Affiliation:
1. Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow, Idaho 83844-3052
Abstract
ABSTRACT
Escherichia coli
O157:H7 causes hemorrhagic colitis and life-threatening complications. Because healthy cattle are reservoirs for the bacterium, ruminant infection models have applications in analyzing the relationship between cattle and this human pathogen and in testing interventions to reduce or prevent bovine colonization with this bacterium. Current approaches often do not reliably mimic natural, long-term bovine colonization with
E. coli
O157:H7 in older calves and adult animals (ages that enter our food chain). Based on the recent identification of the bovine rectoanal junction mucosa as a site of
E. coli
O157:H7 colonization, we developed a novel rectal swab administration colonization model. We compared this method with oral dosing and direct contact transmission (Trojan) methods.
E. coli
O157:H7 carriage status was determined by fecal or rectoanal mucosa swab culture. High (∼10
10
CFU) and low (∼10
7
CFU) oral doses of
E. coli
O157:H7 in sheep and cattle resulted in variable infection with the bacterium. Some animals became colonized with the bacteria and remained culture positive for several weeks, and some animals did not become colonized and rapidly cleared the bacteria in a few days. Pen mates of
E. coli
O157:H7 culture-positive Trojan cattle had a low infection rate and variable colonization status. However, rectal swab administration of
E. coli
O157:H7 to cattle resulted in consistent long-term colonization in all animals. The surprising ease with which long-term infections resulted from a single application of bacteria to the rectoanal mucosa also strongly supported this location as a site of
E. coli
O157:H7 colonization in cattle.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
43 articles.
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