An official website of the United States government.
A three year longitudinal study of 130 dairy herds is proposed to: 1) identify the patterns of occurrence andshedding of Salmonella spp. and Campylobacter jejuni, and associated risk factors,on dairy farms in the Midwest and Northeast; 2) evaluate the relative sensitivity and specificity of different sampling frequencies for detection of Salmonella and C. jejuni in fecal and environmental samples; 3) determine susceptibility profiles of Salmonella and C. jejuni isolates to a number of antimicrobial agents; 4) compare conventional and organic dairy farms in the Midwest and Northeast with respect to: a) shedding, and b) susceptibility and resistance profiles of the two organisms to specific antimicrobial agents; and 5) determine molecular mechanisms involved in reduced susceptibility and/or development of resistance of Salmonella and C. jejuni isolates to antimicrobial agents.
Dairy farms will be selected from Michigan, Minnesota, New York, and Wisconsin. Fecal, water, milk, feed, and environmental samples will be collected and tested for the presence of specific strains of Salmonella and Campylobacter using standard molecular techniques. Further typing will be done by a modified Taqman procedure for Campylobacter, and phage molecular typing of Salmonella. In vitro susceptibility testing of the strains to a number of antimicrobial agents will be conducted. Risk factors associated with bacterial shedding and the development of resistance to selected antimicrobial agents will be evaluated using multi-variable statistical methods. Results from this study will provide ways to improve pre-harvest pathogen reduction by identifying factors related to shedding and antimicrobial resistance that can be changed by dairy producers.