A 25-day-old term infant born at home presents with repetitive staccato cough and tachypnoea for one week. The child is afebrile and feeding adequately. Chest X-ray shows diffuse interstitial infiltrates. Total leukocyte count is normal with 15 percent eosinophils. The most likely causative agent is:

• A Chlamydia trachomatis ✓
• B Bordetella pertussis
• C Respiratory syncytial virus
• D Cytomegalovirus

Explanation

Chlamydial pneumonia of infancy occurs between 2 weeks and 3 months of age, acquired during passage through an infected birth canal. The classic constellation is an afebrile staccato cough, diffuse interstitial infiltrates, and peripheral eosinophilia. Pertussis in young infants also causes paroxysmal cough but is marked by marked lymphocytosis rather than eosinophilia, and RSV bronchiolitis typically features wheeze and fever. Treatment is oral erythromycin or azithromycin.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.