Document Detail

Acid-stress-induced changes in enterohaemorrhagic Escherichia coli O157 : H7 virulence.
MedLine Citation:
PMID:  19497950     Owner:  NLM     Status:  MEDLINE    
Enterohaemorrhagic Escherichia coli (EHEC) O157 : H7 is naturally exposed to a wide variety of stresses including gastric acid shock, and yet little is known about how this stress influences virulence. This study investigated the impact of acid stress on several critical virulence properties including survival, host adhesion, Shiga toxin production, motility and induction of host-cell apoptosis. Several acid-stress protocols with relevance for gastric passage as well as external environmental exposure were included. Acute acid stress at pH 3 preceded by acid adaptation at pH 5 significantly enhanced the adhesion of surviving organisms to epithelial cells and bacterial induction of host-cell apoptosis. Motility was also significantly increased after acute acid stress. Interestingly, neither secreted nor periplasmic levels of Shiga toxin were affected by acid shock. Pretreatment of bacteria with erythromycin eliminated the acid-induced adhesion enhancement, suggesting that de novo protein synthesis was required for the enhanced adhesion of acid-shocked organisms. DNA microarray was used to analyse the transcriptome of an EHEC O157 : H7 strain exposed to three different acid-stress treatments. Expression profiles of acid-stressed EHEC revealed significant changes in virulence factors associated with adhesion, motility and type III secretion. These results document profound changes in the virulence properties of EHEC O157 : H7 after acid stress, provide a comprehensive genetic analysis to substantiate these changes and suggest strategies that this pathogen may use during gastric passage and colonization in the human gastrointestinal tract.
B House; J V Kus; N Prayitno; R Mair; L Que; F Chingcuanco; V Gannon; D G Cvitkovitch; D Barnett Foster
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-06-04
Journal Detail:
Title:  Microbiology (Reading, England)     Volume:  155     ISSN:  1350-0872     ISO Abbreviation:  Microbiology (Reading, Engl.)     Publication Date:  2009 Sep 
Date Detail:
Created Date:  2009-09-01     Completed Date:  2009-12-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9430468     Medline TA:  Microbiology     Country:  England    
Other Details:
Languages:  eng     Pagination:  2907-18     Citation Subset:  IM    
Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada.
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MeSH Terms
Bacterial Adhesion / drug effects
Cell Line
Epithelial Cells / microbiology,  physiology
Erythromycin / pharmacology
Escherichia coli Infections / metabolism,  microbiology*
Escherichia coli O157 / drug effects,  pathogenicity*,  physiology
Gene Expression Profiling
Host-Pathogen Interactions / drug effects
Hydrogen-Ion Concentration
Protein Synthesis Inhibitors / pharmacology
Shiga Toxins / biosynthesis
Stress, Physiological*
Virulence Factors / biosynthesis,  genetics
Reg. No./Substance:
0/Protein Synthesis Inhibitors; 0/Shiga Toxins; 0/Virulence Factors; 114-07-8/Erythromycin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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