A new approach, reported online Oct. 14 in the journal Applied and Environmental Microbiology by a collaborative team led by Cornell University scientists, will enable government agencies and food companies to pinpoint the exact nature and origin of food-borne bacteria with unprecedented accuracy, says food science professor Martin Wiedmann.
The standard method of tracing food-borne illness involves breaking up the DNA of bacteria samples into smaller pieces and analyzing their banding patterns.
But scientists often find that different strains of bacteria have common DNA fingerprints that are too genetically similar to be able to differentiate between them, making it difficult to establish whether the salmonella that made one person sick was the same salmonella that infected another person. This was the case in a salmonella outbreak linked to salami made with contaminated black and red pepper that included 272 cases in 44 states between July 2009 and April 2010.
To surmount this challenge, Wiedmann adopted a genomic approach.
By sequencing the genome of 47 samples of the bacteria -- 20 that had been collected from human sources during the outbreak, and 27 control samples collected from human, food, animal and environmental sources before the outbreak -- Wiedmann and his team were able to rapidly discriminate between outbreak-related cases and non-outbreak related cases, isolating four samples believed to be connected to the pepper contamination.
In the process of doing so, he also found other links: A Salmonella strain that led to a nationwide recall of pistachio nuts in 2009 turned up in samples from four people -- only one of whom had reported eating pistachios.
Other connected cases suggested smaller outbreaks of which officials had been previously unaware.
"The use of genome sequencing methods to investigate outbreaks of food-borne bacterial diseases is relatively new, and holds great promise as it can help to identify the temporal, geographical and evolutionary origin of an outbreak," Wiedmann said. "In particular, full genome sequence data may help to identify small outbreaks that may not be easily detected with lower resolution subtyping approaches."
Wiedmann, research associate Henk den Bakker and other lab members developed the single nucleotide polymorphism (SNP) test that is specific to the 2009 pepper-associated outbreak with the help of researchers at Life Technologies Corp. They also collaborated with researchers at Washington State University and departments of health in New York City and New York state.
A similar approach has previously been used in hospital settings to trace pathogenic bacteria such as methicillin-resistant Staphylococcus aureus, but this is its first application for food-borne illness.
Wiedmann said he is continuing to perfect the method and use it to test other types of bacteria. The U.S. Food and Drug Administration and other agencies are also starting to use similar approaches.
Joe Schwartz | Newswise Science News
Satellites, airport visibility readings shed light on troops' exposure to air pollution
09.12.2016 | Veterans Affairs Research Communications
Oxygen can wake up dormant bacteria for antibiotic attacks
08.12.2016 | Penn State
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine