Monitoring pathogens for their infectious capacity in humans may not be the best approach to minimize the risk of foodborne outbreaks, say researchers who spoke during the 2014 ASM General Meeting in Boston last May.

Other factors come into play—particularly, the ability of some pathogens to colonize food sources, proliferate, and thus amplify the inoculating dose delivered to consumers is critically important, they say. Colonizing food sources also can alter gene expression, increasing pathogenicity and decreasing the infectious dose. Understanding this “ecology” could prove crucial for predicting and preventing foodborne outbreaks.

Greens and produce are major sources of foodborne pathogens, many of which can thrive when greens are cut and processed during food preparation. Produce is the leading source of foodborne illness commonly caused by Salmonella enterica or Escherichia coli O157:H7 on leafy greens, according to Maria Brandl of the U.S. Department of Agriculture (USDA) in Albany, Calif.

“The continuous rise in the number of outbreaks of foodborne illness linked to fresh fruit and vegetables challenges the notion that enteric pathogens are defined mostly by their ability to colonize the intestinal habitat,” she says. “Enteric pathogens utilize diverse and overlapping strategies to interact with plants and their microflora, and to successfully colonize vertebrate hosts.”