Amy F Helgerson

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Edema disease is a systemic disease of weaned pigs caused by host-adapted strains of Escherichia coli, most commonly belonging to serogroup O138, O139, or O141. In the late 1990s, E. coli O147 strains containing the virulence genes f18, sta, stb, and stx(2) were recovered from outbreaks of edema disease in the United States. Pulsed-field gel electrophoresis(More)
Escherichia coli O157:H7 is only occasionally isolated from healthy swine, but some experimentally infected animals will shed the organism in their feces for at least 2 months. Potential explanations for the paucity of naturally occurring infections in swine, as compared to cattle, include a lack of animal-to-animal transmission so that the organism cannot(More)
We assessed the ability of a kanamycin-marked Stx phage to move into a commensal, ovine Escherichia coli strain in the ruminant gastrointestinal tract. Transduction was detected in 19/24 sheep tested, resulting in the recovery of 47 transductants. Subtherapeutic doses of the quinolone antibiotic enrofloxacin did not increase the rate of transduction.
Isogenic strains of Escherichia coli O157:H7, missing either stx(2) or the entire Stx2-encoding phage, were compared with the parent strain for their abilities to colonize sheep. The absence of the phage or of the Shiga toxin did not significantly impact the magnitude or duration of shedding of E. coli O157:H7.
Hemolytic uremic syndrome (HUS) is a systemic and potentially fatal complication of gastroenteritis secondary to Shiga toxin-producing enterohemorrhagic Escherichia coli (EHEC) infection characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal damage. Shiga toxin (Stx), the toxin principle in HUS, is produced locally within the(More)
Outbreaks of Escherichia coli O157:H7 in the United States due to contaminated foods are a public health issue and a continuing problem. The major reservoir for these organisms is the gastrointestinal tract of ruminants where they are a member of the resident microbiota. Several factors that contribute to the colonization of cattle have been identified, but(More)
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