Case Report: VV-ECMO rescue of severe pneumonia with polymicrobial mNGS detections and uncertain EBV significance in obesity

) who was admitted with rapidly progressive pneumonia, sepsis, acute hypoxemic respiratory failure, and multiorgan dysfunction [Sequential Organ Failure Assessment (SOFA) score, 9]. Despite invasive ventilation, one approximately 28-h prone-positioning session, and broad-spectrum antimicrobials, oxygenation deteriorated; immediately before extracorporeal support, PaO₂ was 52 mmHg on FiO₂ 1.0 (PaO₂/FiO₂, 52 mmHg). The course included blood-tinged secretions, suspected alveolar hemorrhage without a documented progressively bloody serial lavage pattern, and complete left lung atelectasis. Bronchoalveolar lavage fluid metagenomic next-generation sequencing (mNGS) detected Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Legionella pneumophila, and a high Epstein-Barr virus (EBV) sequence burden. Admission blood cultures and conventional sputum culture showed no bacterial growth. On hospital day 3, venovenous extracorporeal membrane oxygenation (VV-ECMO) was initiated at 3,510 rpm, with blood flow 5.0 L/min and sweep gas flow 4.5 L/min. Adjunctive intravenous acyclovir (0.75 g every 8 h for 7 days) was administered because of the high EBV burden, although its clinical benefit in EBV pulmonary disease is unproven. VV-ECMO was discontinued on hospital day 18, extubation occurred on hospital day 24, and the patient subsequently returned to normal daily life. The clinical value of this case lies in management of a compound, potentially reversible phenotype rather than proof of any single microbial cause: severe pneumonia with polymicrobial mNGS detections, high EBV burden of uncertain significance, suspected hemorrhagic lung injury, unilateral atelectasis, and obesity-related respiratory mechanics successfully bridged with VV-ECMO.