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Difficulty: MediumPediatric Infectious Diseases

An unvaccinated 14-month-old female toddler is evaluated in the outpatient clinic in late autumn. She has a medical history of tetralogy of Fallot and 22q11.2 deletion syndrome (DiGeorge syndrome). Her parents report she has been experiencing intense, exhausting bouts of coughing for the past four days. These episodes are often followed by a high-pitched inspiratory sound and occasional vomiting. Two weeks prior, she had mild nasal congestion and a low-grade temperature that seemingly resolved. Her temperature is 37.1∘C37.1^\circ\text{C} (98.8∘F98.8^\circ\text{F}), heart rate is 145/min145/\text{min}, and respiratory rate is 42/min42/\text{min}. On physical examination, the toddler appears fatigued. There are scattered, pinpoint, non-blanching red macules on her face and neck. Lung auscultation is clear between the coughing spasms.

Which of the following is the most appropriate next step in management?

  1. A
    Prescribe a course of oral amoxicillin-clavulanate
  2. B
    Administer a trial of nebulized albuterol
  3. Prescribe a course of oral azithromycinAnswer
  4. D
    Administer the live-attenuated measles, mumps, and rubella vaccine
  5. E
    Prescribe empiric intravenous ceftriaxone

Answer

The most appropriate next step is to prescribe a course of oral azithromycin.
The patient's clinical presentation of severe paroxysmal coughing spells followed by an inspiratory 'whoop' and post-tussive emesis in an unvaccinated child is a classic textbook description of pertussis (whooping cough), caused by Bordetella pertussis. The facial pinpoint macules are petechiae resulting from capillary rupture due to intense intrathoracic pressure generated during violent coughing. The most appropriate next step in management is to prescribe a macrolide antibiotic, such as oral azithromycin. While antibiotics administered during the paroxysmal phase may not significantly shorten the clinical course of the illness due to already established toxin-mediated ciliary damage, they remain crucial for rapidly eradicating nasopharyngeal carriage and preventing transmission to vulnerable contacts.

Step-by-Step Solution

1
Analyze the clinical presentation and vaccination status.
The unimmunized toddler presents with a triphasic illness (catarrhal phase followed by a paroxysmal phase with a 'whoop' and post-tussive emesis), which is highly characteristic of Bordetella pertussis infection.
Identifying the classic clinical syndrome of whooping cough is essential for selecting the correct targeted therapy.
2
Evaluate the physical examination findings.
The patient is fatigued with facial petechiae (pinpoint non-blanching macules) and clear lungs, which are expected complications of the severe increased intrathoracic pressure during coughing spasms rather than signs of a primary dermatologic or systemic bacterial process.
This confirms the diagnosis clinically and avoids unnecessary workup for alternative etiologies.
3
Determine the appropriate targeted pharmacotherapy.
The first-line treatment for B. pertussis is a macrolide antibiotic such as oral azithromycin.
Macrolides eradicate nasopharyngeal carriage, thereby reducing the transmission of the bacteria to susceptible contacts.
4
Rule out inappropriate interventions based on the patient's underlying comorbidities.
Live-attenuated vaccines (like MMR) are contraindicated because the patient has 22q11.2 deletion syndrome, which is associated with thymic hypoplasia and T-cell deficiency.
Administering a live vaccine to an immunocompromised patient can lead to severe disseminated infection.

Key Concept

Diagnosis and management of Bordetella pertussis (whooping cough) in an unimmunized patient, and recognizing contraindications to live vaccines in primary immunodeficiencies.
Estimated Time:1m 15s
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Topics

Pediatric Infectious Diseases

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