Maccas holding the onions on Quarter Pounders while it gets a handle on E. coli outbreak

McDonald’s Quarter Pounder burgers will return to roughly 900 restaurants this week in the US after the fast-food giant pulled the menu item linked to a deadly E. coli outbreak.

Affected restaurants — roughly a fifth of the company’s US footprint — will be serving the Quarter Pounder burgers without slivered onions for the foreseeable future as health authorities continue their investigation into the source of the outbreak.

That change will affect restaurants in Colorado, Kansas and Wyoming and portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma and Utah.

“The issue appears to be contained to a particular ingredient and geography, and 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,” Cesar Pina, chief supply chain officer for McDonald’s North American operations, said in a letter sent to the company’s US system.

The Colorado Department of Agriculture’s testing did not detect E. coli in samples of the beef patties taken from restaurants in the area, according to Mr Pina.

The agency isn’t planning further tests of the company’s beef. Instead, health authorities have homed in on slivered onions used in the Quarter Pounders as the likely suspect for the outbreak.

The Food and Drug Administration is still investigating if onions produced by Taylor Farms are responsible. McDonald’s has stopped using Taylor Farms as a supplier for the ingredient indefinitely.

McDonald’s is now asking its beef suppliers to produce a new supply of the fresh beef patties used in its Quarter Pounders, Mr Pina wrote.

Customers can expect to see the menu item back in all restaurants in the coming week, although it will happen on a rolling basis, depending on delivery and resupply operations.

The Centres for Disease Control and Prevention said on Friday that the E. coli outbreak linked to McDonald’s has led to 75 cases across 13 States.

Out of 61 patients with information available, 22 have been hospitalised, and two people have developed a serious condition that can cause kidney failure, called hemolytic uremic syndrome. The agency also said previously that an older adult in Colorado died.

Based on reported cases so far, the outbreak took place between September 27 and October 11.

Over a two-week period, McDonald’s typically sells roughly one million Quarter Pounders in the affected region, according to company spokespeople.

McDonald’s USA president Joe Erlinger apologised to customers who are feeling “ill, scared or uncertain” in a video posted on the company’s website.

“On behalf of the McDonald’s system, I want you to hear from me: We are sorry,” he said.

McDonald’s is expected to report its third-quarter earnings before the bell on Tuesday. Shares of the company have fallen 7 per cent since the CDC linked the E. coli outbreak to its restaurants. The outbreak comes as McDonald’s tries to win back diners who balked at years of price increases.

For months, McDonald’s has been locked in a war with its rivals over competing value meals.

The restaurant industry broadly has seen traffic fall as inflation-weary consumers cook more at home and visit eateries less frequently.

Fast-food chains, including McDonald’s, Burger King and Wendy’s, have turned to discounts and value meals to win back customers. McDonald’s US restaurants have been offering a $US5 value meal since late June.

And earlier this month, the chain launched its Chicken Big Mac nationwide, betting that customers would be willing to pay its higher price point because of the novelty. Those moves seemed to be paying off for McDonald’s before the outbreak.

“This is somewhat of a momentum killer for them,” KeyBanc analyst Eric Gonzalez said, adding that the burger category has plenty of “capable substitutes” for McDonald’s.

Combined, McDonald’s, Burger King and Wendy’s control roughly 70 per cent of the burger quick-service restaurant segment, according to Barclays.

McDonald’s alone holds 48.8 per cent market share.

“It’s not a zero-sum game, but the burger category specifically is one of the more concentrated segments,” Mr Gonzalez said.

“If McDonald’s loses a point of sales, that’s 3 to 4 points up for grabs for Wendy’s or Burger King to capture.”