Preventing and Detecting Foodborne Illness Bacteria

Biochemists Develop Tools To Stop Bacterial Threats
In 2011, University of Massachusetts Amherst Biochemist Alejandro Heuck and graduate student Fabian Romano characterized a needle-like tool used by bacteria, such as Salmonella, to drill holes in mammalian cell walls. From this, the team built a model membrane system to be used for further experiments.

To build on this breakthrough, Heuck recently received a five-year, $950,000 grant from the National Institutes of Health to map the molecular structure of the tool, which will further enable study of how the molecular machine known as the Type III secretion system (T3S) pokes holes, or translocons, in cell walls of warm-blooded animals and humans to inject the toxic proteins.

This is important because once a channel is open, the bacteria pump in proteins to destroy the body’s ability to fight infection. The researchers hope this advance will help to identify new targets for developing new drugs and treatment avenues.

Last year’s breakthrough opened the door to the current work by solving “a very difficult puzzle,” Heuck said. “It took a lot of experiments to understand how these water-soluble, water-loving proteins in the T3S translocon system could suddenly transform themselves drastically enough to be able to attach to a lipid-dominated cell membrane to form this molecular syringe for attacking cells.” Armed with that knowledge, Heuck and graduate student Yu-zhou Tang plan to study of Pseudomonas bacteria, both to help fight the bacteria for cystic fibrosis patients, and because many of these pathogens are listed as bioterrorism agents by the CDC.

Organic Compounds Can Eliminate Pathogens in Animals
Researchers at the Agricultural Research Service (ARS) Food and Feed Safety Research Unit in College Station, Texas, have invented a new method that involves using chlorate (sodium or salt) and nitro compounds to significantly reduce or eliminate intestinal bacterial pathogens in animals such as piglets and calves. Chlorate and nitro compounds have proven to be effective against the foodborne pathogens Salmonella and Escherichia coli O157:H7. 

UMass Amherst biochemists are mapping the molecular structure of a needle-like tool used by deadly bacteria to drill holes in mammalian cell walls. (Illustration courtesy of UMass Amherst)

Microbiologist Robin Anderson and his colleagues demonstrated the effectiveness of a chlorate-based compound in earlier research by mixing it into water or feed and giving it to cattle. The compound, which was highly effective in reducing E. coli., has been licensed by a private company. Chlorate also reduced Salmonella in turkeys and broiler chickens.

In addition, scientists looked at using certain nitro compounds as a method to control foodborne bacteria. Salmonella or E. coli bacteria were treated with or without chlorate and with or without nitro compounds. Chlorate was found to have significant bacteria-killing activity against E. coli and Salmonella, however, chlorate has not been approved for commercial use in food animals by the USDA. When the nitro compound was added, the activity was enhanced 10- to 100-fold. Nitro compounds alone also had significant bacteria-killing activity, which was more persistent than that of chlorate. From this, the team concluded that nitro and chlorate compounds together were the best treatment, and it could offer an alternative to certain antibiotics that are commonly used to treat diarrheal infections in young animals.

New Test Can Precisely Pinpoint Food Pathogens
A new approach to pathogen detection could enable government agencies and food companies to pinpoint the exact nature and origin of food-borne bacteria with unprecedented accuracy. “The use of genome sequencing methods to investigate outbreaks of foodborne bacterial diseases is relatively new, and holds great promise as it can help to identify the temporal, geographical and evolutionary origin of an outbreak,” said food science professor Martin Wiedmann, who led a collaborative team of Cornell University scientists. From the study, reported in the journal Applied and Environmental Microbiology, the team concluded that full genome sequence data may help to identify small outbreaks that may not be easily detected with lower resolution subtyping approaches,” Wiedmann said.

The standard method of tracing foodborne 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 link. To surmount this challenge, Wiedmann adopted a genomic approach.

By sequencing the genome of 47 samples of the bacteria from prior to and during an outbreak, the team was able to rapidly discriminate between outbreak-related and non-outbreak-related cases. In doing so, they also found other links, and connected cases suggested smaller outbreaks of which officials had been previously unaware. The FDA and other agencies are also starting to use similar approaches.

Biosecurity Research Institute Is Front Line for Future Security
Although tiny in size, many pathogens are an enormous threat to the food supply, economy, and health of more than 300 million Americans. Acting as a frontline offensive on this microscopic battlefield is Kansas State University’s Biosecurity Research Institute (BRI). The 113,000-square-foot facility is equipped with 31,000 square feet of laboratories and training facilities focused on securing the nation from infectious diseases. Researchers at Kansas State, USDA, and industry are using BRI for projects focused on controlling pathogens in livestock, insects, and plants which threaten food supplies and can cause serious illness or even death in humans. Currently, BRI houses studies of:

• emerging and zoonotic infectious disease, including influenza viruses and Rift Valley fever. Research on the H1N1 virus was recently published, and upcoming projects will study H5 and H7 and focus on vaccine development.
• non-O157 Shiga toxin-producing Escherichia coli, or STEC. The project, which involves thousands of pounds of ground beef, is expected to benefit livestock production at all levels.
• wheat blast, a serious wheat fungus that accounted for 30 percent of the Brazilian wheat crop losses in 2009. Researchers are working to identify resistant varieties of wheat and develop rapid detection tools for the fungus, should it spread to other countries.
• infectious and emerging swine diseases, some of which can spread from animals to humans. Projects involve creating new diagnostic tools and vaccines.
• a vaccine for strains of the porcine reproductive and respiratory syndrome virus (PRRS). The disease causes reproductive failure and respiratory illness in swine, costing the U.S. swine industry about $700 million annually.
• safety from food-based threats such as bacteria, pathogens, and toxins for deployed American troops. Because these agents can be added intentionally or unintentionally to food, studies are working to validate rapid diagnostic protocols and equipment to detect these threats in food rations.
• controlling Rift Valley fever and blue-tongue disease, as well as other arboviruses transmitted by bloodsucking arthropods like mosquitoes, ticks and midges.
• an enhanced contaminated human remains pouch (ECHRP), through funding from the Defense Threat Reduction Agency. This novel pouch is intended to be a self-decontaminating, odor-proof, gas-tight, liquid-impervious system that would transport human remains contaminated by chemical or biological agents.

New Technology Resources
Following are just a few of the web resources through which industry can stay updated on current research and development in new technologies and methods associated with food.

Food Safety and Inspection Service New Technology Information Table
http://www.fsis.usda.gov/regulations_&_policies/New_Technologies/index.asp#Tables
FSIS reviews new technologies to ensure that their use is consistent with regulations and will not adversely affect product safety, inspection procedures, or the safety of FSIS inspectors.

USDA  Research
http://www.ars.usda.gov/Research/docs.htm?docid=1414
USDA ARS research can be viewed from several perspectives, including location, national programs, and subject.

FDA Research
http://www.fda.gov/Food/ScienceResearch/ResearchAreas
This section describes areas of research in food safety, defense, processing, risk assessment, and foodborne illness, as well as consumer research in foods.

U.K. Food Standards Agency Research
http://www.food.gov.uk/science/research/
The research and survey work funded by the Food Standards Agency is focused on helping the agency understand food issues and meet its policy aims and objectives.

Newswise Food/Water Safety Section
http://www.newswise.com/articles/channels?channel=65
Newswise provides information on ongoing research in a variety of topic areas, including that related to food in all its aspects.

Other Organizations
Institute of Food Techonogists, http://www.ift.org
International Association for Food Protection,  http://www.foodprotection.org/
Federation of Animal Science Societies,
http://www.fass.org/page.asp?pageID=156&autotry=true&ULnotkn=true