Shoppers changed their buying habits Saturday as spinach was pulled from grocery store shelves because of the outbreak of E. coli bacteria that had killed one person and sickened nearly 100 others.

Natural Selection Foods LLC recalled its packaged spinach throughout the United States, Canada and Mexico as a precaution after federal health officials said some of those hospitalized reported eating brands of prepackaged spinach distributed by the company.

The officials stressed that the bacteria had not been isolated in products sold by the holding company, based in San Juan Bautista, Calif., and known for Earthbound Farm and other brands. As the investigation continues, other brands may be implicated, officials said.

At a Safeway grocery in San Francisco's Potereo Hill neighborhood, many of bagged produce shelves were empty Saturday. Anna Cairns said she had to settle for bags of iceberg green lettuce and Caesar salad, instead of her normal salad mix, which contained spinach.

"I have a bag of spinach in my refrigerator I need to throw away," said Cairns, 59, of San Francisco.

Marina Zecevic, 49, of West Los Angeles, shopping at a Trader Joe's, said she made the mistake of serving creamed spinach to her kids the day the story broke.

"My sons started accusing me of premeditated murder," she said.

She felt the contamination issue was overblown.

"The minute we get the all clear, the spinach is back on the table," she said.

The spinach, grown in California, could have been contaminated in the field or during processing, according to the Centers for Disease Control and Prevention.

About 74 percent of the fresh market spinach grown in the U.S. comes from California, according to the California Farm Bureau Federation. There have been previous bacterial contamination outbreaks linked to spinach and lettuce grown in the state.

Wisconsin accounted for 29 illnesses, about one-third of the cases, including the lone death, a 77-year-old woman who died of kidney failure.

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 CDC.

"We are very, very upset about this. What we do is produce food that we want to be healthy and safe for consumers, so this is a tragedy for us," Natural Selection spokeswoman Samantha Cabaluna said.

The CDC warned that boiling contaminated spinach can kill the bacteria but washing won't eliminate it.

At a Stop and Shop supermarket in Meriden, Conn., Michelle Bookey said she frequently buys spinach for salads for her dieting husband but plans to cook it from now on.

"It worries me. I don't even want to buy lettuce," said Bookey, 36.

Earthbound Farm, which claims it pioneered the retail market in pre-washed, bagged salads in 1986, says its spinach and other products are in 74 percent of U.S. grocery stores.

It also sells spinach to restaurants and other establishments that serve food. The National Restaurant Association said members were pulling spinach from their menus.

The recall earned the praise of Tom Stenzel, president and chief executive officer of the United Fresh Produce Association.

"The FDA investigation and the voluntary action taken by Natural Selection Foods LLC help narrow concern about any continuing risk, and begins to ensure that product that may be potentially contaminated is removed completely from the food supply," Stenzel said in a statement.

A Seattle law firm said it planned to add Natural Selection Foods on Monday to federal lawsuits previously filed in Wisconsin and Oregon that named other spinach producers.