What is the recommended chemoprophylaxis for close contacts of a confirmed Neisseria meningitidis serogroup B infection?

Meningococcal Serogroup B Prophylaxis

All close contacts of confirmed or probable Neisseria meningitidis serogroup B infection should receive ciprofloxacin as first-line chemoprophylaxis: 500 mg orally as a single dose for adults, 250 mg for children aged 5-12 years, and 30 mg/kg (maximum 125 mg) for children under 5 years. 1, 2, 3

Who Qualifies as a Close Contact

Close contacts requiring prophylaxis include 3:

• Household members who lived with the patient during the 7 days before symptom onset
• Intimate kissing contacts
• Anyone with direct exposure to oral secretions (e.g., mouth-to-mouth resuscitation, airway management without mask protection)
• Child-care center attendees exposed to the case
• Healthcare personnel who managed the patient's airway or were exposed to respiratory secretions without appropriate protection
• Airline passengers seated directly adjacent to the index patient on flights ≥8 hours

The rationale for aggressive prophylaxis is compelling: secondary attack rates among close contacts are 2-4 per 1,000 population—a 1,000-fold increase over the baseline adult incidence of 0.23 per 100,000. 1, 3 Most invasive disease is acquired within 7 days preceding symptom onset. 1, 3

Antibiotic Regimens

First-Line: Ciprofloxacin (Preferred)

Ciprofloxacin is now recommended over rifampicin because it is a single dose and readily available. 1, 3 Dosing:

• Adults: 500 mg orally, single dose 1, 3
• Children 5-12 years: 250 mg orally, single dose 1, 3
• Children <5 years: 30 mg/kg (maximum 125 mg) orally, single dose 1, 3

Important caveat: In areas where ≥2 ciprofloxacin-resistant meningococcal cases have been reported AND ≥20% of all invasive cases in the past 12 months are ciprofloxacin-resistant, alternative antibiotics should be preferentially considered. 4 Ciprofloxacin resistance, while historically rare, has been increasing since 2019 in the United States. 4

Alternative: Rifampicin (2-day course)

Use when ciprofloxacin is contraindicated or in areas with documented ciprofloxacin resistance 1, 2, 3:

• Adults and children >12 years: 600 mg twice daily for 2 days 1, 2, 3
• Children 1-12 years: 10 mg/kg twice daily for 2 days 1, 2, 3
• Infants <12 months: 5 mg/kg twice daily for 2 days 1, 2, 3

Critical warning: Rifampicin is contraindicated during the first trimester of pregnancy and reduces oral contraceptive efficacy. 3 Additionally, rifampicin resistance can develop rapidly—in one outbreak study, 12% of isolates developed resistance after mass prophylaxis. 5

Alternative: Ceftriaxone (Single intramuscular dose)

Particularly useful during pregnancy as first choice 2, 3:

• Adults: 250 mg IM, single dose 2, 3
• Children <15 years: 125 mg IM, single dose 2, 3

Timing and Administration

Prophylaxis must be initiated within 24 hours of case identification for maximal effectiveness. 3 Administration more than 14 days after exposure provides limited or no benefit. 3 Do not delay treatment awaiting culture results, as oropharyngeal cultures do not alter management decisions. 3

Coordination with Public Health

Prophylaxis should be initiated by public health authorities (Communicable Disease Control teams), not by admitting clinicians, although clinicians may be asked to arrange prescriptions. 1, 3 All meningococcal cases must be notified to the relevant public health authority—this is a legal requirement in most jurisdictions. 1, 3

Vaccination Considerations for Serogroup B

Unlike other meningococcal serogroups, routine vaccination is NOT recommended for contacts of a single serogroup B case. 1 However:

If ≥2 serogroup B cases occur within the same household, serogroup B vaccination (Bexsero) should be offered to all household contacts in addition to chemoprophylaxis, even if the interval between cases exceeds 30 days or the strains are subsequently identified as different. 1, 3, 6

This recommendation differs from non-B serogroups, where unvaccinated contacts should receive appropriate vaccination after a single case. 1

Long-Term Risk Management

Even after appropriate chemoprophylaxis, close contacts retain an elevated risk for at least 6 months. 1, 3 Medical records of all close contacts should be flagged to alert future providers of this persistent increased risk. 1, 3

When Prophylaxis Is NOT Indicated

Do not provide prophylaxis for 3:

• Contacts of patients with N. meningitidis isolated only from non-sterile sites (oropharyngeal swabs, endotracheal secretions, conjunctival swabs)
• Asymptomatic nasopharyngeal carriers
• Casual contacts without direct exposure to oral secretions

Common Pitfalls

Avoid these errors:

• Delaying prophylaxis beyond 24 hours while awaiting confirmatory testing 3
• Failing to notify public health authorities immediately 1
• Prescribing prophylaxis for casual contacts who lack direct oral secretion exposure 3
• Using ciprofloxacin in areas with documented resistance patterns meeting the threshold criteria 4
• Forgetting that rifampicin reduces oral contraceptive efficacy 3
• Assuming prophylaxis eliminates all risk—contacts remain at elevated risk for 6 months 1, 3