Whiteley Exam 5 - Whiteley Exam 5 BIO 339/391R Name: _ UT...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Whiteley Exam 5 BIO 339/391R Name: ________________________________ UT EID: ____________________ 1. You are interested in understanding the impact that the normal flora has on colonization of the colon by pathogenic E. coli O157:H7. To study this problem, you use a germ-free mouse model of infection. Your first goal is to determine if commensal (non-pathogenic ) strains of E. coli will protect mice from colonization by E. coli O157:H7. To examine this you do two experiments: a. You orally inoculate equal numbers (10 5 ) of commensal E. coli and E. coli O157:H7 into the mouse at the same time. After 24 hours you recover approximately 10 8 of each strain from the colon. b. You first orally inoculate the mouse with 10 5 commensal E. coli and after 24 hours you recover approximately 10 8 commensal E. coli from the colon. You then add 10 5 E. coli O157:H7. After another 24 hours you recover 10 8 commensal E. coli and 10 7 E. coli O157:H7. Explain these results. (15 points) In the first experiment when equal amounts of commensal E.coli and pathogenic E.coli were inoculated into the mouse at the same time, the commensal E.coli did not protect the mouse from colonization and both strains of E.coli were able to replicate in the mouse. This was because the commensal E.coli had yet to occupy a niche in the mouse and had to compete with the pathogenic E.coli for a niche. In the second experiment the commensal E.coli was administered first and was able to occupy a niche inside the mouse. When the pathogenic E.coli was administered 24 hours later it was still able to replicate in the mouse, but not as much as the commensal E.coli . This probably had to do with the commensal E.coli having already occupying its niche and now being able to protect the mouse by killing off some of the pathogenic E,coli. In a separate set of experiments, you show that commensal E. coli can prevent colonization of a different pathogenic E. coli (EPEC). You hypothesize that lactic acid fermentation is required for commensal E. coli to prevent colonization of EPEC. Design an experiment to test this hypothesis. (15 points) To begin with you would perform the experiment without any type of bacteria that would able to undergo lactic acid fermentation. You would administer the pathogenic
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 06/10/2011 for the course BIO 339 taught by Professor Georgiou during the Fall '07 term at University of Texas at Austin.

Page1 / 4

Whiteley Exam 5 - Whiteley Exam 5 BIO 339/391R Name: _ UT...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online