The E.coli outbreak linked to romaine lettuce remains unstoppable. It has now sickened 28 more people and affected four more states, confirms the Centers for Disease Control and Prevention.

There are now 149 cases of persons falling ill after consuming romaine lettuce, with a total of 29 states affected. The bacteria recently killed one person in California, marking the first fatality tied to the outbreak. Of the 164 cases, 64 — or 50 percent — involve hospitalizations, with 17 developing hemolytic uremic syndrome, a form of kidney failure that could be life-threatening. No additional deaths have been reported.

E. Coli Romaine Lettuce Worsens

The problem stems from bacteria-tainted romaine lettuce grown near Yuma, Arizona. It is the largest multi-state E. coli outbreak in 12 years.

"Of the 112 people interviewed, 102, or 91%, reported eating romaine lettuce in the week before their illness started," the CDC announced on its website May 9. "This percentage is significantly higher than results from a survey of healthy people, in which 46% reported eating romaine lettuce in the week before they were interviewed."

Cases could still increase, since the time that passes between when a person getting sick and when it's reported takes an average of two to three weeks, according to the CDC. By the end of May, it's possible that more cases will be recorded.

E. Coli Symptoms

Symptoms of E. coli typically begin three to four days after the bacteria is ingested. These include stomach cramps, diarrhea, and vomiting. With supportive treatment, most people recover in a matter of five to seven days.

Don't Use Antibiotics

The CDC has cautioned against the use of antibiotics to treat the illness because studies have linked antibiotic use with an increased risk for hemolytic uremic syndrome in both children and adults.

"Antibiotics are not recommended for patients with suspected E. coli O157 infections until diagnostic testing can be performed and E. coli O157 infection is ruled out," the CDC says.

The U.S. Food and Drug Administration says it has received confirmation from the Arizona Department of Agriculture that romaine lettuce is no longer being produced or shipped from the Yuma area.

Products containing romaine lettuce often don't indicate growing regions, so it could be difficult for consumers to tell whether the vegetable they're buying is tainted with bacteria. For now, the CDC says people shouldn't buy romaine lettuce unless they can be sure where it was grown.