First Whole Genome Sequencing and Phylogenomic Characterization of a <em>Streptococcus halichoeri </em>Isolate from a Dog Case with Toxic Shock-like Syndrome in Romania

<jats:p>Streptococcus halichoery is an emerging, multi‑host pathogen with zoonotic potential that is frequently misidentified by routine diagnostics; whole‑genome sequencing (WGS) is essential to resolve its taxonomy, virulence repertoire, and antimicrobial resistance profile. In this paper we genomically characterized by whole‑genome sequencing an isolated Streptococcus halichoery from a clinical case of Toxic Shock-like Syndrome disease in an 11-year-old cross breed dog from Romania. This isolate (RO_Sh) produced a high‑quality 1.90 Mb draft genome across 57 contigs (N50 = 76,701 bp; GC = 41.70%). cgMLST analysis revealed a complete allelic profile, and phylogenetic comparison showed zero allelic distance between RO_Sh and Finnish mink, dog, raccoon, and seal isolates. SNP‑based phylogenetic analysis placed RO_Sh within a cluster of canine‑derived samples with short branch lengths and low SNP divergence, separating it from human, mink, fox, seal, consistent with a dog‑associated lineage and recent common ancestry among canine isolates. Resistance gene screening identified a strict PEDO‑1 subclass B3 metallo‑β‑lactamase (100% identity), confirming carbapenemase activity. The results support the classification of these bacteria as a zoonotic, potentially antimicrobial resistant bacteria. Continued genomic surveillance is essential to monitor and understand the emergence and dissemination of Streptococcus halichoeri in veterinary medicine.</jats:p>