From romaine lettuce to frozen falafel, the U.S. Food and Drug Administration (FDA) recall list is filled every year with items contaminated with Escherichia coli (E. coli) that cause multiple foodborne illnesses. E. coli is the bacterial culprit behind an estimated 265,000 annual infections in the United States, according to the Centers for Disease Control and Prevention (CDC). Now, a spray that researchers describe as billions of tiny soldiers offers a new way to disinfect food and reduce outbreaks.
At McMaster University, professor Zeinab Hosseinidoust, professor Tohid Didar and graduate student Lei Tian developed a way to fight foodborne illnesses by using bacteriophages. A bacteriophage, also called a phage, is a type of virus that cannot infect human cells. However, the bacteriophage name reveals its useful purpose: It is a bacteria eater that can infect and destroy bacteria.
Bacteriophages infecting bacteria, illustration.
In their paper, published in Nature Communications, the researchers describe linking the bacteriophages together to create microscopic beads, with each bead about 20 microns in diameter. For comparison, a human hair is about 70 microns in diameter. All together, they linked half a million bacteriophages to make each bead and constructed a community of 13 billion bacteriophages.
Once assembled, the highly organized bacteriophages were sprayed on romaine lettuce and beef steaks contaminated with E. coli O157:H7, a strain of the bacteria that causes severe intestinal infections and often infects lettuce and meat. Then, the army of tiny bacteriophage soldiers went to work.
The researchers reported the results by sharing the log reductions, which show how effective the spray was in killing the bacteria. The bacteriophage spray reduced the E. coli O157:H7 by 6 logs or 99.9999%.
In addition to being highly effective, the bacteriophage spray is safe to use on food and does not change the taste, texture or quality of the food. Moreover, bacteriophages are specific and only harm the target bacteria while leaving beneficial bacteria alone.
Antimicrobial resistance is on the rise, but bacteriophage disinfectants show promise and the possibility of filling the gaps that ineffective antibiotics create. It is important to note that since 1958 the FDA has recognized bacteriophages and their derivatives as GRAS (generally recognized as safe). Bacteriophages are already being used in products ranging from animal feed to pet food.
The researchers see many potential uses for a bacteriophage spray. First, it can be modified to destroy other types of bacteria, including Salmonella and Listeria, that frequently contaminate food. Second, it can be used in commercial applications for food harvesting, processing and packaging. Third, grocery stores can spray produce on store shelves with bacteriophages in addition to water. Fourth, bacteriophages can be added to household disinfectant products that can decontaminate everything from fresh lettuce to fruits.
Finding new ways to decontaminate food is essential for preventing illnesses. The World Health Organization (WHO) estimates 600 million people become sick after eating contaminated food, and 420,000 people die every year. Children under the age of five account for almost one-third of all illnesses, with 125,000 dying every year. Bacteriophages have the potential to reduce global foodborne diseases and save lives.