“Consumers will conclude that these people have not done anything in spite of what they’ve been saying, and that becomes a credibility issue,” he said. “For a company like Chipotle, which talks a lot about the integrity of its food, that’s seriously damaging.”

Today” show to apologize to the people who became sick most recently. “I’m sorry for the people who got sick. They’re having a tough time and I feel terrible about that,” Mr. Ells said in an interview.

The company’s shares dropped $19.07, to $522.01, after the new outbreak came to light. The stock is down 30 percent from its high of $757.77 in August.

Chipotle says it is working to put in place programs to monitor the safety of each of the 68 ingredients it uses, using methods like high-resolution testing and additional food-safety training for its employees

The same bacteria has sickened 53 people in eight other states

60 samples of every 2,000 pounds of steak will be tested before it's sent to stores.

"Food With Integrity"

Onions will be dipped in boiling water to kill germs before they're chopped. Raw chicken will be marinated in resealable plastic bags, rather than in bowls. Cilantro will be added to freshly cooked rice so the heat gets rid of microbes in the garnish.

So they will remain chopped on in restaurants, along with lemons, limes, and jalapenos. All will now be blanched to kill germs.

No single food item has been identified as a source of illness.

The restaurant chain is also increasing food safety training of its employees and making improvements to its ingredient testing

More E. coli cases linked to Chipotle; may be a different outbreak

Symptoms, which include diarrhea and abdominal pain, usually begin two to eight days after a person has been exposed to the bacteria and resolve within a week. Some cases are severe and patients can develop hemolytic uremic syndrome, or HUS, which is a type of kidney failure. There have been no cases of HUS or deaths from this outbreak, although 20 of those who have become ill have been hospitalized.