Chapter 41, Problem 7CHI

Following recent outbreaks of E. coli O157:H7 associated with leafy vegetables, there has been a need to better understand the growth of this pathogen on vegetables. To that end, a study was performed to compare the colonization and growth of E. coli O157:H7 on lettuce. In this study, the success of the microbe on intact leaves was compared with regions that had been mechanically damaged by shredding or bruising. Indeed, even within 4 hours after inoculation, there was a marked increase in microbial growth on the injured surfaces of the lettuce.

Why do you think this was the case? If you were to perform this study (or one similar to it), how would you quantify E. coli colonization? If you were able to repeat and extend these findings, what kinds of recommendations might you make to the vegetable producers? To consumers?