EPIDEMIOLOGY, ECOLOGY, AND MOLECULAR GENETICS OF ANTIMICROBIAL RESISTANCE IN PATHOGENIC AND COMMENSAL BACTERIA FROM FOOD ANIMALS
Location: Bacterial Epidemiology and Antimicrobial Resistance
Title: Prevalence of Salmonella in beef and dairy cattle and potential pathogenicity of their isolates
Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: April 3, 2007
Publication Date: July 8, 2007
Citation: Jackson, C.R., Cray, P.J., Haro, J.H., Mcglinchey, B. 2007. Prevalence of Salmonella in beef and dairy cattle and potential pathogenicity of their isolates. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 56:138.
Salmonella is a leading cause of foodborne illness which can be spread to humans from a number of different sources. While all Salmonella serotypes have the potential to cause disease, certain serovars appear to be responsible for a variety of diseases in a diverse array of animal and human hosts. Salmonella Typhimurium, S. Enteritidis, and S. Newport are in the top five Salmonella serotypes implicated in human infections and S. Dublin is a common cause of cattle Salmonella infections. As a part of the animal arm of the National Antimicrobial Resistance Monitoring System (NARMS), prevalence, antimicrobial susceptibility and pulsed-field gel electrophoresis of Salmonella serotypes in beef and dairy cattle collected from 1997-2005 was examined. A total of 10,228 and 4,584 Salmonella from beef cattle and dairy cattle, respectively, were tested. Clinical status of isolates included slaughter (n=6813; 61.3%), diagnostic (n=3415; 30.7%) and on-farm (n=883; 8.0%) for beef cattle and diagnostic (n=3036; 66.2%) and on-farm (n=1548; 33.8%) for dairy cattle. For slaughter samples from beef cattle, the top three serotypes were S. Montevideo (13.9%), S. Anatum (8.9%), and S. Newport (7.6%). For diagnostic isolates, the top three serotypes from both beef and dairy cattle were the same, but ranked differently: S. Typhimurium var. 5- (15.8%), S. Newport (13.6%), and S. Typhimurium (13.1%) from beef cattle and S. Newport (24.3%), S. Typhimurium (19.7%), and S. Typhimurium var. 5- (18.6%) from dairy cattle. Regardless of source, 51.9% of all Salmonella from cattle were pan-susceptible in 2005. Through 2005, 45.4% of S. Typhimurium, 24.6% of S. Newport, and 13.4% of S. Typhimurium var. 5- from slaughter samples were pan-susceptible. Multidrug resistance (resistance to two or more antimicrobials) was 80.2% for S. Typhimurium var. 5-, 74.8% for S. Newport, and 52.0% for S. Typhimurium. Using PFGE, the most common pattern for all cattle isolates was for S. Newport (n=165). Results from this study demonstrate that differences in prevalence of Salmonella serotypes exist between beef and dairy cattle as well as clinical status of the animal.