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Title: Salmonella on dairy operations in the United States: prevalence and antimicrobial drug susceptibility

Author
item BLAU, D - USDA,APHIS,CEAH
item MCCLUSKEY, B - USDA,APHIS,CEAH
item Ladely, Scott
item DARGATZ, D - USDA,APHIS,CEAH
item Cray, Paula
item FERRIS, K - USDA,APHIS,NVSL
item HEADRICK, M - FDA,CVM

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2005
Publication Date: 4/1/2005
Citation: Blau, D.M., Mccluskey, B.J., Ladely, S.R., Dargatz, D.A., Cray, P.J., Ferris, K.E., Headrick, M.L. 2005. Salmonella on dairy operations in the United States: prevalence and antimicrobial drug susceptibility. Journal of Food Protection. 68(4):696-702.

Interpretive Summary: Salmonella is a zoonotic pathogen which can be transferred from animals to humans, most often through consumption of contaminated food. Infection with Salmonella can cause mild to severe gastroenteritis in humans while infection in food animals is often with clinical signs of disease. As part of a national study of U.S. dairy operations conducted between March and September 2002, fecal samples were collected from representative cows in 97 dairy herds in 21 states and cultured to determine the prevalence of Salmonella shedding and to determine how susceptible these isolates were to a panel of 16 antimicrobial drugs. Salmonella species were recovered from the feces of at least one cow in 30.9% of the herds. Overall, 7.3% of fecal samples were culture positive for Salmonella. The three most frequently recovered serotypes were S. Meleagridis (24.1%), S. Montevideo (11.9%) and S. Typhimurium (9.9%). Approximately 83% of the Salmonella isolates recovered from dairy cows were susceptible to all antimicrobials tested. This study provides recent information on the prevalence and susceptibility patterns of Salmonella in dairy herds in addition to cow and herd characteristics and contributes to our understanding of the ecology of Salmonella in the dairy farm environment. These data are important to scientists, commodity groups, government regulators, and animal industry personnel as they study ways to reduce Salmonella in food animals as a means to reduce the incidence of human salmonellosis.

Technical Abstract: Salmonella species are important foodborne pathogens in humans that can be acquired through consumption of contaminated meat and dairy products. In addition, infection with Salmonella can be a significant animal health issue. As part of a national study of U.S. dairy operations conducted between March and September 2002, fecal samples were collected from representative cows in 97 dairy herds in 21 states and cultured to determine the prevalence of Salmonella shedding. Salmonella species were recovered from the feces of at least one cow in 30.9% of the herds. Overall, 7.3% of fecal samples were culture positive for Salmonella. The three most frequently recovered serotypes were Salmonella Meleagridis (24.1%), S. Montevideo (11.9%) and S. Typhimurium (9.9%). The susceptibilities of Salmonella isolates recovered were determined using a panel of 16 antimicrobial drugs. Salmonella isolates recovered from dairy cows showed relatively little resistance to these antimicrobial agents, with 83.0% being susceptible to all antimicrobials tested. This study provides recent information on the prevalence and susceptibility patterns of Salmonella in dairy herds in addition to cow and herd characteristics. These data contribute to understanding the ecology of Salmonella in the dairy farm environment.