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Recycling of Shiga toxin 2 genes in sorbitol-fermenting enterohemorrhagic Escherichia coli O157:NM.
Appl Environ Microbiol. 2008 Jan; 74(1):67-72.AE

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.

Authors+Show Affiliations

Institute of Hygiene, University of Münster, Robert-Koch-Str. 41, 48149 Münster, Germany. mellmann@uni-muenster.deNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17981936

Citation

Mellmann, Alexander, et al. "Recycling of Shiga Toxin 2 Genes in Sorbitol-fermenting Enterohemorrhagic Escherichia Coli O157:NM." Applied and Environmental Microbiology, vol. 74, no. 1, 2008, pp. 67-72.
Mellmann A, Lu S, Karch H, et al. Recycling of Shiga toxin 2 genes in sorbitol-fermenting enterohemorrhagic Escherichia coli O157:NM. Appl Environ Microbiol. 2008;74(1):67-72.
Mellmann, A., Lu, S., Karch, H., Xu, J. G., Harmsen, D., Schmidt, M. A., & Bielaszewska, M. (2008). Recycling of Shiga toxin 2 genes in sorbitol-fermenting enterohemorrhagic Escherichia coli O157:NM. Applied and Environmental Microbiology, 74(1), 67-72.
Mellmann A, et al. Recycling of Shiga Toxin 2 Genes in Sorbitol-fermenting Enterohemorrhagic Escherichia Coli O157:NM. Appl Environ Microbiol. 2008;74(1):67-72. PubMed PMID: 17981936.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Recycling of Shiga toxin 2 genes in sorbitol-fermenting enterohemorrhagic Escherichia coli O157:NM. AU - Mellmann,Alexander, AU - Lu,Shan, AU - Karch,Helge, AU - Xu,Jian-guo, AU - Harmsen,Dag, AU - Schmidt,M Alexander, AU - Bielaszewska,Martina, Y1 - 2007/11/02/ PY - 2007/11/6/pubmed PY - 2008/2/20/medline PY - 2007/11/6/entrez SP - 67 EP - 72 JF - Applied and environmental microbiology JO - Appl Environ Microbiol VL - 74 IS - 1 N2 - 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. SN - 1098-5336 UR - https://www.unboundmedicine.com/medline/citation/17981936/Recycling_of_Shiga_toxin_2_genes_in_sorbitol_fermenting_enterohemorrhagic_Escherichia_coli_O157:NM_ L2 - http://aem.asm.org/cgi/pmidlookup?view=long&pmid=17981936 DB - PRIME DP - Unbound Medicine ER -