McDonald's said testing ruled out Quarter Pounder patties as the source of the E. coli in the US

The test determined that beef patties as a source of poisoning by E. coli has been tied to McDonald's Quarter Pounders, the company said Sunday. It will resume selling the Quarter Pounder next week.

The US Food and Drug Administration (FDA) continues to believe that leftover onions from a single supplier are the likely source of the contamination, McDonald's said.

As of Friday, the outbreak has spread to at least 75 sick people in 13 states, health officials said. A total of 22 have been admitted to the hospital, and two have been diagnosed with serious kidney disease, said the Centers for Disease Control and Prevention (CDC). One person died in Colorado.

Preliminary data analyzed by the FDA indicated that raw onions used in burgers were “a source of contamination,” the agency said. McDonald's confirmed that Taylor Farms, a California-based producer, was supplying the fresh onions used in the restaurants involved in the outbreak and that they were coming from a facility in Colorado Springs, Colo.

The 900 McDonald's restaurants that regularly receive sliced ​​onions from Taylor Farms' Colorado Springs facility will resume selling Quarter Pounders without sliced ​​onions, McDonald's said.

Taylor Farms said Friday it has recalled yellow onions shipped to customers at its Colorado facility and is continuing to work with the CDC and FDA as they investigate.

This outbreak involves infection with E. coli 0157:H7, a type of bacteria that produces a deadly toxin. It causes about 74,000 illnesses in the United States every year, resulting in more than 2,000 hospitalizations and 61 deaths each year, according to the CDC.

A spokesperson for McDonald's Canada said the concern of E. coli does not spread to Canadian territories.