What is the recommended treatment for a baby with pertussis (whooping cough)?

Treatment of Pertussis in Infants

Azithromycin is the first-line treatment for pertussis (whooping cough) in babies due to its effectiveness, better tolerability, and lower risk of infantile hypertrophic pyloric stenosis compared to other macrolides. 1

First-Line Treatment Recommendations

For Infants Under 1 Month

• Azithromycin is the recommended first-line agent by the Centers for Disease Control and Prevention for infants less than 1 month of age 1
• Dosing: 10 mg/kg/day for 5 days 1
• Azithromycin is preferred over erythromycin due to significantly lower risk of infantile hypertrophic pyloric stenosis (IHPS) 1, 2

For Infants 1-5 Months

• Both azithromycin and clarithromycin are recommended as first-line agents by the American Academy of Pediatrics 1
• Azithromycin dosing: 10 mg/kg/day for 5 days 1
• Clarithromycin is an alternative but azithromycin has better tolerability 1, 3

For Infants ≥6 Months

• 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

Efficacy and Safety Considerations

• Azithromycin has demonstrated 100% bacterial eradication rates in clinical studies, equal to erythromycin but with significantly fewer side effects 3
• Gastrointestinal adverse events occur less frequently with azithromycin (18.8%) compared to erythromycin (41.2%), including less nausea, vomiting, and diarrhea 3
• Compliance with azithromycin therapy (90%) is significantly better than with erythromycin (55%), improving overall treatment effectiveness 3
• Erythromycin has been associated with infantile hypertrophic pyloric stenosis in neonates, with a dose-response relationship showing 5.1% risk for 8-14 days of treatment and 10% risk for 15-21 days 4

Alternative Treatment Options

• For patients older than 2 months with macrolide contraindications, trimethoprim-sulfamethoxazole (TMP-SMZ) can be used as an alternative agent 1
• Erythromycin is effective but requires four divided daily doses for 14 days, making compliance difficult 2, 4

Important Precautions

• Macrolides are contraindicated in patients with history of hypersensitivity to any macrolide agent 1
• Azithromycin should not be taken with aluminum- or magnesium-containing antacids as they reduce absorption 1, 5
• Use azithromycin with caution in patients with impaired hepatic function 1, 4
• Monitor for potential drug interactions with agents metabolized by cytochrome P450 enzyme system (e.g., digoxin) 1

Treatment Timing and Effectiveness

• Antibiotics administered early in the course of illness can reduce duration and severity of symptoms and lessen the period of communicability 1
• Treatment is most effective when initiated during the catarrhal phase, with limited effect on established paroxysms, emesis, or apnea if given during later phases 3, 6
• Approximately 80-90% of patients with untreated pertussis will spontaneously clear B. pertussis from the nasopharynx within 3-4 weeks from onset of cough 1

Postexposure Prophylaxis

• The same antimicrobial agents and dosing regimens used for treatment are recommended for postexposure prophylaxis 1
• Prophylaxis should be administered to close contacts, especially in exposure settings that include infants <12 months or women in the third trimester of pregnancy 1