PARTNERSHIP: DEFINING AND MANAGING STAPHYLOCOCCUS CHROMOGENES INTRAMAMMARY INFECTIONS IN PRIMIPAROUS DAIRY COWS

Our long-term goal is to improve the udder health status and productivity of dairy heifers. The main objective of the proposed research is to characterize S. chromogenes isolates that, based on phenotype, appear to be either associated with chronic high SCC IMIs, chronic low SCC IMIs, or simply colonize the teat skin using molecular methods. These data will then be used to determine if the phenotypic behavior is reproducible and if certain strains can be used to favorably alter mammary flora in the heifer by providing protection from a major mastitis pathogen, Staphylococcus aureus. We hypothesize that strain specific differences can be determined and that certain strains will produce repeatable phenotypic outcomes when used in an in vivo challenge model in heifers. Our preliminary data offer evidence of clear differences among isolates with regard to IMI outcomes and provide a repository of strains necessary to complete the proposed objectives. The research team assembled is uniquely positioned for the proposed research, as they combine expertise in bovine mammary health, bacterial molecular characterization, and mammary gland challenge models.Specific objectives of this project include to following:Determine predictable molecular patterns of S. chromogens isolates deemed to be chronic high somatic cell count associated, chronic low somatic cell count associated, or teat skin associated by comparing phenotypic behavior to bacterial whole genome sequences, MLST strain types, and MALDI-TOF fingerprintsDetermine when S. chromogenes IMIs occur in the heifer to better focus implementation of preventive management strategies.Determine if phenotypic behaviors of S. chromogenes IMIs are reproducible using in vivo challenge models.