18 Apr 2023 --- Researchers at McMaster University, Canada, have developed a test for Salmonella contamination that “provides accurate results in an hour or less.” The inexpensive test could improve food safety and mitigate broad recalls of contaminated food.
Salmonella is one of the primary contamination risks for poultry processors, with major chicken producers having to perform “tens of thousands” of lab tests each year to prevent the infection, which causes 155,000 deaths each year globally, according to the report.
The report notes that: “The Centers for Disease Control and Prevention (CDC) reports an estimated 450 deaths, 23,000 hospitalizations and US$365 million in direct medical costs are caused by Salmonella infection alone in the US each year.”
Reducing or eliminating the need for overnight Salmonella testing and replacing it with a rapid, easily-used test will save time and money, notes study co-author Yingfu Li, a Biochemistry and Chemical Biology professor and leader of McMaster’s Functional Nucleic Acids Research Group.
“Anyone can use it right in the setting where food is being prepared, processed or sold,” he says.
“There’s a balance between cost, convenience and need. If it’s cheap, reliable and easy, why not use it?”
“Easier than using a COVID test”
The research team focused on making the test as rapid and easy to use as possible.
“Using these tests is easier than using a COVID test, which so many people are already doing,” highlights co-author Carlos Filipe, chair of McMaster’s Department of Chemical Engineering.
“For this to be as effective and useful as possible, it has to be easy to use.”
The test itself is based on a new synthetic nucleic acid molecule, which was developed at McMaster. This molecule is sandwiched between microscopic particles lining the tip of a pipette.
When a liquefied sample of the food being tested is drawn inside the tube, Salmonella bacteria, if present, will cut through the microscopic particles, allowing the acid molecule to escape.
When dripped onto test paper, the resulting solution will turn a visible shade of red. The higher the concentration of Salmonella, the brighter the red will be.
“Creating a test that is both easy to use and which produces a readily visible color within an hour is significant,” adds co-author Tohid Didar, an associate professor of Mechanical Engineering and Canada Research Chair in Nano-biomaterials.
The report, A Simple Colorimetric Au-on-Au Tip Sensor with a New Functional Nucleic Acid Probe for Food-borne Pathogen Salmonella typhimurium was published in the journal Angewandte Chemie, and further notes that the rapid test could also ensure the safe processing of other foods particularly vulnerable to Salmonella, such as eggs, dairy and beef.
Food safety in spotlight
EU regulators warned last December of an overall increase in reported cases of zoonotic diseases and foodborne outbreaks compared to the previous year, adding that levels are still “well below” those of the pre-pandemic years.
These findings were revealed in the latest annual EU One Health zoonoses report, which flagged that most foodborne outbreaks (773) were caused by Salmonella, which accounted for 19.3% of the total.
Last year, the European Food Safety Authority called for “prudence in the use of antimicrobials in all sectors, including agriculture,” following findings that antimicrobial resistance (AMR) remains high in some strains of Salmonella. However, it noted a recent improvement in strain vulnerability to antibiotics.
