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United States Department of Agriculture

Agricultural Research Service

Research Project: PREVENTION AND CHARACTERIZATION OF PERSISTENT COLONIZATION BY E. COLI O157:H7 AND OTHER SHIGA TOXIN-PRODUCING E. COLI (STEC) IN CATTLE Title: Molecular insights into the unique phenotypes exhibited by super shed shiga toxin producing Escherichia coli O157

Authors
item Moreau, Mathew -
item Katani, Robab -
item Cote, Rebecca -
item Kudva, Indira
item Brandl, Maria
item Carter, Michelle
item Arthur, Terrance
item Debroy, Chitrita -
item Goodfield, Laura -
item Li, Lingling -
item Kapur, Vivek -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 21, 2014
Publication Date: N/A

Technical Abstract: Shiga toxin producing Escherichia coli (STEC) serovar O157:H7 is a major foodborne pathogen that can cause bloody diarrhea and life threatening hemolytic uremic syndrome in humans. Asymptomatic cattle are colonized with E. coli O157:H7 at the mucosal interface of the recto-anal junction (RAJ). Super shedding (SS) is a phenomenon that has been reported in some cattle shedding O157:H7 at an amount greater than 104 CFU/g of feces, 100-1000 times greater than commonly observed. To better understand the molecular genetic mechanisms associated with this unique phenotype and, in the long-term, investigate the phenomenon of super-shedding, our laboratory recently sequenced and characterized the complete genome of SS17, a representative SS-isolate that shows a strongly adherent and aggregated phenotype on recto-anal squamous epithelial (RSE) cells. Subsequently, genes selected for study in SS17 were selected for their potential functions and/or the presence of non-synonymous SNPs and other genetic alterations. The results of our analysis show that deletions of ompA, eivA, yfaL, and wzzB in the reference strain EDL933 resulted in a phenotypic switch from diffuse and moderate adherence in the RSE model to strong adherence and aggregation, similar to SS17. Furthermore, SS17 exhibited enhanced attachment to the surface of spinach leaves and biofilm formation in spinach leaf lysates compared with EDL933. The genes ompA, cah, and yfaL are all required for SS17’s enhanced biofilm formation in spinach extract. Together, these investigations are beginning to help establish the functional role of various genes and their contribution to animal colonization, adherence to produce, environmental survival, transmission and eventual infection of human hosts by SS isolates of E. coli.

Last Modified: 11/23/2014
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