Affiliation:
1. Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040
Abstract
ABSTRACT
Association of specific antimicrobial resistance patterns with unrelated selective traits has long been implicated in the maintenance of antimicrobial resistance in a population. Previously we demonstrated that
Escherichia coli
strains with a specific resistance pattern (resistant to
s
treptomycin,
su
lfadiazine, and
t
etracycline [SSuT]) have a selective advantage in dairy calf intestinal environments and in the presence of a milk supplement commonly fed to the calves. In the present study we identified the sequence of the genetic element that confers the SSuT phenotype and show that this element is present in a genetically diverse group of
E. coli
isolates, as assessed by macrorestriction digestion and pulsed-field gel electrophoresis. This element was also found in
E. coli
isolates from 18 different cattle farms in Washington State. Using in vitro competition experiments we further demonstrated that SSuT strains from 17 of 18 farms were able to outcompete pansusceptible strains. In a separate set of experiments, we were able to transfer the antimicrobial resistance phenotype by electroporation to a laboratory strain of
E. coli
(DH10B), making that new strain more competitive during in vitro competition with the parental DH10B strain. These data indicate that a relatively large genetic element conferring the SSuT phenotype is widely distributed in
E. coli
from cattle in Washington State. Furthermore, our results indicate that this element is responsible for maintenance of these traits owing to linkage to genetic traits that confer a selective advantage in the intestinal lumens of dairy calves.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
25 articles.
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