What is the recommended treatment for pertussis?

Treatment for Pertussis

First-Line Antibiotic Therapy

Azithromycin is the preferred first-line antibiotic for treating pertussis across all age groups due to its superior tolerability, convenient dosing, and equivalent efficacy to erythromycin. 1

Age-Specific Azithromycin Dosing

Infants < 6 months:

• 10 mg/kg per day for 5 consecutive days 1
• Azithromycin is specifically preferred in infants < 1 month due to significantly lower risk of infantile hypertrophic pyloric stenosis (IHPS) compared to erythromycin 1

Infants ≥ 6 months and children:

• 10 mg/kg (maximum 500 mg) on day 1
• Followed by 5 mg/kg per day (maximum 250 mg) on days 2-5 1

Adults:

• 500 mg on day 1
• Followed by 250 mg per day on days 2-5 1

Alternative First-Line Option: Clarithromycin

Clarithromycin is equally effective as azithromycin and can be used as an alternative first-line agent, particularly in infants 1-5 months of age, based on in vitro effectiveness and safety profile 1. Research demonstrates 100% microbiologic eradication with 7-day clarithromycin regimens 2.

Alternative Therapy for Macrolide Contraindications

For patients > 2 months with macrolide allergies or contraindications:

• Trimethoprim-sulfamethoxazole (TMP-SMZ) is the recommended alternative 1
• Macrolides are contraindicated in patients with history of hypersensitivity to any macrolide agent 1

Timing of Treatment: Critical for Effectiveness

Start antibiotics immediately upon clinical suspicion without waiting for culture confirmation 1. The effectiveness of treatment is highly dependent on timing:

Early treatment (catarrhal phase, first 2 weeks):

• Rapidly clears B. pertussis from the nasopharynx 1
• Reduces duration and severity of symptoms 1
• Decreases coughing paroxysms 1
• Lessens the period of communicability 1

Late treatment (paroxysmal phase, > 3 weeks):

• Limited clinical benefit for the patient 1
• Still indicated to prevent transmission to others 1
• Approximately 80-90% of untreated patients will spontaneously clear the organism within 3-4 weeks from cough onset 1

Infection Control Measures

Isolate patients at home and away from work/school for 5 days after starting antibiotics to prevent transmission 1.

Important Administration Precautions

• Do not administer azithromycin with aluminum- or magnesium-containing antacids as they reduce absorption 1
• Use azithromycin with caution in patients with impaired hepatic function 1
• Monitor for drug interactions with agents metabolized by cytochrome P450 (e.g., digoxin, triazolam, ergot alkaloids) 1

Erythromycin: When It Must Be Used

If erythromycin must be used despite its limitations 3:

Dosing:

• Children: 40-50 mg/kg/day in divided doses for 14 days 1, 3
• Adults: 1-2 g per day in divided doses for 14 days 1, 3

Critical warning: Erythromycin is associated with IHPS in infants < 1 month and should be avoided if possible 1. Erythromycin resistance remains rare (< 1%) 1.

Comparative Efficacy Evidence

Azithromycin and clarithromycin demonstrate equivalent microbiologic eradication rates to erythromycin (96-100%) but with significantly better tolerability 1, 2. Compliance rates are dramatically higher with azithromycin (93%) compared to erythromycin (57%), primarily due to fewer gastrointestinal side effects 4.

Postexposure Prophylaxis

Use the same antimicrobial agents and dosing regimens for postexposure prophylaxis as for treatment 1. Prophylaxis should be prioritized for:

• Close contacts in exposure settings with infants < 12 months 1
• Close contacts of women in the third trimester of pregnancy 1

Ineffective Therapies to Avoid

Long-acting β-agonists, antihistamines, corticosteroids, and pertussis immunoglobulin have no significant benefit in controlling coughing paroxysms 1.