Identification of Common Subpopulations of Non-Sorbitol-Fermenting, β-Glucuronidase-Negative Escherichia coli O157:H7 from Bovine Production Environments and Human Clinical Samples

Authors

Zhijie Yang, University of Nebraska - Lincoln
Joy Kovar, University of Nebraska -Follow
Jaehyoung Kim, University of Nebraska - LincolnFollow
Joseph Nietfeldt, University of Nebraska - LincolnFollow
David R. Smith, University of Nebraska - LincolnFollow
Rodney A. Moxley, University of Nebraska-LincolnFollow
Michael E. Olson, University of Nebraska Medical Center, Omaha, Nebraska
Paul D. Fey, University of Nebraska Medical Center
Andrew K. Benson, University of Nebraska - LincolnFollow

Document Type

Article

Date of this Version

11-1-2004

Comments

Published in APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Nov. 2004, p. 6846–6854. Copyright © 2004, American Society for Microbiology. Used by permission.

Abstract

Non-sorbitol-fermenting, β-glucuronidase-negative Escherichia coli O157:H7 strains are regarded as a clone complex, and populations from different geographical locations are believed to share a recent common ancestor. Despite their relatedness, high-resolution genotyping methods can detect significant genome variation among different populations. Phylogenetic analysis of high-resolution genotyping data from these strains has shown that subpopulations from geographically unlinked continents can be divided into two primary phylogenetic lineages, termed lineage I and lineage II, and limited studies of the distribution of these lineages suggest there could be differences in their propensity to cause disease in humans or to be transmitted to humans. Because the genotyping methods necessary to discriminate the two lineages are tedious and subjective, these methods are not particularly suited for studying the large sets of strains that are required to systematically evaluate the ecology and transmission characteristics of these lineages. To overcome this limitation, we have developed a lineage-specific polymorphism assay (LSPA) that can readily distinguish between the lineage I and lineage II subpopulations. In the studies reported here, we describe the development of a six-marker test (LSPA-6) and its validation in a side-by-side comparison with octamer-based genome scanning. Analysis of over 1,400 O157:H7 strains with the LSPA-6 demonstrated that five genotypes comprise over 91% of the strains, suggesting that these subpopulations may be widespread.