What is the most appropriate management for a patient with a several-day history of cough, cyanosis, post-tussive vomiting, and lymphocytosis?

Management of Suspected Pertussis

The most appropriate management is A. Azithromycin. This patient presents with classic pertussis (whooping cough): paroxysmal cough with post-tussive vomiting, cyanotic episodes, and marked lymphocytosis (80% of 27 × 10^9/L = 21.6 × 10^9/L lymphocytes), and macrolide antibiotics should be initiated immediately without waiting for laboratory confirmation 1, 2.

Clinical Diagnosis

When a patient has cough lasting ≥2 weeks accompanied by paroxysms of coughing and post-tussive vomiting, the diagnosis of Bordetella pertussis infection should be made unless another diagnosis is proven 1. The clinical presentation here is pathognomonic:

• Paroxysmal cough with post-tussive vomiting 1
• Episodes of cyanosis (highly specific for pertussis in young patients) 3, 4, 5
• Marked leukocytosis with absolute lymphocytosis (>10 × 10^9/L lymphocytes) 4, 5, 6
• This triad of cyanosis and lymphocytosis are independent predictors for pertussis in children up to 6 months old 5

The lymphocytosis is caused by pertussis toxin and is a hallmark of severe disease 3, 4.

Immediate Treatment Algorithm

First-Line: Macrolide Antibiotic

Children and adult patients with confirmed or probable whooping cough should receive a macrolide antibiotic immediately because early treatment within the first few weeks will diminish coughing paroxysms and prevent spread of disease 1.

• Azithromycin is the preferred first-line treatment due to better side effect profile and compliance 2
• Treatment should be started immediately without waiting for culture results 1, 2, 7
• Patient isolation for 5 days from the start of antibiotic treatment is mandatory to prevent transmission 1, 2
• Early treatment (within first 2 weeks) decreases paroxysms and prevents transmission; treatment beyond this period may be offered but response is unlikely 1

Diagnostic Confirmation (Do Not Delay Treatment)

While treatment should begin immediately, obtain nasopharyngeal aspirate or Dacron swab for B. pertussis culture to confirm diagnosis 1. Isolation of bacteria is the only certain way to make the diagnosis 1.

Why Other Options Are Incorrect

B. Ceftriaxone - Incorrect

Ceftriaxone has no role in pertussis treatment 1. Pertussis requires macrolide antibiotics specifically (erythromycin, azithromycin, or clarithromycin) 1, 2. Beta-lactams like ceftriaxone are ineffective against B. pertussis and would only be appropriate if bacterial pneumonia from another pathogen (e.g., S. pneumoniae) were suspected, which is not supported by this presentation 1.

C. Nebulized Salbutamol - Incorrect

Long-acting β-agonists should not be offered to patients with whooping cough because there is no evidence that they benefit these patients 1. While bronchodilators might seem intuitive for cough, they have been specifically studied and found ineffective in pertussis 1.

D. Corticosteroids - Incorrect

Corticosteroids should not be offered to patients with whooping cough because there is no evidence that they benefit these patients 1. In fact, steroids can be detrimental in severe pertussis, particularly in young infants with leukocytosis and pulmonary complications 3.

Corticosteroids are only considered for severe paroxysms of post-infectious cough (not pertussis) when other common causes have been ruled out 1. The distinction is critical: this guideline explicitly states corticosteroids are for postinfectious cough "not due to bacterial sinusitis or early on in a Bordetella pertussis infection" 1.

Critical Pitfalls to Avoid

• Do not wait for laboratory confirmation to start macrolide treatment - delay decreases effectiveness as antibiotics only work if given within the first few weeks 1, 2, 7
• Do not forget isolation precautions - patient is contagious until 5 days after starting antibiotics 1, 2, 7
• Do not use corticosteroids or beta-agonists - these have no benefit and steroids may be harmful in severe pertussis with leukocytosis 1, 3
• Recognize that severe pertussis with high leukocyte counts can lead to pulmonary hypertension and death - the leukocytosis itself is pathogenic due to pertussis toxin causing leukocyte aggregation in pulmonary vessels 3, 4

Symptomatic Management (Adjunctive Only)

If severe paroxysms persist despite antibiotic therapy, consider ipratropium inhalation as first-line symptomatic treatment for cough suppression 1, 2. Central-acting antitussives like dextromethorphan (60 mg optimal dose) should only be considered when other measures fail 1, 2.