Neisseria meningitidis

Background

Microbiology

• Gram-negative diplococcus in the genus Neisseria
• Traditionally organized by serogroups of capsular polysaccharide
  • A, B, C, E, H, I/K, L/ W, X, Y, and Z are confirmed genetically

Epidemiology

• Six serogroups cause essentially all disease: A, B, C, W, X, and Y
• In Canada, serogroups B, C, W-135 and Y are the most common causes, with B being the most commonly reported
  • Historically, B caused the majority of sporadic cases, and virulent serogroup C caused the majority of outbreaks
• In African meningitis belt, serogroups A, C, W-135, and X are most common

Risk Factors

• Living in African meningitis belt during an epidemic
• Participating in Hajj pilgrimage
• Living in student dormitories
• Living in military barracks

Clinical Manifestations

• The most common manifestation is bacterial meningitis
  • May have petechial or purpuric rash
• The most common non-neurological manifestation is community-acquired pneumonia1
• Other respiratory tract manifestations include otitis media and acute epiglottitis
• Can cause either acute or chronic bacteremia, with or without severe sepsis, Waterhouse-Friderichsen syndrome, and purpura fulminans
• May present with petechial rash, occasionally pustular, and may be confused for Rocky Mountain spotted fever or gonorrhea
• Can occasionally cause urethritis, especially in men who have sex with men
• Rarely causes pericarditis, septic arthritis, and conjunctivitis

Management

• For meningitis: ceftriaxone 2 g IV q12h or penicillin G for 7 days (5 days in UK)
  • Alternatives include chloramphenicol, aztreonam, and meropenem
• Others: ceftriaxone, penicillin or ampicillin (if susceptible), ciprofloxacin, levofloxacin, moxifloxacin, azithromycin
  • Increasing (though still low) ampicillin and penicillin resistance

Prevention

• Chemoprophylaxis of close contacts is indicated to prevent disease regardless of immunization status
  • Close contacts include: household contacts; people who share sleeping arrangements; people who have direct contamination of nose or mouth with the case; children and childcare staff; airline passengers sitting immediately to the left and right if flight was at least 8 hours
  • Not usually for healthcare contacts, unless intensive unprotected contact such as intubation or resuscitation without PPE
  • Exposures within 7 days before symptoms to 24 hours after appropriate antibiotics
  • Ideally within 24 hours, but up to 10 days (end of incubation period) after last contact with the case
• Choice of chemoprophylaxis
  • For adults: ciprofloxacin 500 mg PO once or rifampin 600 mg PO q12h for four doses
  • For children: rifampin 5 mg/kg (<1 month) to 10 mg/kg (≥1 month, max 600 mg) PO q12h for 4 doses
  • Alternative: ceftriaxone 125 mg (<12 years) to 250 mg (≥12 years) IM once
• Also vaccination, for all close contacts except airplane and healthcare