Summary: A biogel-based test uses bacteriophages to detect harmful bacteria in fluids quickly, accurately, and without the need for lab equipment.
Takeaways:
- Innovative Technology: The test uses bacteriophages in a biogel to locate and attack bacteria, causing a visible color change, enabling users to confirm contamination in fluids such as milk, urine, or lake water.
- Fast and Accurate Results: This hands-free test delivers results in hours, significantly faster than traditional lab cultures that can take up to two days, with confirmed accuracy in detecting pathogens like E. coli and listeria.
- Broad Applications: The test can be adapted to detect various bacteria, offering a simple, portable solution for food safety, environmental monitoring, and at-home medical diagnostics.
A new novel test for bacteria in fluids makes it easier to confirm the presence of disease-causing pathogens, promising much easier diagnostic tests and greater food safety.
Engineers and biochemists at McMaster university brought their skills together to make it possible for untrained users to confirm contamination in fluids using a biogel test that changes color in the presence of such bacteria as E. coli, listeria, and other frequent testing targets.
Analyzing Bacteriophages for Bacteria Detection
The test uses harmless bacteriophages embedded in the gel to locate target bacteria in a sample of fluid such as lake water, urine or a container of milk, even in low concentrations.
Bacteriophages are the most common form of life on Earth. Each form of bacteriophage is specialized to destroy one form of bacteria.
In the test, phages—as they are called informally—find and attack the target bacteria in a sample, causing the bacteria to release microscopic amounts of intracellular material which the test can read, triggering a color change that is readily visible to the eye. If the sample is clean, the color stays the same.
The new process takes just hours, producing results much more quickly than lab cultures, which can take two days to generate results.
“We’ve been using phages’ destructive power to kill bacteria and resolve infections for years,” says Zeinab Hosseinidoust, an associate professor of biomedial and chemical engineering who holds the Canada Research Chair in Bacteriophage Bioengineering. “Here, we’re chanelling that power in another way. Because phages can burst bacteria open, they can give us quick access to the biological components of those bacteria that we use to confirm their presence.”
A Lab-Free Testing Solution
The test, described in a new paper published in the journal Advanced Materials, is the latest in a series of technologies the group has developed, all aimed at placing simple technology within reach of producers, retailers, consumers, and medical professionals.
“Now we have a tool that can be used in food samples, environmental samples and clinical samples,” says corresponding author Tohid Didar, an associate professor of mechanical and biomedical engineering who holds the Canada Research Chair in Nano-Biomaterials. “Today, people who suspect they may have a urinary-tract infection must visit a doctor and sometimes wait days for a result. This technology would make it very easy for people to tests themselves at home and get a result in a matter of hours.”
The group’s previous work includes creating a portable testing library to match phages to otherwise untreatable antibiotic-resistant infections, a contamination test incorporated into food packaging, and a temperature-stable storage system for live vaccines.
The group confirmed the concept of their newest test using urine samples from patients at Hamilton Health Sciences, and in all cases, results from the experimental test produced the same results as traditional lab tests. The test also worked accurately to detect E. Coli in lake water samples.
Further Reading
The new test can be adapted to any bacterium by using bacteriophages and DNA probes that specifically target microbes such as listeria and salmonella.
“Phages can knock on every biological door, but they will only enter the ones they are programmed to find,” says Carlos Filipe, a professor of chemical engineering and a senior author on the paper. “That specificity is a huge advantage for quick and precise detection, even at low levels.”
Such a test could have provided early and accurate detection in the recent listeria contamination of plant-based milk that killed two, sickened 10 and caused wide recalls in Canada, the researchers say.
“This technology could be helpful in rapidly limiting outbreaks,” says co-author Akansha Prasad, a Vanier Scholar and PhD student in biomedical engineering. “If you had something in your fridge that you were concerned about, this test could let you know if it was safe for consumption.”
Testing for contamination in complex fluids such as milk, blood or urine is especially challenging, making simple, reliable alternatives such as the new test very useful, say the researchers, who hope to work with commercial partners to bring the technology to the marketplace.
“Once we have the appropriate approvals and partnerships to move this test to market, it could be very useful in many settings,” says the paper’s lead author Hannah Mann, a PhD student in chemical engineering and bioengineering. “About 12 per cent of Canadians don’t have access to municipal piped water, for example, and this could bring them a lot of peace of mind.”
The paper’s other authors are Yingfu Li, Shadman Khan, Feresheteh Bayat, Jimmy Gu and Kyle Jackson.
Featured image: A new test developed by researchers at McMaster University uses a novel technology to find bacteria in liquids and indicate their presence by changing color. Photo: Georgia Kirkos/McMaster University
