Recycling of Shiga Toxin 2 Genes in Sorbitol-Fermenting Enterohemorrhagic Escherichia coli O157:NM
- 1 January 2008
- journal article
- Published by American Society for Microbiology in Applied and Environmental Microbiology
- Vol. 74 (1), 67-72
- https://doi.org/10.1128/aem.01906-07
Abstract
Using colony blot hybridization with stx(2) and eae probes and agglutination in anti-O157 lipopolysaccharide serum, we isolated stx(2)-positive and eae-positive sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:NM (nonmotile) strains from initial stool specimens and stx-negative and eae-positive SF E. coli O157:NM strains from follow-up specimens (collected 3 to 8 days later) from three children. The stx-negative isolates from each patient shared with the corresponding stx(2)-positive isolates fliC(H7), non-stx virulence traits, and multilocus sequence types, which indicates that they arose from the stx(2)-positive strains by loss of stx(2) during infection. Analysis of the integrity of the yecE gene, a possible stx phage integration site in EHEC O157, in the consecutive stx(2)-positive and stx-negative isolates demonstrated that yecE was occupied in stx(2)-positive but intact in stx-negative strains. It was possible to infect and lysogenize the stx-negative E. coli O157 strains in vitro using an stx(2)-harboring bacteriophage from one of the SF EHEC O157:NM isolates. The acquisition of the stx(2)-containing phage resulted in the occupation of yecE and production of biologically active Shiga toxin 2. We conclude that the yecE gene in SF E. coli O157:NM is a hot spot for excision and integration of Shiga toxin 2-encoding bacteriophages. SF EHEC O157:NM strains and their stx-negative derivatives thus represent a highly dynamic system that can convert in both directions by the loss and gain of stx(2)-harboring phages. The ability to recycle stx(2), a critical virulence trait, makes SF E. coli O157:NM strains ephemeral EHEC that can exist as stx-negative variants during certain phases of their life cycle.This publication has 65 references indexed in Scilit:
- Insertion Site Occupancy by stx 2 Bacteriophages Depends on the Locus Availability of the Host Strain ChromosomeJournal of Bacteriology, 2007
- Grazing protozoa and the evolution of the Escherichia coli O157:H7 Shiga toxin-encoding prophageProceedings. Biological sciences, 2007
- Shiga Toxin Gene Loss and Transfer In Vitro and In Vivo during Enterohemorrhagic Escherichia coli O26 Infection in HumansApplied and Environmental Microbiology, 2007
- Greater Diversity of Shiga Toxin-Encoding Bacteriophage Insertion Sites among Escherichia coli O157:H7 Isolates from Cattle than in Those from HumansApplied and Environmental Microbiology, 2007
- Shiga Toxin and Shiga Toxin-Encoding Phage Do Not Facilitate Escherichia coli O157:H7 Colonization in SheepApplied and Environmental Microbiology, 2007
- Molecular and phenotypic profiling of sorbitol-fermenting Escherichia coli O157:H− human isolates from FinlandClinical Microbiology & Infection, 2006
- In Vivo Transduction of an Stx-Encoding Phage in RuminantsApplied and Environmental Microbiology, 2006
- Sex and virulence in Escherichia coli: an evolutionary perspectiveMolecular Microbiology, 2006
- Human Neutrophils and Their Products Induce Shiga Toxin Production by Enterohemorrhagic Escherichia coliInfection and Immunity, 2001
- The Complete Genome Sequence of Escherichia coli K-12Science, 1997