Treatment of Pertussis (Whooping Cough) Infection
Macrolide antibiotics are the treatment of choice for pertussis infection, with azithromycin being preferred due to better tolerability, fewer side effects, and shorter treatment duration compared to erythromycin. 1
First-Line Treatment Options
Preferred Antimicrobial Agents by Age Group:
Infants <1 month:
- Azithromycin is preferred 1
- Erythromycin and clarithromycin are not recommended due to risk of infantile hypertrophic pyloric stenosis
Persons >1 month:
- Azithromycin, clarithromycin, or erythromycin can be used 1
- Azithromycin and clarithromycin are better tolerated than erythromycin
Alternative for persons >2 months:
- Trimethoprim-sulfamethoxazole (TMP-SMZ) if macrolides cannot be used 1
Specific Dosing Recommendations
Azithromycin (Preferred Agent):
- <6 months: 10 mg/kg/day for 5 days
- ≥6 months: 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) on days 2-5
Clarithromycin:
- 15 mg/kg/day in 2 divided doses (max 1 g/day) for 7 days
Erythromycin:
- 40-50 mg/kg/day in 4 divided doses (max 2 g/day) for 14 days 1
- Note: 7-day course of erythromycin estolate has been shown to be as effective as 14 days in one study 2, but guidelines still recommend 14 days
Timing and Expected Outcomes
Treatment should begin as soon as pertussis is suspected, without waiting for laboratory confirmation 1
Early treatment during the catarrhal phase (first 2 weeks) will:
- Rapidly clear B. pertussis from the nasopharynx
- Decrease coughing paroxysms
- Reduce complications
- Lessen period of communicability 1
Treatment during the paroxysmal phase may be less effective but should still be offered 1
Isolation Recommendations
- Patients should be isolated for 5 days from the start of antibiotic treatment 1
- Without treatment, patients may remain contagious for up to 3-4 weeks from cough onset 1
Important Clinical Considerations
- Antibiotic treatment is intended primarily to prevent transmission rather than to improve symptoms in the already infected patient 3
- Recent evidence suggests that young unvaccinated infants may remain PCR-positive despite 7 days of clarithromycin treatment, challenging the assumption that contagiousness ends after 5 days of antibiotics 4
- Adjunctive treatments (long-acting β-agonists, antihistamines, corticosteroids, pertussis Ig) have shown no significant benefit in controlling coughing paroxysms and are not recommended 1
Prophylaxis for Close Contacts
- Macrolide antibiotics should be administered to close contacts of pertussis cases
- Same agents and dosing as for treatment
- Particularly important for:
- Household contacts
- Infants and their household members
- Pregnant women in third trimester
- Immunocompromised individuals
- Those in close contact with high-risk individuals 3
Prevention
- Vaccination remains the most effective prevention strategy
- Tdap vaccine is recommended for:
- All children as part of routine vaccination
- Adolescents aged 11-18 years
- Adults up to age 65
- Pregnant women between 27-36 weeks gestation with each pregnancy 1
Remember that while antibiotics can prevent transmission, they have limited effect on the course of illness once coughing paroxysms have begun. Early diagnosis and treatment are crucial for reducing transmission and improving outcomes.