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Pertussis — RACP Paediatrics MCQ

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ModerateInfectious DiseasePertussisRACP Paediatrics

A 5-month-old girl presents with 3 weeks of paroxysmal coughing followed by an inspiratory whoop and post-tussive vomiting. She has had 2 apnoeic episodes. She has received only her birth hepatitis B vaccine but no other NIP vaccines. Which organism is most likely responsible?

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Correct answer: D — Bordetella pertussis

Paroxysmal cough with inspiratory whoop and post-tussive vomiting in an incompletely immunised infant is classic pertussis (whooping cough). Apnoeic episodes in young infants are a concerning complication. Diagnosis is confirmed by PCR of nasopharyngeal aspirate. Treatment is azithromycin. This infant has missed the 2-month and 4-month pertussis-containing vaccines.

Reference: Australian Immunisation Handbook – 2025 – Pertussis