What is the treatment for pertussis?

Treatment for Pertussis

Macrolide antibiotics are the first-line treatment for pertussis, with azithromycin being the preferred agent due to better tolerability and shorter treatment duration compared to erythromycin. 1

Antimicrobial Treatment Options

First-line Agents (by Age Group)

For Infants <1 Month:

• Azithromycin: 10 mg/kg once daily for 5 days 1
  • Preferred agent due to lower risk of infantile hypertrophic pyloric stenosis (IHPS)
  • Erythromycin is not recommended in this age group

For Infants 1-5 Months:

• Azithromycin: 10 mg/kg once daily for 5 days 1
• Alternative: Erythromycin 40-50 mg/kg/day in 4 divided doses for 14 days (only if azithromycin unavailable)
  • Caution: Monitor for IHPS if erythromycin is used

For Infants ≥6 Months and Children:

• Azithromycin: 10 mg/kg (maximum: 500 mg) on day 1, followed by 5 mg/kg/day (maximum: 250 mg) on days 2-5 1
• Erythromycin: 40-50 mg/kg/day (maximum: 2 g/day) in 4 divided doses for 14 days 1

For Adults:

• Azithromycin: 500 mg on day 1, followed by 250 mg daily on days 2-5 1
• Erythromycin: 2 g/day in 4 divided doses for 14 days 1

Alternative Agent (for age ≥2 months):

• Trimethoprim-sulfamethoxazole (TMP-SMZ): Can be used when macrolides are contraindicated 1

Clinical Considerations

Timing of Treatment

• Antibiotics are most effective when administered during the early catarrhal phase 1
• Treatment during later stages (paroxysmal or convalescent) will still eradicate the organism but may not reduce symptoms 2

Goals of Treatment

1. Eradicate Bordetella pertussis from the nasopharynx
2. Reduce transmission to others
3. Potentially reduce severity and duration of symptoms if given early 1

Antibiotic Selection Factors

• Efficacy: All recommended macrolides effectively eradicate B. pertussis 1, 3
• Tolerability: Azithromycin and clarithromycin have fewer gastrointestinal side effects than erythromycin 1, 3
• Compliance: Shorter treatment courses and once-daily dosing improve adherence 1, 3
• Safety: Consider drug interactions and age-specific risks (e.g., IHPS in infants) 1, 4

Common Pitfalls and Caveats

1. IHPS Risk in Infants: Erythromycin use in infants <1 month significantly increases risk of IHPS. If erythromycin must be used in young infants, parents should be counseled about signs of IHPS (projectile vomiting, irritability with feeding) 1, 4

2. Drug Interactions: Erythromycin inhibits the cytochrome P450 enzyme system (CYP3A) and can interact with medications metabolized by this pathway. Azithromycin has fewer drug interactions 1, 4

3. Timing Limitations: Antibiotics have minimal effect on the clinical course if started after the catarrhal phase, but should still be given to reduce transmission 1, 2

4. Antacid Interactions: Advise patients not to take azithromycin with aluminum or magnesium-containing antacids as they reduce absorption 1

5. Treatment Failure: Approximately 80-90% of untreated patients will spontaneously clear B. pertussis within 3-4 weeks, but infants may remain culture-positive for >6 weeks 1

Post-exposure Prophylaxis

Post-exposure prophylaxis should be administered to:

• Household contacts of pertussis cases
• Individuals at high risk for severe disease (infants <12 months, pregnant women in third trimester)
• Individuals who may expose high-risk persons 1

The antimicrobial regimens for prophylaxis are identical to those used for treatment 1.

Supportive Care

In addition to antimicrobial therapy, supportive care is important, particularly for infants and young children who may experience:

• Paroxysmal coughing episodes
• Post-tussive vomiting
• Apnea (especially in infants)
• Weight loss and dehydration
• Sleep disturbance

Hospitalization may be required for infants and those with severe disease to monitor for complications and provide respiratory support if needed.