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Source and Prevalence of Multi-Drug Resistant Salmonella
in Dairy Cattle

Investigators
Edrington, Thomas
Institutions
USDA - Agricultural Research Service
Start date
2005
End date
2006
Objective
  1. Determine prevalence of multi-resistant Salmonella in dairy cattle (calves, heifers, lactating cattle, dry cows, and cull cows).
  2. Determine if co-mingling of calves from multiple farms at a heifer feedlot serves as a transmission vector for multi-resistant Salmonella back to the dairy.
  3. Examine waste milk for multi-resistant Salmonella prior to use as calf feed.
More information

Findings: To determine the prevalence of multi-drug resistant (MDR) Salmonella in dairy cattle and which groups of cattle may be more likely to harbor MDR Salmonella, we sampled animals on four commercial dairy farms and a central calf/heifer raising facility. Fecal samples were obtained from hutch calves, 12 and 24 month old heifers, lactating cows, dry cows, and cows in the sick/fresh pen in October 2005 and again in March 2006. Fecal Salmonella prevalence varied among groups of cattle and between the two collection periods. Hutch calves and cattle in the sick/fresh pen were more likely to harbor MDR Salmonella than heifers or lactating and dry cows. However, a significant number of MDR Salmonella were detected in lactating cattle on one farm during the October collection. The MDR Salmonella belonged to serogroup B and were predominantly of the serotypes Reading and Typhimurium. No Salmonella Newport was identified. A small portion of the isolates examined for antimicrobial resistance were MDR and 30 isolates were resistant to 9 or 10 antibiotics on the NARM's panel. While the presence of MDR Salmonella is a cause for concern, all isolates examined were susceptible to ciprofloxacin and ceftriaxone, two antibiotics used in the treatment of severe cases of human salmonellosis.

Funding Source
Nat'l. Cattlemen's Beef Assoc.
Project number
BC-2005-24
Categories
Antimicrobial Resistance
Bacterial Pathogens