What is the treatment for a patient who has tested positive for Bordetella (B) pertussis?

Treatment for Bordetella pertussis Infection

Patients who test positive for Bordetella pertussis should be treated with a macrolide antibiotic, with azithromycin being the preferred first-line treatment due to its effectiveness in bacterial eradication, better side effect profile, and improved compliance compared to erythromycin. 1

First-Line Treatment Options

Azithromycin (Preferred)

• Adults: 500 mg on day 1, then 250 mg daily for 4 days (5 days total) 2, 1
• Children: 10 mg/kg on day 1, then 5 mg/kg daily for 4 days (5 days total) 2, 1
• Infants < 6 months: 10-12 mg/kg/day for 5-7 days 2

Clarithromycin

• Adults: 500 mg twice daily for 7 days (1 g/day total) 2, 1
• Children > 1 month: 15 mg/kg/day in 2 divided doses for 7 days (maximum 1 g/day) 2
• Infants < 1 month: Not recommended 2

Erythromycin

• Adults: 500 mg four times daily or 333 mg delayed-release tablets three times daily for 14 days 2
• Children: 40-50 mg/kg/day divided into 4 doses for 14 days 2
• Note: Less preferred due to higher incidence of gastrointestinal side effects and longer treatment duration 1, 3

Alternative Treatment (for macrolide intolerance or allergy)

Trimethoprim-Sulfamethoxazole (TMP-SMZ)

• Adults: Trimethoprim 320 mg/day, sulfamethoxazole 1,600 mg/day in 2 divided doses for 14 days 2
• Children > 2 months: Trimethoprim 8 mg/kg/day, sulfamethoxazole 40 mg/kg/day in 2 divided doses for 14 days 2
• Infants < 2 months: Contraindicated 2

Treatment Timing and Effectiveness

• Treatment is most effective when initiated during the catarrhal phase (first 1-2 weeks of illness) 2, 1
• Early treatment can:
  • Rapidly clear B. pertussis from the nasopharynx
  • Decrease coughing paroxysms
  • Reduce complications
  • Limit transmission to others 2, 1
• Treatment during the paroxysmal phase may be of limited benefit but is still recommended 2

Infection Control Measures

• Patients should be isolated at home and away from work or school for 5 days after starting antibiotic therapy 2, 1
• Healthcare workers with pertussis should be restricted from work during the first 5 days of antimicrobial therapy 2
• If unable to take antimicrobial treatment, isolation should continue for 21 days after onset of cough 2

Important Clinical Considerations

• Antibiotic resistance: Macrolide-resistant B. pertussis is rare 2
• Duration of therapy: While shorter courses (5-7 days) of azithromycin or clarithromycin are generally effective, some young unvaccinated infants may require longer treatment as they can remain PCR-positive after a standard course 4
• Monitoring: Patients should be monitored for improvement in symptoms and potential side effects of antibiotics
• Complications: Severe coughing can lead to pneumothorax, rib fracture, epistaxis, subconjunctival hemorrhage, and other complications 1

Prophylaxis for Close Contacts

• Close contacts should receive the same antibiotic regimens as for treatment, regardless of vaccination status 2, 1
• Prophylaxis is most effective when initiated within 2 weeks of exposure 2

Diagnostic Confirmation

• Nasopharyngeal aspirate or Dacron swab for culture is the definitive diagnostic method 2
• PCR testing may be used but lacks standardized validation 2
• Paired acute and convalescent sera showing fourfold increase in IgG or IgA antibodies to pertussis toxin (PT) or filamentous hemagglutinin (FHA) can support diagnosis 2

By following these evidence-based treatment guidelines, clinicians can effectively manage B. pertussis infections while minimizing transmission and reducing complications.