Septic Shock Caused by Coinfection of Shewanella algae Bloodstream Infection and Epstein-Barr Virus: Clinical Characteristics and Genomic Analysis.

Shewanella algae, a marine-origin opportunistic pathogen, has shown a significant increase in non-coastal infections, yet its environmental adaptability and synergistic pathogenic mechanisms with Epstein-Barr virus (EBV) coinfection remain unclear. This study reports a clinical case of S. algae bloodstream infection complicated by EBV reactivation leading to septic shock in Sichuan Province, China, and elucidates the molecular mechanisms through genomic analysis. Pathogen identification was performed via blood culture, antibiotic susceptibility testing, and genomic annotation. The strain harbored resistance genes (acrB, tolC, tet(35), golS) and virulence factors (bplL/bplF, clpC/clpP, tonB). Phylogenetic analysis indicated the highest genetic affinity to freshwater-derived Shewanella chilikensis, while pan-genome analysis identified 1412 unique genes, including transmembrane transporters and carbohydrate-active enzyme genes, suggesting freshwater adaptive evolution. Metagenomic next-generation sequencing (mNGS) detected a high EBV load. The patient succumbed to multi-organ failure. This study reveals that S. algae may evolve freshwater adaptability to cause inland infections, and EBV coinfection accelerates septic shock through immunosuppression and inflammatory cascades. Genomic analysis provides critical insights for precision diagnosis and treatment of polymicrobial infections.