Affiliation:
1. Department of Biology, SCA 110, University of South Florida, 4202 E. Fowler Avenue, Tampa, Florida
Abstract
ABSTRACT
Escherichia coli
is the most completely characterized prokaryotic model organism and one of the dominant indicator organisms for food and water quality testing, yet comparatively little is known about the structure of
E. coli
populations in their various hosts. The diversities of
E. coli
populations isolated from the feces of three host species (human, cow, and horse) were compared by two subtyping methods: ribotyping (using HindIII) and antibiotic resistance analysis (ARA). The sampling effort required to obtain a representative sample differed by host species, as
E. coli
diversity was consistently greatest in horses, followed by cattle, and was lowest in humans. The diversity of antibiotic resistance patterns isolated from individuals was consistently greater than the diversity of ribotypes.
E. coli
populations in individuals sampled monthly, over a 7- to 8-month period, were highly variable in terms of both ribotypes and ARA phenotypes. In contrast,
E. coli
populations in cattle and humans were stable over an 8-h period. Following the cessation of antibiotic therapy, the
E. coli
population in the feces of one human experienced a rapid and substantial shift, from a multiply antibiotic-resistant phenotype associated with a particular ribotype to a relatively antibiotic-susceptible phenotype associated with a different ribotype. The high genetic diversity of
E. coli
populations, differences in diversity among hosts, and temporal variability all indicate complex population dynamics that influence the usefulness of
E. coli
as a water quality indicator and its use in microbial source tracking studies.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
93 articles.
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