Pertussis – infant — RACP Paediatrics MCQ

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ModerateRespiratoryPertussis – infantRACP Paediatrics

A 4-week-old unvaccinated infant presents with 5 days of paroxysmal cough with post-tussive vomiting and apnoeic episodes. Lymphocyte count is 25 × 10⁹/L. Pertussis PCR is positive. What is the most appropriate antibiotic?

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Correct answer: B — Azithromycin

Azithromycin is the first-line treatment for pertussis in infants, especially those <1 month (where erythromycin is associated with pyloric stenosis). Treatment within the first 3 weeks of cough onset reduces transmission but may not alter clinical course. Young infants with pertussis require hospital admission for monitoring of apnoeas.

Reference: Australian Therapeutic Guidelines – 2024 – Antibiotic; RCH Melbourne – 2023 – Pertussis CPG