A dominant clonal lineage of Streptococcus uberis in cattle in Germany

Abstract

Bovine mastitis causes enormous economic losses in the dairy industry with Streptococcus uberis as one of the most common bacterial pathogens causing clinical and subclinical variations. In most cases mastitis can be cured by intramammary administration of antimicrobial agents. However, the severity of the clinical manifestations can vary greatly from mild to severe symtoms. In this study, a comparative genomic analysis of 24 S. uberis isolates from three dairy farms in Germany, affected by different courses of infection was conducted. While there were sporadic mild infections in farm A and B, a large number of infections were observed within a very short period of time in farm C. The comparison of virulence genes, antimicrobial resistance genes and prophage regions revealed no features that might be responsible for this severe course. However, almost all isolates from farm C showed the same, novel MLST profile (ST1373), thus a clonal outbreak cannot be excluded, whereby the actual reason for the particular virulence remains unknown. This study demonstrates the importance of extensive metagenomic studies, including the host genomes and the environment, to gain further evidence on the pathogenicity of S. uberis.

A core genome multi-locus sequence typing scheme for Streptococcus uberis: an evolution in typing a genetically diverse pathogen

“…We further curated the core genome to exclude paralogous genes and genes with internal stop codons. Other studies have estimated the S. uberis core genome to contain between 1421 and 1567 genes [ 11 13 15 33 40 41 ] with disparities probably being due to the methodologies employed, parameters used and the number of isolates included. This was also evident in this study where the subset of newly sequenced isolates ( n =579) were determined to have a core genome size of 1531 genes when calculated by a alternative bioinformatics tool, Panaroo [ 32 ], which employs a different methodology to define the core genome.…”