"The good news is: Five days ago, we changed our lettuce supplier, and all our produce suppliers, for all our Northeast stores," Creed said on CNBC. He said he has continued to eat at Taco Bell restaurants since a total of 71 people fell sick because of an E. coli outbreak linked to the company's restaurants. No new cases have been reported since Dec. 6.
"This is an ingredient issue," Creed said. "It has nothing to do with the hygiene of our restaurants."
The company, which is a unit of Yum Brands , has been working closely with the Food & Drug Administration and the Centers for Disease Control to identify the source of the outbreak.
U.S. health officials said on Wednesday that Taco Bell's lettuce became the focus of the investigation following a statistical analysis of what people had eaten before they fell ill. Many also ate cheddar cheese and beef, and those supply chains are also being investigated, officials said.
"It would be folly at this point to drop the cheese completely. It's critical to keep all options open," said David Acheson, Chief Medical Officer of the FDA's Center for Food Safety and Applied Nutrition.
On Wednesday, Creed said health officials had told the chain that cheese and beef were unlikely to have caused the outbreak because the cheese is pasteurized and because of the way the beef is prepared.
But none of the other ingredients used at Taco Bell appeared to be associated with the outbreak, Acheson said adding no ingredients have tested positive for the E.coli strain blamed for the outbreak. "The fact that the testing is negative does not put me off," he said.
Creed said it was "too early" to determine the financial impact of the outbreak.
Neither Taco Bell nor the FDA would disclose the name of the company that supplied the lettuce to Taco Bell restaurants in New Jersey, New York, Pennsylvania and Delaware. Taco Bell said that at certain points during the outbreak 90 restaurants were closed.
Creed said only that the lettuce was grown in the Western United States and that Taco Bell buys less than 20% of the lettuce produced by the supplier in question.
Before lettuce arrives at Taco Bell restaurants, it is rinsed multiple times, shredded and packed in sealed containers, Creed said. It is not rinsed at the restaurants.
Last week, Taco Bell banned green onions after an earlier test, since discredited, showed they may have been the source of contamination. The company has no plans to put green onions back on the menu. "We just don't want to take any chances at this time," Creed said.
Food safety officials said restaurants appeared to be safe. "We are fairly confident that the contaminated product is not being distributed or served at this point," said Christopher Braden, Medical Epidemiologist at the Centers for Disease Control and Prevention. Braden conducted the statistical study.
Health officials also said that the Taco Bell outbreak was not believed to be related to E.coli infections in Minnesota and Iowa that have been linked to Taco John's restaurants.
To help analyze its food safety practices, Creed said the company hired food safety expert Mike Doyle of the University of Georgia, who informed the company that its standards "are some of the highest in the industry." The company has not changed those standards in response to the outbreak, he said.
On CNBC, Creed said, "We have stringent safety standards in place."
He plans to lead an industry coalition to investigate the produce supply chain and find ways to make it safer and to reassure the public that it is safe.
"It is a much bigger issue than just Taco Bell," he said.