Tests for foodborne pathogens in which a culture is not grown in a lab may be necessary for produce companies, but they can’t replace traditional culture tests, industry leaders and government officials say.
Nonculture diagnostic tests have been around since the early 1980s, said David Gombas, senior vice president of food safety and technology for the Washington D.C.-based United Fresh Produce Association.
But there has been a recent push, Gombas said, to use them to replace culture tests that the Centers for Disease Control and Prevention, the Food and Drug Administration and other agencies and organizations rely on to accurately diagnose cases of salmonella, E. coli and other foodborne illnesses.
That trend was highlighted in a recent article in Scientific America magazine, which found that many clinics and state-run labs are turning to nonculture tests, which are faster than culture tests.
They’re faster, but are they better?
“Right now, the answer is no,” Gombas said. “CDC, FDA, and those in the produce industry I talk to — they want a live bug.”
A live bug is the result of growing a culture, which can take 18 to 24 hours in a lab, Gombas said. Some of the rapid nonculture tests, by contrast, can be done in 20 minutes.
For many fresh produce companies, like Earthbound Farm, San Juan Batista, Calif., rapid nonculture tests are a necessity, said Will Daniels, Earthbound’s senior vice president of operations and organic integrity.
“Without them, we wouldn’t be able to do what we do,” Daniels said. “A culture is a three to five day process. We can’t fit that into our system.”
Earthbound Farms tests every product it ships. If it relied on culture tests and had to wait three to five days to ship, it would need to have five to six days’ worth of inventory on hand at any given time, Daniels said.
As it is, the company’s warehouse is packed with just a day’s worth of inventory, he said. And of course shelf life would suffer significantly once product did finally ship.
“Speed is only a benefit in these things,” Daniels said.
Nevertheless, Daniels understands that CDC needs culture tests to do its epidemiology tests. Likewise, Gombas realizes that individual companies don’t have the time to make cultures.
“For places that have to be fast, it works,” Gombas said. “But when you have to be right, maybe not.”