Genomic content typifying a prevalent clade of bovine mastitis-associated Escherichia coli

Abstract

AbstractE. colirepresents a heterogeneous population with capabilities to cause disease in several anatomical sites. Among sites that can be colonised is the bovine mammary gland (udder) and a distinct class of mammary pathogenicE. coli(MPEC) has been proposed. MPEC are the principle causative agents of bovine mastitis in well-managed dairy farms, costing producers in the European Union an estimated €2 billion per year. Despite the economic impact, and the threat this disease presents to small and medium sized dairy farmers, the factors which mediate the ability forE. colito thrive in bovine mammary tissue remain poorly elucidated. Strains belonging toE. coliphylogroup A are most frequently isolated from mastitis. In this paper, we apply a population level genomic analysis to this group ofE. colito uncover genomic signatures of mammary infectivity. Through a robust statistical analysis, we show that not all strains ofE. coliare equally likely to cause mastitis, and those that do possess specific gene content that may promote their adaptation and survival in the bovine udder. Through a pan-genomic analysis, we identify just three genetic loci which are ubiquitous in MPEC, but appear dispensable forE. colifrom other niches.