Date of Award
9-4-2015
Document Type
Thesis
Degree Name
Agriculture, MSA
First Advisor
Donald Kennedy
Committee Members
David Gilmore; Seo-eun Choi
Call Number
LD 251 .A566t 2015 B56
Abstract
Sixty-five million U.S. citizens become ill from foodborne bacteria annually; 73,000 of these bacterial illnesses are caused by Shiga-toxin producing Escherichia coli (STEC) O157. Cattle are a reservoir of STEC; therefore, STEC contamination of beef is a significant food safety concern in the U.S. On-farm STEC control measures may reduce the incidence of contamination in processing facilities. The objective of this study was to determine prevalence of O157 and non-O157 STEC on beef cattle farms in eastern Arkansas, and to possibly identify farm management and/or environmental risk factors associated with STEC prevalence in cattle. Rectal swab samples (10 cows per farm) were collected on 16 farms during July – Sept. 2013 (average daily temp. = 24.2 °C) and 18 farms during Sept.-Nov. 2012 (average daily temp. = 16.4 °C). In this study, the prevalence of STEC on cattle farms was determined using cultural methods and agglutination tests. Triplicate samples (rectal swabs, soil, and water) were collected from each farm. Following enrichment, samples were streaked onto selective and differential media. Colonies were chosen based on characteristic appearance, confirmed as E. coli by positive indole and negative citrate tests, and confirmed as O157 or as other STEC using latex agglutination tests. Every farm had at least one animal that tested positive for non-O157. The proportion of cattle testing positive for O157 at each farm ranged from 0 to 100%. Prevalence for O157 was increased (p< 0.05) for warm season vs. cool season (62% vs. 18%). There was no seasonal difference (p = 0.0649) observed in the mean of proportions of rectal samples that tested positive for non-O157. Some form of STEC was detected in environmental samples (soil or water) on 94% of the farms. These data indicate that the prevalence of STEC is widespread in beef cattle herds located in eastern Arkansas, and STEC O157 prevalence was different in cattle sampled during the summer as compared with those sampled in the fall.
Rights Management
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Breckenridge, Tiffani Elizabeth, "Seasonal Prevalence of Shiga-Toxin Producing Escherichia Coli on Beef Cattle Farms in Eastern Arkansas" (2015). Student Theses and Dissertations. 722.
https://arch.astate.edu/all-etd/722
