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
New malaria analysis method reveals disease severity in minutes
14.08.2017 | University of British Columbia
New type of blood cells work as indicators of autoimmunity
14.08.2017 | Instituto de Medicina Molecular
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Information Technology