Mastitis Resistance to Enhance Dairy Food Safety

NON-TECHNICAL SUMMARY: Campylobacter in raw milk may pose a human health hazard. The purpose of this study is to develop detection methods for Campylobacter in raw milk, and educational materials on health hazards associated with Campylobacter.

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APPROACH: As part of objective 1, we will continue further studies on chronic E. coli infections and the associated immune response. This work includes characterization of the cytokine response of mammary cells and mammary tissue in vitro and in vivo after infection with coliform bacteria. As part of objective 2, we will characterize the molecular genetics and antimicrobial resistance of Klebsiella, using techinques such as multi-locus sequence typing, detection and sequence analysis of virulence genes, and genotypic and phenotypic detection of resistance to antimicrobials, specifically cephalosporins (extended-spectrum beta-lactamase resistance, ESBL). This includes characterization of populations of coliform bacteria from dairy cattle milk and feces, and from the dairy environment. As part of objective 3, we are developing a system to use bulk milk to monitor issues related to animal health, milk quality and food safety. A logistic framework for collection of samples and reporting of results is under development, and laboratory tests for foodborne pathogens are being developed. The focus of the Hatch-funded component of the Multistate project is development of PCR-based diagnostic assays for detection of zoonotic Campylobacter species in milk, and associated extension materials for dairy producers and consumers. Sensitivity of SYBR Green real-time PCR detection will be determined for C. jejuni and C. coli by testing of dilution series of ATCC control strains in nutrient broth and milk. Comparisons will be made between: (1) samples with or without overnight enrichment; (2) DNA-extraction using in-house methods or a commercial kit; (3) RT-PCR with and without internal amplification controls. <P>Published protocols for real-time PCR detection of Campylobacter in foods or feces serve as guidelines for testing protocols. After protocol optimization, bulk milk samples will be tested. Samples will be obtained through NY dairy cooperatives (30 samples/mo), and the National Animal Health Monitoring System. Results will be compared between fresh and frozen samples to determine whether samples can be stored frozen before shipping and testing. For 10 herds that test positive, daily samples will be collected and tested for 30 days, and bi-weekly samples for one year to assess day-to-day and seasonal fluctuations in shedding. The test will be offered to producers on a fee-for-service basis through Quality Milk Production Services (QMPS). A two-page document will be written explaining symptoms and transmission routes of campylobacteriosis, as well as measures to prevent disease. The document will also describe the value of testing, and the limitations of testing associated with fluctuating shedding levels. Documents will be hosted on the websites of the Milk Quality Improvement Program in the Department of Food Science (MQIP) and QMPS. Print-outs of the documents will be disseminated to producers that submit samples for testing for Campylobacter or other foodborne pathogens.