The CDC has not been able to identify a common grower, supplier, distributor or brand of romaine lettuce.
The latest multistate outbreak of E. coli has sickened 35 people, including seven in New Jersey and nine in Pennsylvania.
The CDC reported that the infection has been found in 11 states.
Consumers who purchased romaine lettuce at a grocery store or eat the same at any restaurant should confirm that it is not the chopped romaine lettuce from the Yuma, Arizona growing region.
Some local grocers, such as Albertsons and Safeway, removed bagged salads and deli items containing romaine lettuce from stores, Albertsons communications and community relations manager Kathy Holland wrote in an email.
CDC also said the number of cases may increase "due to the time it takes between when a person becomes ill with E. coli and when the illness is reported".
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The Center for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) recommended that people not eat bagged and chopped romaine lettuce after a possible E. coli contamination. Most will get better within a week, but the symptoms can last longer and be severe. The majority of E. Coli cases 69 percent occurred in women, although people of both genders ages 12 to 84 years have been affected by the outbreak.
Restaurants and retailers have been advised not to sell or serve any chopped romaine lettuce and consumers are told to throw away any store-bought lettuce or salad mixes immediately, according to the Montana Department of Health and Human Services.
Twenty-two of them have been hospitalized, including three with kidney failure. The CDC advises anyone with these symptoms to seek medical attention as E. coli infection is typically diagnosed via a stool sample.
Information collected to date indicates that chopped romaine lettuce from the Yuma, Arizona growing region could be contaminated with E. coli O157:H7 and could make people sick.
Phillips said anyone who thinks they've eaten contaminated romaine and are experiencing "diarrhea and nausea and sometimes a fever, but generally a very low fever and it can actually turn into bloody diarrhea", should head to the doctor.