Case Report: Sequential mNGS captures fatal HSV-1 reactivation after intestinal obstruction-associated ARDS in a 91-year-old.

Herpes simplex virus type 1 (HSV-1) is a ubiquitous pathogen. Nevertheless, disseminated HSV-1 infection with confirmed viremia and fatal acute respiratory distress syndrome (ARDS) following intestinal obstruction in very old individuals is exceedingly rare. Here we report a 91-year-old patient with previously intact immunity who developed ARDS after incomplete intestinal obstruction, followed by HSV-1 reactivation. Although routine microbiological tests remained negative, five consecutive metagenomic next-generation sequencing (mNGS) assays dynamically tracked the evolving pathogens throughout the disease course. Despite broad-spectrum antibiotics, antifungals, antivirals, corticosteroids, IVIG, and mechanical ventilation, the patient's refractory hypoxemia remained uncorrected, leading to multiple organ dysfunction and death. This case highlights a rare clinical scenario and provides valuable insights for the diagnosis and management of critically ill elderly patients, offering a comprehensive, longitudinal perspective on the clinical application of mNGS.