Editor's Note: An earlier version of this article incorrectly stated that US Foods is a distributor to McDonald's. According to McDonald's and the FDA, Taylor Farms supplied onions to the affected McDonald's restaurants.
Produce company Taylor Farms has issued a voluntary recall on raw onions in connection with a deadly E. coli outbreak linked to McDonald's quarter pounders. The U.S. Food and Drug Administration has said that raw slivered onions and the beef patties are the focus of their investigation as potential E. coli sources, but also indicated that preliminary data suggests the onions are "a likely source of contamination." Taylor Farms told Bloomberg when the recall was announced that it had not found traces of E. coli in its onions.
In a separate but related recall notice from restaurant supplier US Foods obtained by ABC News, the company advised its customers that Taylor Farms, one of its suppliers, announced a recall out of an abundance of caution on four raw onion products "due to potential E. coli contamination."
"Our records show that affected product may have been sent to your location. It is urgent that you stop using affected product as soon as possible," the notice read.
"US Foods takes food safety very seriously. Out of an abundance of caution, Taylor Farms, one of our third-party suppliers, has issued a voluntary recall for specific onion products produced out of their Colorado facility. The Taylor Farms recall impacts six US Foods distribution centers located in Colorado, Kansas, Nebraska and New Mexico. US Foods operates 70+ distribution centers across the country. As aligned with our rigorous recall process, we have contacted all impacted US Foods customers with appropriate recall instructions," the company said in a statement.
US Foods told ABC News that it does not distribute Taylor Farms slivered onions to McDonald's.
McDonald's confirmed in a statement to ABC News that Taylor Farms is the supplier of the sliced onions the fast-food chain removed, but it is unclear whether Taylor Farms provides its products directly to McDonald's or through an intermediary.
Four different products were included in the recall: 30-pound bags of peeled jumbo yellow onions, 4-5-pound bags of 3/8-inch diced fresh yellow onions, 5-pound bags of fresh diced yellow onions, and 6-5-pound bags of whole, peeled yellow onions.
"If you find any of the affected product, please record the number of cases and then destroy the product," the U.S. Foods notice stated.
As of the time of publication, the Centers for Disease Control and Prevention has reported 49 cases of E. coli with 10 hospitalizations and one death across 10 states linked to McDonald's Quarter Pounders.
Health officials have said they expect the number of sick people to grow.
"This is a fast-moving outbreak investigation. Most sick people are reporting eating Quarter Pounder hamburgers from McDonald's and investigators are working quickly to confirm which food ingredient is contaminated," the agency stated in a food safety alert. "McDonald's has pulled ingredients for these burgers, and they won't be available for sale in some states."
As a result, McDonald's removed the Quarter Pounder from menus in the states affected by the outbreak, which accounts for 20% of the U.S. locations.
McDonald's announced Wednesday that it had proactively removed two ingredients from stores across two impacted regions, but the company's leadership team assured that a majority of other menu items are not impacted, according to the CDC investigation.
"Other beef products at McDonald's, including the Cheeseburger, Hamburger, Big Mac, McDouble and the Double Cheeseburger, are not impacted," McDonald's USA president Joe Erlinger said Wednesday.
A spokesperson for McDonald's said either fresh onions, which came from one supplier, or beef patties used for the Quarter Pounder could be behind the outbreak.
If onions are found to be the source of the E. coli outbreak, it would be the first time onions have ever been a carrier for this particular strain of the bacteria, company spokespeople said on Wednesday.
The spokespeople also reiterated that onions used in the Quarter Pounders, as identified by CDC tracing data, came from suppliers that also test for E. coli.
Burger King released a statement Thursday saying, "There is no crossover with McDonald's for the vast majority of our onion facilities," but added, "About 5% of our restaurants do receive onions distributed from the Taylor Farms Colorado facility."
"Despite no contact from health authorities and no indications of illness, we proactively asked our 5% of restaurants who received whole onions distributed by this facility to dispose of them immediately two days ago and we are in the process of restocking them from other facilities," Burger King said.
ABC News' Taylor Dunn contributed to this report.
