"We're clearly evolving and it is very important to keep an open mind whether there are other products potentially implicated," said Dr. David Acheson, the chief medical officer with the Food and Drug Administration's Center for Food Safety and Applied Nutrition.
Natural Selection Foods LLC was linked to the E. coli outbreak that has killed one person and sickened nearly 100 others. Twenty-nine people have been hospitalized, 14 of them with kidney failure. FDA officials said they had received reports of illness in 19 states.
Supermarkets across the country have pulled spinach from shelves, and consumers have tossed out the leafy green.
The officials stressed that the bacteria had not been isolated in products sold by Natural Selection Foods, a holding company based in San Juan Bautista, Calif., known for Earthbound Farm and other brands. However, multiple patients named spinach brands sold by the company in interviews with health officials, Acheson said. Other brands may yet be implicated.
Meanwhile, Natural Selection Foods voluntarily recalled its products containing spinach and is cooperating with federal and state health officials to identify the source of the contamination. Its products are sold as Rave Spinach, Natural Selection Foods, Dole, Earthbound Farm, Trader Joe's, Ready Pac and Green Harvest, among other brand names.
"We are very, very upset about this," Natural Selection Foods spokeswoman Samantha Cabaluna said Friday night. "What we do is produce food that we want to be healthy and safe for consumers, so this is a tragedy for us."
The company said consumers could call 800-690-3200 for a refund or replacement coupons for tossed-out spinach products.
State health officials received the first reports of illness Aug. 25, and the FDA was informed Wednesday, Acheson said.
The FDA warned people nationwide not to eat the spinach. Washing won't get rid of the tenacious bug, although thorough cooking can kill it.
"We're waiting for the all-clear. In the meantime, Popeye the Sailor Man and this family will not be eating bagged spinach," said Dr. William Schaffner, chairman of preventative medicine at Vanderbilt University. The Tennessee university's medical center was treating a 17-year-old Kentucky girl for E. coli infection. That case originally was listed as being from Tennessee, but federal health officials changed it to Kentucky.
Each year, consumers buy more than 500 million pounds of triple-washed raw spinach, packaged in cellophane bags and clamshell boxes.
California grows 70 percent of the country's spinach and most of that comes from the rich Salinas Valley. While farmers say they don't want anyone getting sick from their produce, the local farm bureau said the government advice not to eat any bagged spinach seems too broad, reported CBS News correspondent John Blackstone.
Wisconsin accounted for 29 illnesses, about one-third of the cases, including the lone death. The victim's son identified her Friday night as Marion Graff, 77, of Manitowoc, who died of kidney failure Sept. 7.
"We are telling everyone to get rid of fresh bagged spinach right now. Don't assume anything is over," Gov. Jim Doyle said.
Other states reporting cases were California, Connecticut, Idaho, Indiana, Kentucky, Maine, Michigan, Minnesota, New Mexico, Nevada, New York, Ohio, Oregon, Pennsylvania, Utah, Virginia, Washington and Wyoming, according to the Centers for Disease Control and Prevention.
The E. coli O157:H7 strain of the bug has sickened at least 94 people across the nation, the CDC said.
Not all strains of E. coli cause illness: E. coli O157:H7 was first recognized as a cause of illness in 1982. That strain causes an estimated 73,000 cases of infection, including 61 deaths, each year in the United States, according to the CDC.
When ingested, the bug can cause diarrhea, often with bloody stools. Most healthy adults can recover completely within a week, although some people — including the very young and old — can develop a form of kidney failure that often leads to death.
Sources of the bacterium include uncooked produce, raw milk, unpasteurized juice, contaminated water and meat, especially undercooked or raw hamburger.