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Cornell University researchers have created an atlas made up of 1,854 Listeria isolates gathered from soil samples across the United States.
The study, published in the July issue of Nature Microbiology, analyzed soils samples from several different locations across the country, and discovered that the bacterium was “present across a wide range of environmental parameters, being mainly controlled by soil moisture, molybdenum and salinity concentrations.”
One goal of the study was to make it easier to detect Listeria monocytogenes in food recalls and other similar scenarios. Senior author Martin Wiedmann gave an example of a use for this atlas: if Listeria is found in a processing facility in one state that used ingredients from another state, those ingredients could be checked against the soil samples from the source state of the various ingredients.
“You can use this information almost like a traceback,” he said. “It’s not always proof, but it leads you to evidence.”
Understanding Listeria
Listeria monocytogenes is a common cause of food-borne illness outbreaks. The illness from the bacterium, referred to as listeriosis, can be tough to diagnose because it’s so similar to other kinds of sickness.
Some symptoms can present in as little as one day, and other times, these symptoms only begin to appear between two to 30 days after contracting the illness.
Most people experience these symptoms:
- tiredness
- aches and pains
- fever
- headache
A few experience these rarer signs of Listeria:
- abdominal cramps
- nausea
- diarrhea
Listeria can be found in foods like cold meat, cold cooked chicken, chilled seafood, soft cheese, unpasteurized dairy products, soft serve ice-cream and pre-packaged salad. It’s highly resistant and can survive at temperatures other bacteria would die or stop reproducing.
Prevention starts with cleanliness
Effective cleaning and sanitizing is the best way to prevent contracting Listeria or spreading it in your workplace. Because it can survive on surfaces, thorough cleaning of countertops and all equipment is recommended, using detergent to break up the biofilm that Listeria bacteria survive in.
Research such as this genomic and geological mapping tool may make it easier in the future to be able to track down the origin of Listeria isolates. Understanding how often various Listeria are found in different places will help to prevent contamination from entering the food chain through a backtracking process to determine the source of an outbreak.
