Researchers find new types of E. coli

March 10, 2008 12:00:00 AM PDT
A new analysis of E. coli bacteria reveals there are different sub-types of it, and the most dangerous form is actually becoming much more common in food borne outbreaks. Fortunately, there is some new technology that can help detect it more quickly.

Believe it or not, E. coli is usually a harmless bacteria present in the human digestive systems, but one strain of it, known as E. coli 0157, is one our bodies have trouble stopping.

In 2006, a contaminated spinach field in the Salinas Valley led to a nationwide E. coli outbreak, killing three people and sickening hundreds more. While investigators scrambled to find the source and contain it, fresh spinach was pulled from store shelves across the country. Food toxicologists noted this outbreak continued a recent pattern of doing more harm to its victims.

"The disease has gotten much worse than it was, with a much greater fraction of people having to go to hospital and a much greater fraction of people that are seriously infected with the toxin," says Thomas Whittam PhD. of Michigan State University.

Genetic testing led by Whittam found there are multiple sub-types of the strain of E. coli bacteria that makes people ill.

"We've been able to identify eight different groups and this group eight seems to be the most serious," says Whittam.

And Whittam's genetic tracking shows this more dangerous type is appearing 50 percent more often than just two years ago. Whittam says he's not yet sure why the bacteria has become more of a threat.

"It's either added some of its ability to rapidly spread into human sources, or it's acquired something that causes it to be more serious once it infects humans."

Whittam and his team were able to run their tests in just a few days -- tests that previously took months. It's technology that could make a big difference in identifying the source of an outbreak quickly.

So far, his genetic tests have concentrated only on samples from victims. Whittam wants to expand testing to our food sources to better understand how it's getting into our food supply. The research was funded by the National Institutes of Health and is published online in the proceedings of the National Academy of Science.