title: Virulence Potential of Activatable Shiga Toxin 2d-Producing Escherichia coli Isolates from Fresh Produce.
abstract: Shiga toxin (Stx)-producing Escherichia coli (STEC) strains are food- and waterborne pathogens that are often transmitted via beef products or fresh produce. STEC strains cause both sporadic infections and outbreaks, which may result in hemorrhagic colitis and hemolytic uremic syndrome. STEC strains may elaborate Stx1, Stx2, and/or subtypes of those toxins. Epidemiological evidence indicates that STEC that produce subtypes Stx2a, Stx2c, and/or Stx2d are more often associated with serious illness. The Stx2d subtype becomes more toxic to Vero cells after incubation with intestinal mucus or elastase, a process named "activation." Stx2d is not generally found in the E. coli serotypes most commonly connected to STEC outbreaks. However, STEC strains that are stx2d positive can be isolated from foods, an occurrence that gives rise to the question of whether those food isolates are potential human pathogens. In this study, we examined 14 STEC strains from fresh produce that were stx2d positive and found that they all produced the mucus-activatable Stx2d and that a subset of the strains tested were virulent in streptomycin-treated mice.
authors.affiliation: Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA. angela.melton-celsa.ctr@usuhs.edu.
authors.forename: Angela R
authors.initials: AR
authors.lastname: Melton-Celsa
authors.affiliation: Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
authors.forename: Alison D
authors.initials: AD
authors.lastname: O'Brien
authors.affiliation: Division of Microbiology, U.S. Food and Drug Administration, College Park, Maryland 20740, USA.
authors.forename: Peter C H
authors.initials: PC
authors.lastname: Feng
mesh_terms: D000818:Animals; D002417:Cattle; D002522:Chlorocebus aethiops; D018556:Crops, Agricultural / Q000382:microbiology*; D004927:Escherichia coli Infections / Q000453:epidemiology; D029968:Escherichia coli Proteins; D006801:Humans; D008460:Meat / Q000382:microbiology; D051379:Mice; D022641:Shiga Toxin 2 / Q000096:biosynthesis; D022603:Shiga Toxins / Q000096:biosynthesis; D054323:Shiga-Toxigenic Escherichia coli / Q000302:isolation & purification* / Q000378:metabolism / Q000472:pathogenicity; D013307:Streptomycin / Q000008:administration & dosage; D014709:Vero Cells; D037521:Virulence Factors
chemical_list: D029968:Escherichia coli Proteins; D022641:Shiga Toxin 2; D022603:Shiga Toxins; D037521:Virulence Factors; D013307:Streptomycin