Genotypic characterization of Streptococcus didelphis causative of fatal infection in white-eared opossums.

This article presents the first comprehensive whole-genome characterization of clinical *Streptococcus didelphis* strains isolated from white-eared opossums (*Didelphis albiventris*), a pathogen previously linked to severe infections in opossums. Using long-read sequencing via the MinION platform, the study identified genomic features including streptolysin biosynthesis clusters, a conserved genomic island with regulatory and transport genes, antimicrobial resistance (AMR) genes across multiple drug classes, and 33 predicted virulence factors, although phenotypic resistance was not observed. Phylogenetic analyses showed high similarity between clinical and reference strains without evidence of clonality, and four housekeeping genes (dnaN, gki, pros, and xpt) were proposed for sequence typing of *S. didelphis*. These findings provide foundational genomic insights into the pathogenicity of *S. didelphis* and highlight the need for further research on its clinical impact and potential zoonotic transmission.