Researchers at the University of Waterloo and York University have come up with a cheaper and faster method for detecting the presence of deadly E. coli bacteria in drinking water through a simple litmus dip test.
The new approach could have a widespread impact on health in developing countries as well as anywhere a quick and accurate measure of water contamination is needed, say the authors.
Bio-sensing research is proceeding by leaps and bounds, thanks to nanotechnology and the creation of paper-based biosensors for detecting a number of substances, from testing blood samples for infectious diseases to tests for grains in agriculture and chemical contaminants in both water and soil. And while devices for isolating bacteria in water already exist, none are dedicated to registering E. coli contamination nor are they as fast and cheap as the new invention.
Typical E. coli tests can cost about $70 and involve lab work, meaning that detection can take up to three days to complete. The new method uses a strip of blotting paper coated with a glucose solution to attract the bacteria along with specially formulated chemical reagents that turn the strip a pinkish red when in contact with E. coli. The process takes just 30 minutes for detection in water with high levels of contaminant and 180 minutes for lower levels, all for just 50 cents per test.
“This has the potential to allow routine, affordable water testing to help billions of people in the developing world avoid getting sick,” said Sushanta Mitra, executive director of the Waterloo Institute for Nanotechnology and study co-author in a press release. “It is a breakthrough.”
While E. coli (Escherichia coli) bacteria are common inhabitants in human and animal intestinal tracts, a small number of strains, such as E. coli O157:H7 can produce infections with health consequences ranging from diarrhea and stomach cramping to life-threatening kidney failure.
E. coli can be present in water but also in foods like raw vegetables, unpasteurized milk and meats like beef, chicken, turkey and ham. The bacteria was first detected in 1982 in connection with an outbreak of severe, bloody diarrhea in the United States that was traced to tainted hamburger meat (giving E. coli its moniker, the “hamburger disease”).
In May of 2000 in Walkerton, Ontario, an E. coli outbreak occurred when the bacteria contaminated the town’s water supply, resulting in seven deaths and more than 2,300 cases of sickness. The outbreak was traced to manure spread on a farmer’s field near one of the town’s wells.
Natural disasters can bring about E. coli contamination, as well. Health experts in Texas and Louisiana have reported elevated levels of coliform bacteria and E. coli in the wake of Hurricane Harvey, which caused severe flooding along the Gulf Coast.
As the new litmus test allows for point of source water screening, Mitra expects it to have a real impact.
“Simple ideas create paradigm shifts in technology and this is a simple, frugal innovation,” said Mitra.
The research is published in the journal PLoS ONE.