Identification of intermediate in evolutionary model of enterohemorrhagic Escherichia coli O157

Emerg Infect Dis. 2012 Apr;18(4):582-8. doi: 10.3201/eid1804.111414.

Abstract

Highly pathogenic enterohemorrhagic Escherichia coli (EHEC) O157 cause a spectrum of clinical signs that include diarrhea, bloody diarrhea, and hemolytic uremic syndrome. The current evolutionary model of EHEC O157:H7/H(-) consists of a stepwise evolution scenario proceeding from O55:H7 to a node (hypothetical intermediate) that then branches into sorbitol-fermenting (SF) O157:H(-) and non-SF (NSF) O157:H7. To identify this hypothetical intermediate, we performed single nucleotide polymorphism analysis by sequencing of 92 randomly distributed backbone genomic regions of 40 O157:H7/H(-) isolates. Overall, 111 single nucleotide polymorphisms were identified in 75/92 partial open reading frames after sequencing 51,041 nt/strain. The EHEC O157:H7 strain LSU-61 from deer occupied an intermediate position between O55:H7 and both O157 branches (SF and NSF O157), complementing the stepwise evolutionary model of EHEC O157:H7/H(-). The animal origin of this intermediate emphasizes the value of nonhuman reservoirs in the clarification of the evolution of human pathogens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Deer / microbiology
  • Escherichia coli O157 / classification
  • Escherichia coli O157 / genetics*
  • Evolution, Molecular
  • Feces / microbiology
  • Genetic Speciation
  • Genome, Bacterial
  • Genotype
  • Humans
  • Models, Genetic
  • Multilocus Sequence Typing
  • Phylogeny
  • Polymorphism, Single Nucleotide*
  • Sequence Analysis, DNA