WASHINGTON (AP) -- The Food and Drug Administration said Thursday the strain of E. coli found in a sample of raw cookie dough collected at a Nestle USA manufacturing plant does not match the strain that has been linked to a 30-state outbreak, and they aren't sure how the dough was contaminated.
The FDA and the federal Centers for Disease Control have been investigating whether the cookie dough was the source of the E. coli outbreak which has sickened at least 69 people in about 30 states.
E. coli is a potentially deadly germ that can cause bloody diarrhea, dehydration and, in the most severe cases, kidney failure.
Last month, Nestle voluntarily recalled all Toll House refrigerated cookie dough products made at its Danville, Virginia, factory after the FDA told Nestle it suspected consumers may have been exposed to E. coli bacteria after eating the dough raw.
On June 29, the FDA confirmed evidence of E. coli O157:H7 in a retained production sample of 16.5 oz. (467 gram) Nestle Toll House refrigerated chocolate chip cookie dough bar. But on Thursday, FDA spokesman Mike Herndon said tests on the dough, which came from an unopened package, show the strains of E. coli don't match the E. coli strain linked to the outbreak.
That could mean the dough may have been contaminated with multiple strains. But neither the FDA nor Nestle has discovered a probable source.
The FDA is working with the Glendale, California-based unit of Switzerland-based Nestle SA on the investigation, which Herndon said was ongoing. Nestle said that during federal investigators' visit to the Danville plant, which lasted more than a week, the inspection didn't turn up a connection to E. coli.
Nestle said inspectors observed that a gate valve used on a hopper for dry ingredients required a smoother and more polished surface to allow for easier cleaning. The FDA also noted condensation dripping from a refrigeration pipe onto a large metal spatula used to scrape cookie dough from the mixer. Both of the items were corrected, the company said.
Nestle said more than 1,000 tests have been performed at the Danville facility, with the company dismantling its production lines for thorough inspection, testing equipment and ingredients, and reviewing its quality and food safety procedures.