Genomic analysis of the Streptococcus anginosus group; taxonomic implications, evolutionary insights and clinical considerations

Long-read genomic analysis of 25 patients’ invasive Streptococcus anginosus group isolates shows GTDB-Tk and MALDI-TOF agree only 42.8%, revealing four S. anginosus taxa.

• Why it matters: Misclassification limits accurate diagnosis and obscures prognostic markers for severe invasive disease, despite the group’s potential life-threatening impact in otherwise healthy people.
• What they did: Closed genomes from 29 isolates (25 hospitalized) and 21 controls were classified with GTDB-Tk plus 211 references, then analyzed with recombination-aware phylogenies, mobilome and CAZyme/gapseq profiling, and lineage-adjusted genome-wide association testing.
• The result: Carbohydrate utilisation and invasive propensity are lineage-associated, and a ~15Kbp glycosaminoglycan utilisation locus in the highest-severity taxa predicts direct host glycosaminoglycan feeding, while no single gene or SNP explains invasiveness after lineage adjustment.

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