September 16, 2017
1 min read

New, low-cost test detects E. coli in water

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Researchers have developed a simple and inexpensive test that can be used to detect Escherichia coli in drinking water.

Although it can take up to 3 days to receive laboratory results with current tests, which typically cost around $70, the DipTest device can produce results in less than 3 hours at a cost of 50 cents per test strip, according to a press release.

“This has the potential to allow routine, affordable water testing to help billions of people in the developing world avoid getting sick,” Sushanta Mitra, PhD, executive director of the Waterloo Institute for Nanotechnology, said in the release. “It is a breakthrough.”

The test is based on a novel paper strip similar to litmus paper. The bottom of the strip is laced with sugar, which dissolves when placed in water. The sugar trail attracts any E. coli bacteria present in the water to the paper. The bacteria are then trapped in the paper and transmitted to a “reaction zone,” where chemicals turn the strip to a pinkish-red color, indicating a positive result.

Mitra and colleagues assessed the accuracy of the test using various concentrations of E. coli-contaminated water samples. It took less than 30 minutes to produce results when testing water with higher levels of E. coli and up to 180 minutes when testing water with lower levels of contamination, according to the release. The amount of time the device took to detect E. coli decreased when the test strip was soaked in water for a longer duration. Results were not affected by chemical contaminants that were deliberately added to some of the samples.

The researchers said the test strips may be used to check the quality of water in swimming pools, lakes, rivers and beaches. Glacierclean Technologies Inc., a company cofounded by Mitra, is refining the DipTest and plans on having the device available on the market within 9 months, the release said.

“Simple ideas create paradigm shifts in technology, and this is a simple, frugal innovation,” Mitra, who also is a mechanical and mechatronics engineering professor at Waterloo, said. – by Stephanie Viguers

Disclosures: The authors report no relevant financial disclosures.