S. M. L. Stevenson

Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada

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Publications (3)4.84 Total impact

  • S. R. Cook · S. J. Bach · S. M. L. Stevenson · R. DeVinney · AA Frohlich · L. Fang · T. A. McAllister
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    ABSTRACT: Spray-dried whole egg prepared from eggs laid by non-immunized hens (EG) or hens immunized with the C-terminal domain of Escherichia coli O157:H7 intimin (EG-IgY) was fed to experimentally inoculated sheep, to investigate the efficacy of orally administered polyclonal anti-E. coli O157:H7 antibodies (IgY) for reducing the duration and level of fecal shedding of E. coli O157:H7 by ruminants. Thirty Canadian Arcott ram lambs were orally inoculated on day 0 with 1010 colony-forming units (CFU) of a three-strain mixture of nalidixic acid-resistant E. coli O157:H7. On each of days 2, 3 and 4, the rams (n = 6) were fed 100 g of EG and/or EG-IgY in proportions of 100:0 (CON), 0:100 (HIGH), 50:50 (MED), or 75:25 (LOW). A fifth treatment (denoted variable, VAR) comprised feeding HIGH, MED and LOW on days 2, 3, and 4, respectively. Fecal samples collected on 19 occasions over 85 d (4x in the first wk; 2x/wk for 3 wk; and 1x/wk for 9 wk) were assessed for E. coli O157:H7 by direct plating or enrichment and immunomagnetic separation. Throughout the 85 d, numbers of E. coli O157:H7 shed by the rams were lower (P < 0.001) in HIGH and MED than in CON, and the duration of shedding was shorter (P < 0.005) in HIGH than in CON. Fewer (P < 0.005) samples were culture-positive in HIGH than in CON. Oral dosing of specific IgY has potential to decrease the duration and level of fecal shedding of E. coli O157:H7 by ruminants.
    No preview · Article · Sep 2005 · The Canadian veterinary journal. La revue veterinaire canadienne
  • S M L Stevenson · S R Cook · S J Bach · T A McAllister
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    ABSTRACT: To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 10(4) CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P < 0.001) their ORP values to < 700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 10(4) CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24 degrees C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P < 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to < or = 848 mV. When stored in the dark, the diluted EO waters retained an ORP of > 848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4 degrees C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.
    No preview · Article · Aug 2004 · Journal of food protection
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    ABSTRACT: To determine the incidence of transfer of a naturally occurring rifampicin-resistant strain of Escherichia coli (RREC) among cattle in a research feedlot. During three separate experiments, steers in three different pens were orally inoculated with RREC originally isolated from bovine faeces. Faecal swabs were performed on all steers in the feedlot at approximately 5 week intervals thereafter. Faecal grab samples were collected from steers in the inoculated and the immediately adjacent pens for up to 4 months. In all three experiments, the inoculated steers and penmates shed RREC within 48 h, and then shed intermittently throughout the sampling periods. Transfer of RREC to steers in an adjacent pen was confirmed only during the first experiment, but never to those in non-adjacent pens. All recovered RREC isolates were compared with the inoculated strain using multiple methods indicating that all RREC isolates were descendants of the original inoculated strain. Detection of the RREC strain on the pen floor and within the animal handling system, but not in the feed troughs or water bowls, suggests faecal-oral to be the primary mode of transmission among animals. The results suggest that in the absence of selective pressure, antibiotic-resistant bacteria may persist in cattle for a short duration but widespread transfer among cattle in a feedlot environment may be an exception rather than the norm. Modifications to feedlot management are discussed.
    Full-text · Article · Feb 2003 · Journal of Applied Microbiology

Publication Stats

43 Citations
4.84 Total Impact Points

Institutions

  • 2004
    • Agriculture and Agri-Food Canada
      • Dairy and Swine Research and Development Centre (DSRDC)
      Ottawa, Ontario, Canada
  • 2003
    • University of Lethbridge
      • Department of Biological Sciences
      Lethbridge, Alberta, Canada