Bactericidal killing and phagocytosis by milk phagocytes of distinct bovine-associated staphylococci species and strains in primiparous and multiparous dairy cows

Abstract

Mastitis affects not just the profitability of the farm but also is associated with animal welfare concerns, public health risk due to antimicrobial residues and emergence of bacterial resistance. Striving for a complete elimination of antimicrobial use in dairy cattle is unrealistic though a reduction is recommended and feasible. From that point of view, innovative tools enabling an increase in the natural ability of animals to resist infection could be of great value. The greatest obstacle in establishing this kind of strategies is a lack of understanding of many aspects of the interaction among mastitis-pathogens species and strains and the host. Phagocytes, such as neutrophils and macrophages, are essential for innate host defense against invading microorganisms and eliminate pathogens. Staphylococcal species represent an important cause of bovine mastitis, and there is a gap in our knowledge on the their epidemiology, virulence and interaction with host. The genus is usually divided into the coagulase-positive staphylococci with S. aureus remaining the most significant mastitis pathogen among the staphylococci and the heterogeneous group of coagulase-negative staphylococci which have become the most commonly isolated bacterial pathogens from milk samples of dairy cows and heifers in many regions and countries. Thus, the proposed project aimed at explore the difference in the ability of bovine-associated staphylococcal species and strains to resist phagocytosis and bactericidal killing by bovine phagocytes. Here, the milk phagocyte function (neutrophil phagocytosis, macrophage phagocytosis and the phagocyte bactericidal killing) in primiparous and multiparous cows will also be investigated. (AU)