Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to mastitis, a disease causing great economic losses in dairy production worldwide. E. coli often causes acute mastitis in cows, with particular strains causing chronic mastitis due to persistent IMI. Mammary pathogenic E. coli (MPEC) may be a novel E. coli pathotype, which is it yet to be fully characterized. Specifically, MPEC virulence factors (VFs) involved in mastitis pathogenesis were not entirely described. The objective of this study was to characterize MPEC through whole genome and phenome comparative analysis. Whole genome sequences and predicted proteomes showed a high degree of similarity between MPEC, and significant differences from non-MPEC and other E. coli pathotypes were found. VFs identified in MPEC were associated with lipopolysaccharide synthesis, iron acquisition systems and sugars metabolism. Unique VFs associated with MPEC causing either acute mastitis, such as cytotoxic factors, or chronic mastitis, such as biofilm and intra-cellular survival factors, were also identified, suggesting the existence of sub-pathotypes of MPEC. Phenome analysis revealed few reactions unique to MPEC, with MPEC causing persistent IMI being the most versatile in terms of nutrients metabolized, and MPEC causing acute mastitis the least. This is the first characterization of MPEC using whole genome sequence and phenome analysis.
