Case Report: Necrotizing fasciitis caused by Vibrio vulnificus without recalled seafood or seawater exposure diagnosed by metagenomic next-generation sequencing.

Vibrio vulnificus is a highly virulent marine Gram-negative pathogen that rapidly induces soft tissue necrosis and fatal septic shock, with infections generally linked to raw seafood ingestion or open wound contact with seawater. We report an atypical severe case of V. vulnificus septic shock in a 60-year-old male patient without recalled seafood or seawater exposure and without classic underlying high-risk diseases such as liver cirrhosis and diabetes mellitus. The patient presented with rapidly progressive swelling and subcutaneous ecchymosis of the right lower limb, which quickly deteriorated into refractory septic shock within 24 h. Conventional empiric broad-spectrum antibiotics failed to halt disease progression before pathogen identification. Metagenomic next-generation sequencing (mNGS) rapidly detected V. vulnificus sequences on the second admission day, and the diagnosis was further confirmed by blood culture. Multidisciplinary interventions including repeated radical surgical debridement, vacuum sealing drainage (VSD), targeted anti-infective therapy and comprehensive organ support finally achieved complete recovery. The patient recovered normal walking function during six-month outpatient follow-up. This rare occult infection case reminds clinicians to maintain high suspicion of V. vulnificus infection for rapidly advancing necrotizing fasciitis combined with septic shock, even when no aquatic exposure is recalled. Meanwhile, this work validates the critical value of mNGS for early pathogen identification in unexplained life-threatening sepsis.