I recently came across an interesting article from a produce industry online trade journal (The Packer). The article discusses a new mandate from Costco that requires pathogen testing. But produce suppliers have been testing for pathogens for some time, and they routinely use diagnostic assays for this purpose. However, there is some debate on the accuracy of rapid tests that detect a broad range of pathogens as compared with PCR assays that target specific strains. Here is the full story from http://thepacker.com:
New pathogen testing requirements for produce companies supplying Costco Wholesale Corp. may be the first of their kind, but large suppliers say they were already conducting the tests.
Craig Wilson, Costco’s vice president of quality assurance and food safety, said July 18 that the company began requiring its produce suppliers to test finished products for the “Big 6” E. coli strains “a couple of months ago.”
He said the company added the rare strain O104:H4 that recently sickened more than 3,900 people in Europe to its mandatory test list “in the past two or three weeks.”
“The tests don’t make the food safer, but they do tell us if the vendors’ food safety programs are working,” Wilson said.
Representatives of two of Costco’s produce suppliers agreed with Wilson’s assessment of the role of testing. They also said none of their other customers require finished product testing.
Earthbound Farm, San Juan Bautista, Calif., began testing raw products in 2006 and finished products in 2007 in response to the E. coli outbreak in 2006. Consequently, the Costco requirement won’t add any costs or disrupt their supply chain, said Will Daniels, senior vice president of operations and organic integrity.
“We test 100% of raw and 100% of our finished products, unlike many companies that just do spot checks,” Daniels said, adding that the company’s cost for the aggressive testing program is only 3 cents per retail unit, “which we do not pass along to our customers.”
At Ready Pac Foods Inc. in Irwindale, Calif., tests for salmonella and various E. coli strains have been standard procedure for several years, said Brian Zomorodi, senior vice president of technology and quality.
Both Earthbound Farm and Ready Pac work with IEH Laboratories & Consulting Group, Lake Forest Park, Wash., which has 76 labs across the country.
More than three years ago Ready Pac and IEH partnered to open a lab onsite at one of Ready Pac’s locations in California. The lab is staffed 24 hours a day, seven days a week to help reduce delays that finished product testing can cause.
The PCR (polymerase chain reaction) testing used by both produce companies takes about 12 hours, including sample preparation time and an enrichment process — or growth period — for each sample. If tests come up positive an additional four hours are needed for confirmation.
Zomorodi and Daniels both said that so-called rapid tests may offer results in as little as 15 minutes, but the quality of the results and their accuracy are far less reliable than the PCR method.
“With the rapid tests you are looking for a broader category of organisms,” Daniels said. “There is a large class of E. coli out there and many of them don’t make you sick. So if you are using a rapid test and get a positive result you could be throwing away good product because you don’t know which strain is present.”
Mansour Samadpour, president of IEH, echoed Daniels comments about the rapid tests. Companies have to follow the rapid test with the 12-hour PCR method for strain-specific results.
DuPont’s Qualicon division markets PCR test kits to the produce industry; the company warns that rapid tests are not reliable for specific pathogen testing.
Amy Smith, technical applications and regulatory support specialist for Qualicon, said a positive from a rapid test still leaves uncertainty.
“Diagnostic tests are only useful if they find the organisms you are looking for,” Smith said. “The enrichment step is the key in any of these kinds of tests.”
Smith said Qualicon is working on a test for the rare E. coli strain that hit Europe, but because of the evolutionary nature of the pathogen the company is waiting to see how it develops to create the most accurate test possible.
Similarly, BioControl Systems, a multinational company specializing in food safety testing with offices in Bellevue, Wash., and seven other countries, also has a test for the O104:H4 strain in the works. Anita Kressner, vice president for marketing, said the company hopes to have the new test available by the fourth quarter this year.
Samadpour said July 19 that IEH has already developed a test for O104:H4, which it made available to customers beginning two weeks ago.