Over 53 people have been reported ill in 16 states since March 13, the CDC said. Thirty-one of these patients were hospitalized. Five of them developed a type of kidney failure that is associated with an E. coli disease called hemolytic uremic syndrome, which can be life-threatening.
No deaths were reported, according to the CDC.
The higher numbers of E. coli cases have been in Pennsylvania, Idaho, New Jersey and Montana.
The outbreak has also reached consumers in Alaska, Arizona, California, Connecticut, Illinois, Louisiana, Michigan, Missouri, New York, Ohio, Virginia and Washington.
The symptoms of E. coli typically begin two to eight days after eating the bacteria, although most patients get sick three or four days after consumption. Symptoms include severe stomach cramps, diarrhea and vomiting. Most people recover in five to seven days. The most vulnerable E. coli diseases include the very young, the very old and the weakened immune system.
Health officials had issued a warning to local residents and restaurants about chopped romaine lettuce, which is most recently grown in the area of Yuma, Arizona, week
"Most people reported eating a salad in a restaurant, and romaine lettuce was the only common ingredient among the salads that were eaten, "the CDC said in a statement.
"Restaurants reported using bagged, chopped romaine lettuce to make salads not from whole heads or hearts of Romans, "says the center
The agency recommends that people in the United States stay away from minced romaine lettuce.
"Consumers everywhere in the United States who have bought home-baked romaine lettuce, including lettuce, s and salad mixes, should not eat it and should throw it away, even if some of it was eaten and nobody got sick Do not know if the salad is Romaine, do not eat it and throw it away, "said the CDC.
CNN's Joe Sutton and Debra Goldschmidt have contributed to this report.