Researchers Find Faster Method to Detect E. coli Bacteria

Newswise -- Researchers at the University of South Florida have found a better, faster method to detect Escherichia coli (E. coli) bacteria, the biological hazard that can lurk in food or water and cause serious human illness and death.

Current detection methods requiring cultures can take from 24 to 48 hours to confirm the presence of E. coli. However, the method developed at USF, as explained in the October 2003 issue of The Journal of Microbiological Methods (Vol. 55, No.1), uses a combination of fiber optic biosensors and antibodies to initially detect E. coli in food or water, followed by recovery of live bacteria and confirmatory identification of their DNA sequence with the polymerase chain reaction (PCR). The new combination method can test for E coli in 10 hours.

"Rapid detection and identification can prevent food-borne and waterborne illness and allow physicians to begin treatment sooner for those thought to be suffering from E. coli contact," says Daniel Lim, PhD, professor of biology. "At the same time, rapidly reported negative test results will also prevent costly food recalls."

In the past, Lim and his team of researchers have used rapid fiber optic biosensors alone to identify E .coli in ground beef and apple cider and have been able to run tests successfully in 30 minutes. The recovery of live bacteria from biosensor tests not only permits follow-up PCR testing of a complex sample, but also provides a live sample to confirm that the bacteria are alive, allowing for other tests on the bacteria, such as tests for antibiotic resistance.

"It's important to be able to demonstrate that the sample tested was live bacteria, not dead bacteria," comments Lim.

According to Lim, by using two rapid tests in tandem - one based on an immunological reaction and one that identifies DNA - confirmation of the specific organism is assured.

"It can all be done in one workday," explains Lim.

Source: University of South Florida

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