Identification and pathogenicity analysis of Streptococcus equinus FMD1, a beta-hemolytic strain isolated from forest musk deer lung

Streptococcus spp. cause a wide range of diseases in animals and humans. A Streptococcus strain (FMD1) was isolated from forest musk deer lung. To identify the bacterium at the species level and investigate its pathogenicity, whole genome sequencing and experimental infections of mice were performed. The genome had 97.63% average nucleotide identity with the S. equinus strain. Through virulence gene analysis, a beta-hemolysin/cytolysin genome island was found in the FMD1 genome, which contained 12 beta-hemolysin/cytolysin-related genes. Hemolytic reaction and histopathological analysis established the strain’s pathogenicity in mice. This is the first report of a beta-hemolytic S. equinus strain in forest musk deer identified based on phenotypic and genotypic analyzes; this strategy could be useful for analyzing pathogens affecting rare animals.