Ask the Doctors

Dear Doctor: Like practically everyone else in the United States, we threw out our romaine lettuce because of the E. coli outbreak. What is E. coli and how do we avoid it?

Dear Reader: E. coli is a type of bacteria that lives in the intestines of humans and some animals. It exits the body in feces and can survive outside of the intestines for several hours. Most strains of E. coli (Escherichia coli, for our fellow science nerds) are harmless. In fact, they're a natural part of our gut microbiome. The "good" E. coli perform helpful functions, like the synthesis of certain vitamins and keeping certain pathogens from colonizing the colon.

However, a few strains of E. coli cause disease, including gastroenteritis, which is what we're seeing with the present outbreak. And the potential dangers of the "bad" versions of E. coli don't end there. Pathogenic strains can cause illnesses outside of the gastrointestinal tract, including respiratory illness, pneumonia, urinary tract infections and neonatal meningitis.

When it comes to the current outbreak, laboratory tests show that the strain involved, identified as E. coli O157:H7, produces a particularly nasty toxin; in fact, the hospitalization rate has been higher than in previous outbreaks. As you noted in your question, this outbreak centers around romaine lettuce, which has been contaminated with fecal material containing the pathogenic E. coli.

Infection with E. coli begins anywhere from two to five days after exposure. The first symptoms are abdominal pain, cramping and tenderness, which within 24 hours are followed by diarrhea. As the infection progresses, the diarrhea becomes increasingly watery and -- this can be the scary part -- visibly bloody. That's because the toxin in this particular strain damages the lining of the small intestine. Nausea and headache may accompany the diarrhea, and some people may experience chills and fever. The disease typically runs its course in a week or so. However, in some vulnerable populations, such as young children, older adults and those with weakened immune systems, something called hemolytic uremic syndrome, which is a type of kidney failure, can occur.

The federal Centers for Disease Control and Prevention has warned consumers against romaine lettuce grown in the Yuma, Arizona, region. Unless you know specifically where the romaine lettuce in your fridge originated, it is safest to throw it away. This includes whole heads, hearts, pre-packaged lettuce mixes and premade salads. These same precautions apply to romaine served in restaurant.

In general, the best precaution against infection with E. coli is good hand hygiene. Always wash hands after using the bathroom, changing a diaper or helping someone else use the toilet. Wash hands before handling and preparing food, and after contact with animals.

Always wash fruit and vegetables thoroughly under running water; cook meats to their recommended internal temperatures; and be careful about cross-contamination in the kitchen. Anything that has come into contact with raw meat -- whether it's your hands, countertops, knives, cutting boards or utensils -- is a potential source of disease-causing E. coli.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

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