Document Detail

Human microbiota-secreted factors inhibit shiga toxin synthesis by enterohemorrhagic Escherichia coli O157:H7.
MedLine Citation:
PMID:  19064636     Owner:  NLM     Status:  MEDLINE    
Escherichia coli O157:H7 is a food-borne pathogen causing hemorrhagic colitis and hemolytic-uremic syndrome, especially in children. The main virulence factor responsible for the more serious disease is the Shiga toxin 2 (Stx2), which is released in the gut after oral ingestion of the organism. Although it is accepted that the amount of Stx2 produced by E. coli O157:H7 in the gut is critical for the development of disease, the eukaryotic or prokaryotic gut factors that modulate Stx2 synthesis are largely unknown. In this study, we examined the influence of prokaryotic molecules released by a complex human microbiota on Stx2 synthesis by E. coli O157:H7. Stx2 synthesis was assessed after growth of E. coli O157:H7 in cecal contents of gnotobiotic rats colonized with human microbiota or in conditioned medium having supported the growth of complex human microbiota. Extracellular prokaryotic molecules produced by the commensal microbiota repress stx(2) mRNA expression and Stx2 production by inhibiting the spontaneous and induced lytic cycle mediated by RecA. These molecules, with a molecular mass of below 3 kDa, are produced in part by Bacteroides thetaiotaomicron, a predominant species of the normal human intestinal microbiota. The microbiota-induced stx(2) repression is independent of the known quorum-sensing pathways described in E. coli O157:H7 involving SdiA, QseA, QseC, or autoinducer 3. Our findings demonstrate for the first time the regulatory activity of a soluble factor produced by the complex human digestive microbiota on a bacterial virulence factor in a physiologically relevant context.
Thibaut de Sablet; Christophe Chassard; Annick Bernalier-Donadille; Marjolaine Vareille; Alain P Gobert; Christine Martin
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Publication Detail:
Type:  Journal Article     Date:  2008-12-08
Journal Detail:
Title:  Infection and immunity     Volume:  77     ISSN:  1098-5522     ISO Abbreviation:  Infect. Immun.     Publication Date:  2009 Feb 
Date Detail:
Created Date:  2009-01-19     Completed Date:  2009-02-20     Revised Date:  2013-06-04    
Medline Journal Info:
Nlm Unique ID:  0246127     Medline TA:  Infect Immun     Country:  United States    
Other Details:
Languages:  eng     Pagination:  783-90     Citation Subset:  IM    
INRA, Institut National de la Recherche Agronomique, UR454 Unité de Microbiologie, Centre de Recherche de Clermont-Ferrand/Theix, 63122 Saint-Genès-Champanelle, France.
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MeSH Terms
Bacteroides / metabolism*
Cecum / microbiology
Child, Preschool
Escherichia coli O157 / metabolism*
Feces / microbiology
Gastrointestinal Contents / microbiology
Gene Expression Regulation, Bacterial / physiology
Quorum Sensing
Rats, Inbred F344
SOS Response (Genetics)
Shiga Toxin 2 / antagonists & inhibitors,  biosynthesis*
Transcription, Genetic
Young Adult
Reg. No./Substance:
0/Shiga Toxin 2

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