News about E. coli and Salmonella outbreaks from fast food restaurants bring to mind all sorts of gruesome images about what happens to our burgers before they're served.
In truth, many of the vegetables that top our burgers acquire the little nasties while they are growing, well before they hit the bun. "What we've found up to this point is that most contamination is occurring while plants are still growing in the field," said Jeri D. Barak of the USDA in a press release.
Barak's research shows that human pathogens use specific genes to colonize the plant early and create a bond with the vegetable. That bond makes it harder to separate the pathogens from the plant when it is older, and ready to be picked for our culinary pleasure.