by Zeina Mohammed, University of Virginia

A multi-state E. coli outbreak may be linked to the McDonald’s Quarter Pounder, according to the CDC. Credit: John DiJulio, University Communications

Federal and public health officials in multiple states are investigating an outbreak of E. coli infections linked to McDonald's Quarter Pounder, according to the Centers for Disease Control and Prevention. Officials are determining which ingredient may be harboring the bacteria that caused the outbreak.

Melissa Kendall started her research program studying how E. coli and other pathogens establish infection in our gut and has been researching E. coli ever since. She is an associate professor of microbiology, immunology and cancer biology at the University of Virginia and has been with the University just over 12 years.

William Petri, UVA's Wade Hampton Front Professor of Medicine and the School of Medicine's vice chair for research, also teaches immunology.

They share their thoughts on the outbreak and how to stay safe generally.

What's important to know about E. coli?

Kendall: People generally harbor some strains of E. coli in their gut, and that's perfectly normal and can be beneficial. They can help us synthesize vitamins and absorb nutrients, but there are specific types of E coli that are pathogens and cause disease. These are not normally found in our bodies. An example is E. coli O157:H7, the cause of this outbreak that's going on right now that normally lives in the guts of ruminant animals such as cows.

What makes pathogenic E. coli different is that they make different proteins, like toxins, that make us sick. You don't need to ingest much E. coli O157:H7 to make you sick. It is very well-adapted to colonize our colons, so the food doesn't have to be highly contaminated. When it gets to our colons, E. coli O157:H7 produces proteins that allow it to bind very tightly to the border of our colon, our epithelium.

E. coli outbreaks come from things contaminated by feces. If it's spreading through beef, it may be that it wasn't properly cooked. Whereas, if it's in onions, it might be from runoff water from a farm or water contaminated with manure.

What do we know about the outbreak?

Kendall: They are investigating which ingredient, likely the hamburger meat or onions, led to the outbreak.

Petri: As of today, there are 49 known infections and there has been one death. The last onset of symptoms was Oct. 11, almost two weeks ago.

Of everyone who's had this illness, the one food item most of them had in common was the McDonald's Quarter Pounder hamburger. It's not all over the country; really in the Western U.S., half of them in Colorado. We haven't had any cases on the East Coast.

The risk of getting the infection has been reduced as McDonalds has recalled both the hamburger meat and the onions that go on that sandwich.

What happens when we ingest toxic E. coli?

Kendall: Pathogenic E. coli can colonize and attach to our colons and start making a toxin called Shiga toxin. It's the Shiga toxin that causes people to become hospitalized and causes the severe sickness and death that can come from these infections, because the Shiga toxin can be absorbed into the bloodstream. It targets and can kill cells, causing renal failure. It's usually children and older people who suffer the severe complications from pathogenic E. coli infections.

Symptoms usually start about three to five days after eating the contaminated food. It usually starts with mild diarrhea that becomes more severe.

What are ways to avoid E. coli?

Kendall: Of course, the best course of action is to be hygienic and wash your hands frequently. E. coli is frequently linked to hamburger meat, because it's ground, so bacteria on the surface of the meat will be mixed in. So, hamburger meat should be cooked thoroughly. Wash your hands after handling any kind of meat. Wash the cutting boards and knives so that you're not cross-contaminating vegetables and fruits. Really, exercise common-sense caution.

What should someone do if they suspect they have ingested contaminated food?

Kendall: If they're concerned, they should drink plenty of water because diarrhea can cause dehydration. This is a bacteria we don't typically use antibiotics to treat because antibiotics are associated with an increase in Shiga toxin production; however, supportive care may be used to limit severe infection. People should monitor their symptoms, and if their diarrhea becomes more severe or contains blood, they should seek medical attention.

Provided by University of Virginia