾).
  • DIC, multiorgan failure.
  • ARDS, purpura fulminans.

🔎 Investigations

• CSF Gram stain → Gram-negative diplococci inside PMNs.
• PCR for rapid confirmation (blood or CSF).
• Culture on chocolate agar or Thayer–Martin media (requires CO₂).
• Oxidase positive; ferments glucose + maltose.

💊 Antibiotic Sensitivities

• Penicillin
• Cefotaxime
• Ceftriaxone
• Rifampicin (for prophylaxis)
• Ciprofloxacin (alternative prophylaxis)

🩺 Management

• Pre-hospital: Suspected meningococcaemia with rash → give IM/IV benzylpenicillin immediately 🚑.
• Hospital therapy:
  • Ceftriaxone 2 g IV BD OR Cefotaxime 2 g IV q6h.
  • Penicillin (2.4 g IV q4h) if sensitive strain confirmed.
• Supportive: Aggressive fluids, vasopressors, ICU support for shock/DIC.
• Adrenal crisis: Give hydrocortisone if Waterhouse-Friderichsen suspected.
• Prophylaxis for contacts: Rifampicin, ciprofloxacin, or ceftriaxone (per UKHSA guidance).
• Vaccination: MenB (infants) + MenACWY (teenagers and at-risk groups).

💡 Exam pearl: Meningococcal rash = non-blanching petechiae/purpura. Immediate benzylpenicillin pre-hospital. In hospital: Ceftriaxone is first line.