What to do after exposure to Neisseria (N) meningitidis aerosol?

Management of Neisseria Meningitidis Aerosol Exposure

Immediate antimicrobial chemoprophylaxis is the primary intervention required after aerosol exposure to Neisseria meningitidis, ideally administered within 24 hours of exposure. 1

Indications for Prophylaxis

Prophylaxis is indicated for:

• Persons who have had intensive, unprotected contact (without wearing a mask) with infected patients
• Those exposed to respiratory secretions through procedures such as intubation, resuscitation, or examination of the oropharynx 2
• Laboratory personnel exposed to aerosolized N. meningitidis 1

Recommended Antimicrobial Agents

First-line options:

1. Ciprofloxacin

   • Adults: 500 mg orally as a single dose
   • Children 5-12 years: 250 mg orally as a single dose
   • Children <5 years: 30 mg/kg orally as a single dose (max 125 mg)
   • Not recommended for infants <1 year
   • 90-95% effective in reducing nasopharyngeal carriage 1
   • Note: In areas with documented ciprofloxacin resistance, alternative agents should be used 3

2. Rifampin

   • Adults: 600 mg orally twice daily for 2 days
   • Children: 10 mg/kg twice daily for 2 days
   • Infants <1 year: 5 mg/kg twice daily for 2 days
   • 90-95% effective in reducing nasopharyngeal carriage 2, 1
   • Caution: Not recommended for pregnant women due to teratogenicity in laboratory animals 2
   • Note: FDA-approved specifically for elimination of meningococci from the nasopharynx 4

3. Ceftriaxone

   • Adults: 250 mg IM as a single dose
   • Children and infants: 125 mg IM as a single dose
   • 90-95% effective in reducing nasopharyngeal carriage 2, 1
   • Safe for use during pregnancy 2

Alternative option:

• Azithromycin: Has been reported effective as a single 500 mg oral dose for eradicating nasopharyngeal carriage 2, 3

Timing of Prophylaxis

• Administer as soon as possible, ideally within 24 hours after identification of exposure 2, 1
• Prophylaxis administered >14 days after exposure has limited or no value 1

Additional Considerations

1. Nasopharyngeal cultures:

   • Not helpful in determining the need for prophylaxis
   • May unnecessarily delay implementation of preventive measures 2, 1

2. Vaccination:

   • Not recommended for immediate post-exposure prophylaxis 2
   • Meningococcal vaccines (MenACWY) have limited benefit for post-exposure prophylaxis but may be considered in outbreak settings 2, 1

3. Resistance monitoring:

   • Resistance to recommended antibiotics remains uncommon in the US but is increasing globally 5, 6
   • Recent increases in ciprofloxacin-resistant strains in some areas of the US warrant consideration of alternative agents in these regions 3

4. Follow-up:

   • Close contacts remain at increased risk for up to 6 months and should be monitored accordingly 1

Common Pitfalls and Caveats

1. Delayed prophylaxis: Effectiveness decreases significantly if not administered within 24 hours of exposure 2

2. Reliance on vaccination alone: Vaccination is not a substitute for chemoprophylaxis in exposed individuals 2

3. Inappropriate antibiotic selection: Using antibiotics with known resistance patterns in your area can lead to prophylaxis failure 3

4. Incomplete contact identification: Ensure all persons with significant aerosol exposure are identified and treated 2

5. Rifampin resistance development: Using rifampin during outbreaks may lead to circulation of resistant isolates; consider alternative agents in such settings 7

6. Pregnancy considerations: Avoid rifampin in pregnant women; ceftriaxone is the preferred agent 2

By following these evidence-based recommendations, the risk of developing invasive meningococcal disease after aerosol exposure can be significantly reduced.