Virulence, genomic features, and antimicrobial resistance of a highly virulent Streptococcus iniae ST4 from…

StudyMicrobial pathogenesis· Jun 2026

Virulence, genomic features, and antimicrobial resistance of a highly virulent Streptococcus iniae ST4 from diseased yellow catfish.

Tianlong Lan, Lingyun Lin, Tonglei Wu … Xiaoyi Pan

Medical MicrobiologyStudyQ2IF 4.4

Streptococcus iniae ST4 strain killed catfish at very low bacterial doses.

Virulence, genomic features, and antimicrobial resistance of a highly virulent Streptococcus iniae ST4 from diseased yellow catfish.

Tianlong Lan … Xiaoyi Pan

Microbial pathogenesis · Jun 2026

Background

Streptococcosis is an emerging bacterial disease in freshwater aquaculture that poses a substantial threat to animal health and production sustainability.

Methods

Multilocus sequence typing (multilocus sequence typing) assigned the isolate to sequence type 4 (ST4).

2.48 × 10^3 CFU/mL

Results

2.48 × 10^3 CFU/mL

Median lethal dose; a lower value means the strain is more virulent.

More results

A dominant bacterial strain, designated as HSY24518-1S, was identified as Streptococcus iniae, physiological, and biochemical characteristics, as well as lctO and 16S rRNA gene sequence analyses.

More results

Whole-genome sequencing revealed a draft genome of 2.05 Mb (GenBank accession JBVLZU000000000), containing 219 putative virulence-related genes and 161 antimicrobial resistance-associated genes.

PCR assays confirmed the presence of seven key virulence genes (simA, scpI, pgm, cpsD, pdi, sagA, and cfi).

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Conclusion · 1 of 2

These findings provide detailed insights into the genomic characteristics, virulence potential, and antimicrobial resistance profile of a highly virulent S.

Conclusion · 2 of 2

iniae strain, thereby supporting improved diagnosis, treatment, and control of streptococcosis in cultured fish.