What is the recommended management for a patient with pertussis?

Management of Pertussis

Immediate Antibiotic Treatment

Azithromycin is the first-line antibiotic for pertussis treatment across all age groups, and treatment should be initiated immediately upon clinical suspicion without waiting for laboratory confirmation. 1

Age-Specific Azithromycin Dosing

• Infants <6 months: 10 mg/kg/day for 5 consecutive days 1
• Infants ≥6 months and children: 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg/day (maximum 250 mg) on days 2-5 1
• Adults: 500 mg on day 1, followed by 250 mg/day on days 2-5 1, 2

Alternative Antibiotic Options

• Clarithromycin: 500 mg twice daily for 7 days in adults; equally effective as azithromycin with comparable tolerability 1, 2
• Trimethoprim-sulfamethoxazole (TMP-SMZ): Reserved for patients >2 months with macrolide contraindications or hypersensitivity 1, 2
• Erythromycin: 40-50 mg/kg/day in children or 1-2 g/day in adults for 14 days; avoid in infants <6 months due to infantile hypertrophic pyloric stenosis (IHPS) risk 1, 3

Critical Timing Considerations

Early treatment during the catarrhal phase (first 2 weeks) can reduce symptom duration and severity by approximately 50%, while late treatment (paroxysmal phase, >3 weeks) provides limited clinical benefit to the patient but remains essential for preventing transmission. 1, 2

• Antibiotics rapidly clear B. pertussis from the nasopharynx regardless of when treatment begins 1, 4
• Approximately 80-90% of untreated patients spontaneously clear the organism within 3-4 weeks from cough onset 1
• The primary goal of antibiotic therapy is eradicating the organism and reducing transmission, not shortening disease duration in established cases 4

Infection Control Measures

Isolate patients at home and away from work/school for 5 days after starting antibiotics; if antibiotics cannot be administered, isolation should continue for 21 days after cough onset. 1, 2

• Pertussis has a secondary attack rate exceeding 80% among susceptible household contacts 1, 2
• Vaccinated individuals with breakthrough infections can still transmit disease to others 4

Postexposure Prophylaxis for Contacts

All household and close contacts require macrolide antibiotic prophylaxis using the same regimens as treatment, regardless of age or vaccination status. 1, 4, 2

Priority Groups for Prophylaxis

• Infants <12 months 1, 2
• Pregnant women in the third trimester 1, 2
• Healthcare workers with known exposure 1
• All household contacts when exposure settings include vulnerable individuals 1

Prophylaxis should be administered within 21 days of exposure 2

Therapies to Avoid

Do not use β-agonists, antihistamines, corticosteroids, or pertussis immunoglobulin—these have no proven benefit in controlling coughing paroxysms or improving clinical outcomes. 1, 4, 2

Important Medication Considerations and Precautions

• Azithromycin: Do not administer simultaneously with aluminum- or magnesium-containing antacids as they reduce absorption 1, 2
• Azithromycin: Use caution in patients with impaired hepatic function 1, 2
• Azithromycin: Obtain baseline ECG to exclude QTc prolongation in patients taking citalopram or other QTc-prolonging medications 1
• Erythromycin and clarithromycin (NOT azithromycin): Inhibit cytochrome P450 enzyme system and may interact with digoxin, triazolam, and ergot alkaloids 1
• Macrolides: Contraindicated in patients with history of hypersensitivity to any macrolide agent 1

Vaccination Considerations

• Neither vaccination nor natural disease provides lifelong immunity; vaccine immunity wanes 5-10 years post-vaccination 1, 4
• Vaccination reduces disease duration and severity by approximately 50% in breakthrough infections 4
• Vaccinated children often present with atypical symptoms, potentially lacking the characteristic "whoop" 4
• Do not dismiss pertussis based solely on vaccination status—breakthrough infections occur and should be actively considered 4

Monitoring for Complications

Watch for the following complications, particularly in infants and elderly patients:

• Common: Weight loss, sleep disturbance, post-tussive vomiting 4, 2
• Pressure-related effects: Pneumothorax, epistaxis, subconjunctival hemorrhage, rib fractures 4, 2
• Infectious complications: Primary or secondary bacterial pneumonia, otitis media 4
• Serious (rare): Seizures, hypoxic encephalopathy requiring immediate evaluation 4

Common Pitfalls to Avoid

• Do not delay treatment waiting for laboratory confirmation—clinical suspicion alone warrants immediate antibiotic initiation 1, 2
• Do not assume treatment is futile in the paroxysmal stage—while clinical benefit to the patient may be limited, treatment remains essential to prevent transmission 2
• Do not assume typical "whooping" presentation—vaccinated children and adults often have atypical symptoms 4