S100A7 and mastitis: Types of pathogenic microorganisms are of equal importance, especially E. coli, which is mainly against invasion by S100A7 antibacterial activity [56,57], while it has low or no antibacterial activity for other pathogenic bacteria, such as Staphylococcus aureus [25]; yet the germline of E. coli doesn’t play a decisive role in the severity of its induced mastitis, differences in the main strains causing subclinical and clinical mastitis also lead to differences of S100A7 abundance, and the relationship between S100A7 abundance and the different strains remains unclear.