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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #206457
Title: Comparison of the molecular genotypes of Escherichia coli O157:H7 from the hides of beef cattle in different regions of North America

Author
item Arthur, Terrance
item Bosilevac, Joseph - Mick
item Nou, Xiangwu
item Shackelford, Steven
item Wheeler, Tommy
item Koohmaraie, Mohammad

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2007
Publication Date: 7/20/2007
Citation: Arthur, T.M., Bosilevac, J.M., Nou, X., Shackelford, S.D., Wheeler, T.L., Koohmaraie, M. 2007. Comparison of the molecular genotypes of Escherichia coli O157:H7 from the hides of beef cattle in different regions of North America. Journal of Food Protection. 70(7):1622-1626.

Interpretive Summary: Cattle hides become contaminated with E. coli O157:H7 in the feedlot, during transport, and in the lairage environment at the processing facility and the bacteria are sometimes transferred inadvertantly to beef carcasses during processing. The experiment described herein was designed to identify the genetic diversity of E. coli O157:H7 isolates from beef cattle hides in nine major cattle-producing regions of North America. Hide prevalence for E. coli O157:H7 in the nine regions ranged from 9% to 85%. Analysis of DNA from 1193 E. coli O157:H7 isolates resulted in 277 unique types. Of the 277 unique types, 54 types contained isolates collected from multiple regions. After two subsequent rounds of analysis, there were still many isolates (n = 154) that could not be distinguished from others, even though they were collected from different regions separated by large geographical distances. On multiple occasions, strains isolated from cattle hides at processing plants in Canada were indistinguishable from cattle hide isolates collected in Kansas and Nebraska. This information shows the potential for indistinguishable strains to originate from multiple sources that can be separated by large distances and should be taken into account when source tracking isolates.

Technical Abstract: Cattle hides become contaminated with E. coli O157:H7 via pathogen transmission in the feedlot, during transport, and in the lairage environment at the processing facility and the bacteria can be transferred to beef carcasses during processing. Several studies have shown that E. coli O157:H7 strains possessing indistinguishable restriction digest patterns (RDP) can be isolated from distant locations. Most of these studies, however, examined RDP from strains isolated within a single region of the United States or Canada. The experiment described herein was designed to identify the molecular genotypes of E. coli O157:H7 isolates from beef cattle hides in nine major cattle-producing regions of North America. Prevalence for E. coli O157:H7 in sponge samples collected from beef cattle hides ranged from 9% to 85%. PFGE analysis of XbaI-digested genomic DNA from 1193 E. coli O157:H7 isolates resulted in 277 unique RDP. Of the 277 unique XbaI RDP, 54 RDP contained isolates collected from multiple regions. After two subsequent rounds of PFGE analysis (BlnI and SpeI), there were still many isolates (n = 154) that could not be distinguished from others, even though they were collected from different regions separated by large geographical distances. On multiple occasions, strains isolated from cattle hides in Canada had RDP that were indistinguishable after three enzyme digestions from cattle hide isolates collected in Kansas and Nebraska. This information clearly shows that strains with indistinguishable RDP originate from multiple sources that can be separated by large distances and should be taken into account when source tracking isolates based on PFGE.