The attaching and effacing (A/E) pathogens enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are major human pathogens, and the diseases they effect cause a significant public health risk. The related Citrobacter rodentium is a natural mouse pathogen that is used as an in vivo model for A/E lesion forming pathogens, including EPEC and EHEC. The major aim of this fellowship application is to address how C. rodentium adapts its metabolism to exploit the metabolite environment provided by the resident microbiota to promote successful colonization.
The specific aims are: 1. The hypothesis that C. rodentium can respond to its nutritional environment by modulating its virulence will be tested. This will be accomplished by screening for the induction of virulence genes with a luciferase reporter strain of C. rodentium after exposure to hundreds of unique nutrients on Biolog Phenotype MicroArray plates. The influence of disaccharides and fatty acids upon virulence gene induction will also be tested. Finally, mutations will be made in critical genes involved in the catabolism and transport of the nutrients found to affect virulence gene induction, and then tested for their ability to induce virulence and colonize the host. 2. The route of infection with C. rodentium begins by ingestion, followed by early colonization of the cecum and subsequent colonization of the colon. The hypothesis that the metabolites provided by the resident microbiota influence susceptibility to C. rodentium colonization in the cecum will be tested. The composition of the microbiota will be shifted with antibiotics and then tested for susceptibility to colonization. The dominant nutrients present in the cecum and small bowel of these mice will be identified by metabolomics and fatty acid analysis, and directly tested for their influence upon colonization.

Public Health Relevance

Enteric pathogens cause significant morbidity and mortality to the public, yet as of late these pathogens have become increasingly resistant to antimicrobial therapies. Completion of this fellowship will generate substantial new leads to target the mechanisms pathogenic bacteria undertake to respond their growth environment, a promising opportunity to enhance public health in a novel way.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32AI085761-03
Application #
8310766
Study Section
Special Emphasis Panel (ZRG1-F13-C (20))
Program Officer
Korpela, Jukka K
Project Start
2010-09-01
Project End
2014-02-01
Budget Start
2012-09-01
Budget End
2014-02-01
Support Year
3
Fiscal Year
2012
Total Cost
$46,092
Indirect Cost
Name
University of British Columbia
Department
Type
DUNS #
251949962
City
Vancouver
State
BC
Country
Canada
Zip Code
V6 1-Z3
Collins, James W; Keeney, Kristie M; Crepin, Valerie F et al. (2014) Citrobacter rodentium: infection, inflammation and the microbiota. Nat Rev Microbiol 12:612-23
Keeney, Kristie M; Finlay, B Brett (2011) Enteric pathogen exploitation of the microbiota-generated nutrient environment of the gut. Curr Opin Microbiol 14:92-8