E. coli bacteria swim through bodies of water, then swim through bodies of people, possibly making them sick.

Researchers at the University of Illinois at Urbana-Champaign now know more about how those bacteria swim around thanks to a new invention that involves trapping the microscopic critters and watching them move.

In essence, the researchers use lasers to guide the bacteria onto what they call miniscule treadmills. The lasers control but don't impede the movement of the bacteria.

The scientists hope to then use chemicals to change the environment surrounding the bacteria to replicate the composition of a lake, a sewer or a human stomach to see how the microbes respond and whether they change direction.

The presence of E. coli in food or water indicates the presence of animal or human feces. Testing is done to make sure the bacteria stays at levels that people can tolerate without getting sick.

E. coli has been in the news recently with reports that high levels of the bacteria were found in the Lake of the Ozarks in May.

Most E. coli infections are caused by the 0157:H7 strain of the bacteria. People with compromised immune systems, including the youngest and oldest in the population, are at a higher risk of developing symptoms that typically include stomach cramps and diarrhea. Serious cases can lead to kidney damage.

Previously, researchers have been able to track the movements of the bacteria in their environment for only about 30 seconds. The new method out of Illinois can monitor movements for an hour.

Physics professors Yann Chemla and Ido Golding led the study, which serves as a new window into bacteria behavior.

"It's a basic understanding of the way living cells respond to their environment," Golding said.

The way the bacteria move is directly related to their infectious qualities, he added. The physicists' invention may also be used in studying other bacteria besides E. coli.

"Characterizing their swimming behavior in a high quality way does have high potential for also improving the understanding of harmful aspects of their behavior."

The researchers' work was recently published in the journal Nature Methods.