Rapid progression from croup to complete lung collapse: a case report of central airway obstruction by mucopurulent cast in influenza A (H3N2) and Pseudomonas aeruginosa coinfection in a toddler

Croup is a common presentation in pediatric emergency settings, most often caused by viral infections. However, when influenza A virus co-occurs with Pseudomonas aeruginosa infection, it can lead to rare and lethal complications. We report a case of a 13-month-old boy who presented with fever and croup. The patient developed suffocation after 4.5 h of hoarseness and respiratory distress, with poor response to glucocorticoids therapy. Despite mechanical ventilation, respiratory failure persisted. Serial chest radiographs over a 7-h period revealed rapid progression to complete left lung atelectasis. Bronchoscopy identified complete obstruction of the left main bronchus by a purulent mucus plug, which was removed resulting in lung re-expansion. Etiological analysis confirmed co-infection with influenza A virus (H3N2) and Pseudomonas aeruginosa . The patient was treated with sensitive antibiotics and peramivir, and was discharged on day 9 with no recurrence of symptoms.