What is the most appropriate therapy for a 44‑year‑old woman with a two‑week paroxysmal cough after an upper‑respiratory infection, clear lung exam and normal chest radiograph?

Azithromycin (Zithromax) is the most appropriate therapy for this patient with suspected pertussis

This 44-year-old woman presents with the classic clinical picture of pertussis: an initial upper respiratory prodrome followed by severe paroxysmal cough with post-tussive emesis lasting more than 2 weeks. 1

Why This is Pertussis Until Proven Otherwise

• The Centers for Disease Control and Prevention recommends excluding pertussis infection when cough lasts ≥2 weeks with paroxysms and post-tussive vomiting, which this patient clearly demonstrates 1
• The timeline is pathognomonic: 10 days of upper respiratory symptoms (catarrhal phase) followed by worsening paroxysmal cough (paroxysmal phase) 1
• Clear lung examination and normal chest radiograph do not exclude pertussis—in fact, they support it, as pertussis typically presents without focal findings 1
• The American Thoracic Society recommends starting antibiotics immediately upon clinical suspicion of pertussis, without waiting for culture confirmation 1

First-Line Treatment: Azithromycin

• The Centers for Disease Control and Prevention recommends azithromycin as the first-line agent for treatment of pertussis in adults, with a dosing regimen of 500 mg on day 1, followed by 250 mg per day on days 2-5 1
• Early treatment during the first 2 weeks rapidly clears B. pertussis from the nasopharynx, decreases coughing paroxysms, and reduces complications 1
• Even though the patient is beyond the optimal treatment window, antibiotics are still indicated to prevent transmission to others 1
• The American Academy of Pediatrics recommends isolating patients at home and away from work/school for 5 days after starting antibiotics to prevent transmission 1

Why the Other Options Are Wrong

Prednisone (Option 1)

• Prednisone is reserved only for severe paroxysms of postinfectious cough when other common causes have been ruled out, and only after pertussis has been excluded 2
• The Infectious Diseases Society of America states that corticosteroids have no significant benefit in controlling coughing paroxysms in pertussis 1

Antihistamine (Option 2)

• The Infectious Diseases Society of America explicitly states that antihistamines have no significant benefit in controlling coughing paroxysms in pertussis 1
• Antihistamines are appropriate for upper airway cough syndrome, not for pertussis 2

Inhaled Beta-Agonist (Option 3)

• The Infectious Diseases Society of America states that long-acting β-agonists have no significant benefit in controlling coughing paroxysms in pertussis 1
• Beta-agonists would be appropriate for asthma or postinfectious cough with bronchospasm, neither of which fits this presentation 2

Immunoglobulin Infusion (Option 4)

• The Infectious Diseases Society of America states that pertussis immunoglobulin has no significant benefit in controlling coughing paroxysms 1
• This intervention has no role in routine pertussis management 1

Critical Next Steps

• Obtain a nasopharyngeal aspirate or Dacron swab for culture to confirm B. pertussis, as isolation of the bacteria is the only certain way to make the diagnosis 1
• Verify and update the patient's vaccination status and ensure all household contacts are up to date with pertussis vaccination 1
• Administer the same antimicrobial regimen (azithromycin) for postexposure prophylaxis to close contacts, especially if exposure settings include infants <12 months or women in the third trimester of pregnancy 1
• The patient should be isolated at home for 5 days after starting antibiotics 1

Common Pitfall to Avoid

• Do not dismiss this as simple "postinfectious cough" and prescribe ipratropium or supportive care alone—the paroxysmal nature with post-tussive vomiting at 2+ weeks mandates treatment for pertussis 1, 2
• Approximately 80-90% of patients with untreated pertussis will spontaneously clear B. pertussis from the nasopharynx within 3-4 weeks from onset of cough, but treatment is still required to prevent transmission 1