Whole genome sequencing for genomic characteristics, antimicrobial resistance mechanisms, virulence factors in Streptococcus agalactiae isolates recovered in China from cow.

Streptococcus agalactiae (S. agalactiae) is a pathogen that causes bovine mastitis, It causes a decline in milk production and quality, serious economic losses. Strains of serotypes Ia and II are the most commonly encountered in bovine mastitis in China. To date, some genome sequences of S. agalactiae from fish,human and bovine isolates have been reported. We aimed to investigate the virulence factors,antibiotic resistance profiles and genetic characteristics of serotypes Ia and II S. agalactiae strains SH33,XJMS02-12-1. For a further understanding of the genetic background of the pathogenicity of S. agalactiae, This study exploration the S. agalactiae isolates genomic characteristics (genome size, guanine-cytosine content, and Non-coding RNA) and phenotypic antimicrobial resistance (AMR), determined the occurrence of antimicrobial resistance genes and virulence factors. Whole genome sequencing revealed that the S. agalactiae comprising multiple antibiotic resistance and virulence genes. The results showed that S. agalactiae SH33,XJMS02-12-1 contains most of known virulence-associated factors, such as beta-H/C, CAMP factor, Fbs, HylB, sip, BibA, and C5a peptidase. CARD annotated 8 genes conferring resistance to tetracycline, aminoglycosides, erythromycin. In summary, we report here the antibiotic resistance profiles and virulence gene clustering of S. agalactiae isolates.