What is the recommended treatment for pertussis?

Treatment of Pertussis

Macrolide antibiotics are the first-line treatment for pertussis, with azithromycin being the preferred agent due to better tolerability, fewer side effects, and more convenient dosing compared to erythromycin. 1, 2

Age-Based Treatment Recommendations

Infants < 1 month

• First choice: Azithromycin 10 mg/kg once daily for 5 days 1
• Erythromycin and clarithromycin are NOT recommended due to risk of infantile hypertrophic pyloric stenosis (IHPS) 1
• Monitor infants for IHPS and other serious adverse events 1

Infants 1-5 months

• First choice: Azithromycin 10 mg/kg once daily for 5 days 1
• Alternative: Clarithromycin 15 mg/kg/day divided in two doses for 7 days 1, 3

Infants ≥6 months and children

• First choice: Azithromycin 10 mg/kg (maximum: 500 mg) on day 1, followed by 5 mg/kg per day (maximum: 250 mg) on days 2-5 1
• Alternatives:
  • Clarithromycin 15 mg/kg/day divided in two doses for 7 days (maximum: 1 g/day) 1, 3
  • Erythromycin 40-50 mg/kg/day divided in 4 doses for 14 days (maximum: 2 g/day) 1

Adults

• First choice: Azithromycin 500 mg on day 1, followed by 250 mg once daily on days 2-5 1, 4
• Alternatives:
  • Clarithromycin 1 g/day divided in two doses for 7 days 1
  • Erythromycin 2 g/day divided in 4 doses for 14 days 1

Alternative for macrolide allergy (patients ≥2 months)

• Trimethoprim-sulfamethoxazole (TMP-SMZ) 1, 4
  • Children: TMP 8 mg/kg/day, SMZ 40 mg/kg/day in 2 divided doses for 14 days
  • Adults: TMP 320 mg/day, SMZ 1600 mg/day in 2 divided doses for 14 days

Treatment Timing and Effectiveness

• Antibiotic treatment is most effective when initiated during the catarrhal stage (first 1-2 weeks) 1, 2
• Early treatment can reduce symptom severity and duration, and decrease the period of communicability 1, 2
• Treatment after 3 weeks of illness has limited benefit for symptom reduction but still eliminates bacterial carriage 1, 5
• Without treatment, 80-90% of patients will clear B. pertussis from the nasopharynx within 3-4 weeks, though untreated infants may remain culture-positive for >6 weeks 1, 2

Postexposure Prophylaxis

Postexposure prophylaxis should be administered to:

• All household contacts of a pertussis case, regardless of age or vaccination status 1
• Close contacts in settings that include:
  • Infants <12 months (especially <4 months) 1
  • Women in the third trimester of pregnancy 1
  • Immunocompromised individuals 4

The antimicrobial agents and dosing regimens for prophylaxis are the same as those for treatment 1.

Important Considerations and Caveats

• Timing is crucial: Treatment effectiveness diminishes significantly after the catarrhal stage 1, 2
• Treatment limitations: Antibiotics primarily prevent transmission rather than modify the course of established disease 4
• Monitoring young infants: Infants <1 month should be monitored for IHPS after macrolide treatment 1
• Persistent positivity: Some young infants may remain PCR-positive despite 7 days of treatment, potentially requiring extended therapy 6
• Drug interactions: Erythromycin and clarithromycin (but not azithromycin) inhibit the cytochrome P450 enzyme system and can interact with other medications 1
• Vaccination: While not directly therapeutic, maintaining high vaccination coverage is the most effective prevention strategy 1, 2

Supportive Care

• Hospitalization for infants <6 months or patients with severe disease 5
• Respiratory support as needed 5
• Adequate hydration and nutrition 5
• Avoidance of cough triggers 5

By following these treatment guidelines, clinicians can effectively manage pertussis cases while reducing transmission and preventing complications, particularly in vulnerable populations such as young infants.