CHICAGO (AP) -- U.S. officials hunted for the source of a salmonella outbreak in 17 states linked to three types of raw tomatoes, while the list of supermarkets and restaurants yanking those varieties from shelves and dishes grew.
Fast food chains such as McDonald's, Burger King and Taco Bell as well as several major grocery retailers in the U.S. voluntarily withdrew red plum, red Roma or round red tomatoes unless they were grown in certain states and countries.
In addition, officials at the Los Angeles Unified School District -- the nation's second largest -- said Monday they have ''indefinitely suspended'' serving uncooked tomatoes.
The U.S. Food and Drug Administration is investigating the source of the outbreak, agency spokeswoman Kimberly Rawlings said. ''We are working hard and fast on this one and hope to have something as quickly as possible,'' Rawlings said Monday.
Cherry tomatoes, grape tomatoes, tomatoes sold with the vine still attached and homegrown tomatoes are likely not the source of the outbreak, federal officials said.
Also not associated with the outbreak are raw red Roma, red plum and round red tomatoes from Belgium, Canada, the Dominican Republic, Guatemala, Israel, the Netherlands and Puerto Rico.
The Centers for Disease Control and Prevention has said that since mid-April, 167 people infected with salmonella with the same ''genetic fingerprint'' have been identified. At least 23 people have been hospitalized.
A 67-year-old cancer patient in Texas who health officials said was sickened by salmonella at a Mexican restaurant is believed to be the first death associated with the outbreak.
Salmonella is a bacteria that lives in the intestinal tracts of humans and other animals. The bacteria are usually transmitted to humans by eating foods contaminated with animal feces.
Most infected people suffer fever, diarrhea and abdominal cramps starting 12 to 72 hours after infection. The illness tends to last four to seven days.