Not the beef: Testing bolsters case against California onions in McDonald’s E. coli outbreak

McDonald’s Quarter Pounders are back on the menu in hundreds of restaurants after new testing confirmed that the chain’s beef patties were not to blame for a deadly E. coli outbreak, strengthening the case that California onions served on the burgers were the culprit.

Salinas, Calif.-based produce company Taylor Farms was the onion supplier in all restaurant locations connected to the outbreak, and the fast-food chain has indefinitely halted business with it, McDonald’s has confirmed. Over the weekend, McDonald’s received test results from the Colorado Department of Agriculture that found no traces of E. coli in samples of their burger patties.

On Sunday, McDonald’s executive Cesar Piña issued a statement seeking to reassure the public that all of its products were now safe to eat.

“The issue appears to be contained to a particular ingredient and geography,� said Piña, the company’s chief supply chain officer for North America. “We remain very confident that any contaminated product related to this outbreak has been removed from our supply chain and is out of all McDonald’s restaurants.�

Since the outbreak was announced Tuesday, at least 75 people have been confirmed infected in 13 states, 22 have been hospitalized, and one has died in Colorado, according to the Centers for Disease Control and Prevention.

At least 26 people were infected in Colorado, 13 in Montana, 11 in Nebraska, five each in New Mexico and Utah, four each in Missouri and Wyoming, two in Michigan and one each in Iowa, Kansas, Oregon, Wisconsin and Washington, the CDC reported Friday. So far, no California cases have been reported.

Most people reported eating a Quarter Pounder before becoming ill, and the Food and Drug Administration focused its investigation on the burger’s beef patties and slivered onions, according to the CDC.

Last week, Taylor Farms voluntarily announced a recall on four onion products “due to potential E. coli contamination.� Several other fast-food chains have pulled the company’s onions including Burger King, Taco Bell, Kentucky Fried Chicken and Pizza Hut.

The FDA is continuing to investigate the cause of the outbreak and has yet to confirm that Taylor Farm onions are the source.

The testing over the weekend by the Colorado Department of Agriculture found no traces of E. coli in McDonald’s burger patties, ruling them out as a potential source.

The department tested multiple lots of McDonald’s brand fresh and frozen beef patties collected from various Colorado McDonald’s locations associated with the outbreak.

McDonald’s had stopped distributing Quarter Pounder beef patties to around 900 restaurants. Following the results of the Colorado department’s investigation, McDonald’s has asked its suppliers to produce a new supply of fresh beef patties for the affected restaurants and will resume selling Quarter Pounders in the coming week.

The most common E. coli symptoms include stomach cramps and diarrhea, and they typically start three to four days after ingesting the bacteria. Most people recover without treatment within a week.

In extreme cases, E. coli infections can cause hemolytic uremic syndrome, a condition that damages blood vessels in the kidneys. So far, two people have developed this complication, according to the CDC.

The last reported infection began on Oct. 10, according to the CDC, giving hope that the worst of the outbreak is over.