Employing advanced genetic-tracing techniques and sharing the data produced in real time could limit the spread of bacteria – Bacillus cereus – which causes foodborne illness, according to researchers. As part of a recent study, researchers at Penn State University implemented whole-genome sequencing of a pathogen-outbreak investigation, following an outbreak of foodborne illnesses in New York in 2016.
“Here, in our study, we use this approach for the first time on Bacillus cereus,” says Jasna Kovac, assistant professor of Food Science at Penn State. “We hope that whole-genome sequencing of Bacillus will be done more often as a result of our research, as it allows us to differentiate between the various species of Bacillus cereus group and project the food-safety risk associated with them.”
The project marks the first time researchers have conducted whole-genome sequencing to investigate a Bacillus cereus outbreak to link isolates from human clinical cases to food. The New York outbreak in 2016 lasted less than a month and stemmed from contaminated refried beans served by a small Mexican restaurant chain.
Although the toxin-producing bacteria are estimated to cause 63,400 foodborne disease cases per year in the US, Bacillus cereus does not receive the attention given to more deadly foodborne pathogens such as Listeria and Salmonella.
Because illness caused by Bacillus cereus typically resolves within days and outbreaks are self-limiting in nature, foodborne illness caused by members of this pathogen group are often under-reported. Although there have been reports of severe infections resulting in sudden patient death, Bacillus cereus group isolates linked to human clinical cases of foodborne disease typically do not undergo whole-genome sequencing, as is becoming the norm for other foodborne pathogens.
In this case, the New York State Department of Health coordinated the epidemiological investigations. The methods included a cohort study, food-preparation review, a food-product traceback, testing of the environment, food and water and an inquiry at a production plant in Pennsylvania that produced the contaminated refried beans. The researchers sequenced the majority of Bacillus cereus isolates, from both food and humans, at the Penn State Genomic Core Facility, which is part of the Huck Institutes of the Life Sciences.