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article imageCheaper and faster test for E. coli in drinking water

By Tim Sandle     Sep 7, 2017 in Science
Waterloo - Access to clean drinking water is a basic human right. In some parts of the world water is contaminated, especially from agricultural run-offs. To ensure water is free from one notorious pathogen, a low-cost rapid test method has been developed.
Scientists from the University of Waterloo have developed the rapid and affordable method to test their drinking water for potentially deadly bacterium Escherichia coli. The technology is aimed at the developing world, since access to clean water is more challenging. However, the researchers were also inspired by an incident closer to home: E. coli was the cause of a serious infection outbreak in Walkerton, Ontario in 2000.
Based on the success, the researchers have founded a start-up company to commercialize the product. The company is called Glacierclean Technologies Inc. The technology provides a useful example of what a startup company, coming from the university sector, can achieve.
The new test costs less than 50 cents to run. This compares with other screening tests which cost upward of $70 to run. Moreover, conventional tests based on bacterial culture take three days to produce a result. The new development uses a simple strip of paper, much like established litmus paper, which is used to assess the acidity of a liquid rapidly. According to the lead researcher, Dr. Sushanta Mitra, who works at the Waterloo Institute for Nanotechnology: "This has the potential to allow routine, affordable water testing to help billions of people in the developing world avoid getting sick. It is a breakthrough.”
Some strains of E. coli can cause disease in humans. Virulent strains can cause gastroenteritis, urinary tract infections, neonatal meningitis, hemorrhagic colitis, and Crohn's disease. Patient symptoms include abdominal cramps, diarrhea, hemorrhagic colitis, vomiting, and sometimes fever. The main route of infection is via fecal contamination of food and water supplies. It is the link to drinking water that the new technology is concerned with.
The testing is not only concerned with the detection of E. coli, it allows for the screening of other potentially harmful bacteria. Where fecal contamination of water has occurred, E. coli is normally present making it an candidate indicator organism.
The test works since the bottom of the paper strip is laced with sugar. The sugar begins to dissolve when placed in water. E. coli bacteria are then attracted by the resulting sugar trail (a chemoattractant) and become trapped in the porous paper. As water enters the paper, it transfers the trapped bacteria into an area of the strip containing a mixture of chemicals. The bacteria then react with the chemicals and turn the strip pinkish red, which indicates a positive test for E. coli. This informs the user that the water is unsuitable for drinking. The performance of the DipTest device was checked with different known concentrations of E. coli contaminated water samples using different dip and wait times.
The technology has been presented to the journal PLOS One in a paper headed "DipTest: A litmus test for E. coli detection in water."
More about Water, Bacteria, E coli, Infection
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