Prescott's Microbiology 8th Edition by Joanne Willey, Linda Sherwood, Christopher J. Woolverton, Lansing Prescott, John Harley, Donald Klein

Exercise 3

Enterohemorrhagic E. coli (EHEC) 0157:H7 has caused severe food poisoning outbreaks in the United States and elsewhere. In order for EHEC to colonize the host intestinal epithelium, it must have a mechanism for attachment. When EHEC are grown in vitro with cultured human epithelial cells, the bacteria form fibrils that attach them to the epithelial cells. After 3 hours of incubation, changes in the morphology of the human cells consistent with the changes seen during infection are noted. Based solely on their function, would you hypothesize that these fibrils are flagella, fimbriae, or pili? Explain your answer. How would you determine the identity of the fibrils? How would you determine if they were necessary for infection?

Step 1 of 4

The fibrils seen on Escherichia coli O157:H7 that contribute to the binding of the organism to intestinal epithelial cells are likely fimbriae. Flagella are structures utilized for motility and sex pili are used for transferring DNA between cells. The phenotype we are looking for is adherence. Fimbriae contain adhesion proteins at the end of the fibril, which allow for interaction of the microbe to a surface.