A Case of Lung Abscess Caused by <i>Pseudomonas aeruginosa</i> after a Near-drowning Episode

Background Aspiration pneumonia is one of the most severe complications associated with near-drowning and is referred to as drowning-associated pneumonia (DAP). Inhaled water may be contaminated by various pathogens, thereby facilitating DAP development. The causative organisms of DAP differ from those of community-acquired pneumonia, with Gram-negative bacilli being predominant. Case presentation We herein report an 83-year-old Japanese man with chronic kidney disease who presented to the emergency department after a near-drowning episode. His oxygen saturation level was 86% despite receiving oxygen via a 10 L/min reservoir mask. He was admitted to the intensive-care unit, where high-flow nasal cannula therapy (50 L/min with an FiO₂ of 1.0) was initiated. His respiratory condition gradually improved, and he was transferred to the general ward. However, on day 10 of hospitalization, the patient developed a fever. Chest computed tomography (CT) revealed a new cavity in the right upper lobe, which was suggestive of a lung abscess. Ceftriaxone was initiated but was ineffective. Sputum culture on day 10 revealed Pseudomonas aeruginosa, and cefepime was subsequently administered. His fever resolved, and follow-up CT on day 23 showed marked improvement in the cavity and surrounding consolidation. Due to suspected cefepime-induced acute kidney injury, the antibiotics were switched to moxifloxacin, and the patient was discharged on hospital day 28. Conclusion Following macroaspiration events, clinicians should evaluate the risk of pneumonia and likely pathogens. In patients who develop pneumonia after near-drowning, empirical coverage of Gram-negative organisms, including P. aeruginosa, should be considered.