A49-27 Pseudomonas Aeruginosa Pneumonia With Pulmonary Cavitation in a Critically Ill Patient - Case Report

Abstract Introduction Pulmonary cavitation is a severe manifestation of pneumonia, typically associated with virulent pathogens such as Staphylococcus aureus. Although uncommon, Pseudomonas aeruginosa can cause necrotizing pneumonia with abscess formation, especially in critically ill or immunocompromised patients. The presence of cavities implies pulmonary necrosis and entails diagnostic and therapeutic challenges in the intensive care unit (ICU). Case Presentation A 61-year-old woman with a history of Chronic Obstructive Pulmonary Disease (COPD), morbid obesity, and prior venous thromboses. She was admitted to the ICU for viral pneumonia (Influenza A and Parainfluenza 1) that progressed to severe Acute Respiratory Distress Syndrome (ARDS) and septic shock. She required prolonged mechanical ventilation, repeated prone positioning, and a tracheostomy. Despite advanced supportive care, fever and respiratory deterioration persisted, suggesting bacterial superinfection. Microbiological isolation confirmed P. aeruginosa. Broad-spectrum antibiotic therapy was initiated. The clinical course was protracted, with episodes of hemoptysis and intermittent need for vasopressor and inotropic support; nevertheless, she progressed to clinical stabilization. A cavitary lesion persists in the lateral and posterior basal segments of the right lower lobe, measuring ≈39 × 50 mm (previously 51 × 67 mm), with adjacent subsegmental consolidation in the posterior aspect of the same lobe, showing appropriate contrast enhancement and no signs of parenchymal necrosis; associated bibasilar fibro-atelectatic bands and a free right pleural effusion (anteroposterior diameter up to 25 mm). Figures 1 show this same cavitation and the adjacent consolidation. Discussion Cavitation due to P. aeruginosa is rare, even in critically ill patients. In post-influenza settings, Staphylococcus aureus is usually suspected; however, in this patient, risk factors for Gram-negative bacilli coexisted (COPD, mechanical ventilation, prolonged ICU stay), broadening the differential diagnosis. This case underscores the need to consider Pseudomonas when a pulmonary cavity appears during post-viral ARDS and to escalate/target antibiotics according to microbiology. Conclusion This case demonstrates that in post-influenza ARDS, pulmonary cavitation can be caused by P. aeruginosa. It is essential to consider unusual pathogens and provide comprehensive management to optimize prognosis. This abstract is funded by: None