Australian researchers are analyzing bacteria strains in a new way that may make it easier to determine different foodborne illness outbreaks. The findings, which were published in the Journal of Bacteriology, track outbreaks  through a DNA test that was observed at the University of Melbourne, Australia.

Researchers were able to identify if food poisonings, such as the common Salmonella Typhimurium, were isolated incidences or if they were larger outbreaks. The test, Multiples Locus Variable-number Tandem Repeat Analysis (MLVA) is a technique used to generate a DNA fingerprint of a specific bacterium. It’s another way of figuring out what may have caused the outbreak, without having to retrace the steps of who ate what and where. Researchers can look inside the DNA using MLVA and find out how many times it has reproduced by looking at clusters of DNA instead of just single strains.

"This tells us we don't need to worry about where the bacteria were isolated from—humans or food," the study’s co-author Kathryn Holt, said.

Foodborne illnesses, also known as food poisoning, are infections of the gastrointestinal (GI) tract, which are oftentimes painful and unsettling, and caused by a harmful bacteria, parasite, virus, or chemical. It’s exposed to the human body through a food or beverage, and although they usually last a short time they’re something to try and seriously avoid.

According to the National Institutes of Health, 48 million Americans experience a foodborne illness each year and of those, 3,000 people die. Salmonella in particular is found in many uncooked meat, poultry, dairy products, eggs, and seafood.

The test can connect the suspected, fast-evolving bacterial strains to an outbreak and find out if they look similar to other people’s strains. Salmonella outbreaks were never investigated for the timeliness of its outbreaks until now using the MLVA test, which was also replicated in mice over a 500-day time period. They observed the same bacteria changes throughout a bacteria’s lineage, which was identified thanks to the test tracing its DNA. Also, those which replicated in clusters of two and threes were of the same outbreak. Overall using the markers as clusters will help the speed and efficacy of foodborne illness testing if it can also be replicated with other foodborne illnesses.

Another technique used to lift the bacteria’s fingerprints is the Pulsed-field Gel Electrophoresis (PFGE), which is used to separate large DNA strands and identify them. This allows scientists to discern large quantities of bacteria from one another and determine where they’re coming from and how many times they’ve replicated.

"In the U.S., the Centers for Disease Control and Prevention uses another technique called PFGE for initial investigations and follows that with MLVA," Holt said.

 

Source: Chevance FFV, Skukui G, Alshamy I, et al. Analysis of Factors That Affect FlgM-Dependent Type III Secretion for Protein Purification with Salmonella enterica Serovar Typhimurium. Journal of Bacteriology. 2014.