What is the recommended treatment for pertussis in adults?

Pertussis Treatment for Adults

For adults with pertussis, azithromycin 500 mg on day 1 followed by 250 mg daily on days 2-5 is the recommended first-line treatment. 1, 2

First-Line Antibiotic Therapy

Azithromycin is the preferred macrolide for treating pertussis in adults due to its convenient dosing schedule, better tolerability, and equivalent efficacy to other macrolides. 1, 2, 3

• Dosing regimen: 500 mg orally on day 1, then 250 mg daily on days 2-5 (total 5-day course). 1, 2
• Azithromycin should not be taken simultaneously with aluminum- or magnesium-containing antacids as they reduce absorption. 2
• Use with caution in patients with impaired hepatic function and monitor for potential drug interactions with agents metabolized by cytochrome P450 (e.g., digoxin, triazolam, ergot alkaloids). 2

Alternative First-Line Options

If azithromycin is unavailable or not tolerated, clarithromycin 1 g per day in two divided doses for 7 days is equally effective. 1, 2

• Clarithromycin inhibits the CYP3A enzyme system, requiring careful attention to drug interactions with medications like statins, benzodiazepines, and immunosuppressants. 1
• It is contraindicated with astemizole, cisapride, pimazole, or terfenadine due to risk of cardiac arrhythmias. 1

Erythromycin 1-2 g per day in divided doses for 14 days is another alternative, though less preferred due to higher rates of gastrointestinal side effects and lower compliance. 2, 4, 5

• Erythromycin has similar drug interaction concerns as clarithromycin and should not be used with the same contraindicated medications. 1
• Compliance rates with erythromycin are significantly lower (57%) compared to azithromycin (93%), primarily due to gastrointestinal upset. 5

Second-Line Therapy

For patients with macrolide contraindications or intolerance, trimethoprim-sulfamethoxazole (TMP-SMZ) is the recommended alternative: trimethoprim 320 mg per day plus sulfamethoxazole 1,600 mg per day in 2 divided doses for 14 days. 1, 2, 6

• TMP-SMZ is contraindicated in patients with known hypersensitivity to trimethoprim or sulfonamides. 1
• Use with caution in patients with impaired hepatic or renal function, folate deficiency, or blood dyscrasias, and in older adults due to higher risk of severe adverse events. 1
• Patients should maintain adequate fluid intake to prevent crystalluria and renal stones. 1
• Monitor for drug interactions with methotrexate, oral anticoagulants, antidiabetic agents, thiazide diuretics, and anticonvulsants. 1

Critical Timing Considerations

Start antibiotics immediately upon clinical suspicion without waiting for culture confirmation. 2

• Early treatment (catarrhal phase, first 2 weeks): Antibiotics can reduce duration and severity of symptoms and decrease the period of communicability. 2, 6
• Late treatment (paroxysmal phase, >3 weeks): Antibiotics have limited clinical benefit for symptom control but are still indicated to prevent transmission to others. 2
• Approximately 80-90% of untreated patients will spontaneously clear B. pertussis from the nasopharynx within 3-4 weeks from cough onset. 2

Isolation and Transmission Prevention

Isolate patients at home and away from work/school for 5 days after starting antibiotics to prevent transmission. 2

• The same antimicrobial regimens used for treatment are recommended for postexposure prophylaxis of close contacts. 2
• Prophylaxis is especially important for contacts in settings that include infants <12 months or women in the third trimester of pregnancy. 2

Ineffective Therapies

Do not use symptomatic treatments expecting clinical benefit: long-acting β-agonists, antihistamines, corticosteroids, and pertussis immunoglobulin have no significant benefit in controlling coughing paroxysms. 2

Common Pitfalls to Avoid

• Do not use ampicillin, amoxicillin, tetracyclines, fluoroquinolones, or cephalosporins for pertussis treatment—despite in vitro activity, these agents have not demonstrated clinical effectiveness and may fail to clear B. pertussis from the nasopharynx. 1
• Macrolide resistance in B. pertussis is rare (<1%), so resistance testing is not routinely necessary. 2
• All macrolides are contraindicated in patients with history of hypersensitivity to any macrolide agent. 1, 2