Pulmonary Infiltrates, Airway Mucosal Lesions and Respiratory Microbiology After Freshwater Drowning: A Case Report

Early pulmonary abnormalities after freshwater drowning can be overinterpreted as bacterial pneumonia, especially when inflammatory biomarkers and respiratory microbiology are positive. A 20-year-old man was resuscitated after approximately 2 min of freshwater submersion. Day 1 chest CT showed bilateral lower-lobe-predominant opacities compatible with non-cardiogenic pulmonary oedema and aspiration-related lung injury, with near-complete resolution by Day 25. Day 3 bronchoscopy showed diffuse, non-removable, millet-seed-like whitish tracheal mucosal protrusions with hyperaemia and oedema, compatible with acute irritative airway injury. BALF mNGS detected multiple gram-negative bacterial signals, predominantly Klebsiella pneumoniae, while sputum culture yielded ESBL-negative, susceptible K. pneumoniae. Possible drowning-associated pneumonia was considered because of aspiration, fever, markedly elevated inflammatory biomarkers and concordant microbiology; however, rapid radiological improvement and clinical stability suggested a substantial non-infectious component. The patient recovered after an 8-day course of piperacillin-tazobactam without antibiotic escalation, corticosteroids, mechanical ventilation or acute respiratory distress syndrome.