ARS | Publication request: PREVALENCE OF MULTI-DRUG RESISTANT SALMONELLA IN DAIRY CATTLE

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: June 12, 2006
Publication Date: September 9, 2006
Citation: Edrington, T.S., Callaway, T.R., Anderson, R.C., Nisbet, D.J. 2006. Prevalence of multi-drug resistant Salmonella in dairy cattle [abstract]. American Society for Microbiology. p. 52-53.

Technical Abstract: 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 that all utilized 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 (0 to 96% positive) 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. Even so, as the 24 month old heifers and mature cows were largely negative for MDR Salmonella, the use of a central calf/heifer facility does not appear to facilitate the spread of MDR Salmonella among dairy herds. Eleven different serogroups were identified with C1 being the predominant serogroup. The MDR Salmonella belonged to only one serogroup (B) and were predominantly of the serotypes Reading and Typhimurium. Twenty-eight different serotypes were identified with more types identified in the March collection (27), when overall Salmonella prevalence was substantially lower, compared to the October collection (17). The five most common serotypes in all classes of cattle in descending order of frequency were: Reading, Senftenberg, Montevideo, Fresno, and Cerro. No Salmonella Newport was identified. Only a small proportion of the cultured Salmonella isolates examined for antimicrobial resistance were MDR, although 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.