title: Identification of intermediate in evolutionary model of enterohemorrhagic Escherichia coli O157.
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.
authors.affiliation: Institute for Hygiene and National Consulting Laboratory on Hemolytic Uremic Syndrome, Münster, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Jenke
authors.forename: Shana R
authors.initials: SR
authors.lastname: Leopold
authors.forename: Thomas
authors.initials: T
authors.lastname: Weniger
authors.forename: Jörg
authors.initials: J
authors.lastname: Rothgänger
authors.forename: Dag
authors.initials: D
authors.lastname: Harmsen
authors.forename: Helge
authors.initials: H
authors.lastname: Karch
authors.forename: Alexander
authors.initials: A
authors.lastname: Mellmann
mesh_terms: D000818:Animals; D003670:Deer / Q000382:microbiology; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D005243:Feces / Q000382:microbiology; D049810:Genetic Speciation; D016680:Genome, Bacterial; D005838:Genotype; D006801:Humans; D008957:Models, Genetic; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA