Octamer-based genome scanning distinguishes a unique subpopulation of Escherichia coli O157:H7 strains in cattle

Jaehyoung Kim, Joseph Nietfeldt, Andrew K. Benson

Research output: Contribution to journalArticlepeer-review

151 Scopus citations


Multilocus-genotyping methods have shown that Escherichia coli O157:H7 is a geographically disseminated clone. However, high-resolution methods such as pulse-field gel electrophoresis demonstrate significant genomic diversity among different isolates. To assess the genetic relationship of human and bovine isolates of E. coli O157:H7 in detail, we have developed an octamer- based genome-scanning methodology, which compares the distance between over- represented, strand-biased octamers that occur in the genome. Comparison of octamer-based genome-scanning products derived from >1 megabase of the genome demonstrated the existence of two distinct lineages of E. coli O157:H7 that are disseminated within the United States. Human and bovine isolates are nonrandomly distributed among the lineages, suggesting that one of these lineages may be less virulent for humans or may not be efficiently transmitted to humans from bovine sources. Restriction fragment length polymorphism analysis with lambdoid phage genomes indicates that phage- mediated events are associated with divergence of the lineages, thereby providing one explanation for the degree of diversity that is observed among E. coli O157:H7 by other molecular-fingerprinting methods.

Original languageEnglish (US)
Pages (from-to)13288-13293
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number23
StatePublished - Nov 9 1999
Externally publishedYes

ASJC Scopus subject areas

  • General


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