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NC A&T: Keeping Healthy Foods Healthy For Us

November 03, 2011

NC A&T: Keeping Healthy Foods Healthy For Us

NC A&T’s Center for Excellence in Post Harvest Technologies at the NCRC researches the pathogens that cause foodborne illness in order to find ways to keep food free of contaminates and to develop more effective treatments.

No one wants to dine with Listeria monocytogenes, Salmonella, Staphylococcus aureus, E. coli 0157:H7 or any of the 31 known microorganisms that cause foodborne illnesses. Unfortunately, millions of us do.

The Centers for Disease Control and Prevention (CDC) reports that annually these types of pathogens, cause over 48 million illnesses, 128,000 hospitalizations and over 3,000 deaths, mostly in people who are young, elderly, pregnant or immunocompromised.

Since these pathogens are in the environment, living in everything from soil to skin, consumers can take preventative action by following guidelines available at websites like www.befoodsafe.org. Permanently reducing or eliminating incidents of foodborne illness and developing effective treatments is dependent on the research of institutions like North Carolina Agricultural and Technical State University’s (NC A&T) Center for Excellence in Post Harvest Technologies (CEPHT) located at the North Carolina Research Campus in Kannapolis.


CEPHT’s Mission

williamsLeonard L. Williams, PhD, CEPHT’s interim director, lead scientist and associate professor of food microbiology and biotechnology, heads a research team of 23 including three other scientists, research technicians, post-doctoral researchers, undergraduate students and even high school apprentices. CEPHT’s focus spans food safety; food processing, packaging and engineering; product development and consumer science; and functional foods and bioactive compounds.

Williams’ expertise is food safety. “Pathogens cause a lot of deaths, sickness and hospitalization which results in a tremendous economic burden with loss of work and doctor visits and on the food industry with recalls and lawsuits,” he said. “It exponentially compounds itself to where it’s (foodborne illness) probably one of the most costly to treat. It is something we hope to help find a remedy for through the research in this center.”

Williams’ priority is to find natural alternatives such as phytonutrients or phytochemicals from plants that are known to have antimicrobial properties. Published September 2011 in the Journal of Medicinal Food, Williams with co-investigators from Alabama A&M University found that sorrel (Hibiscus sabdariffa), a perennial herb, has antimicrobial activity that can inhibit E. coli O157:H7.

“This is the type of work we are trying to focus on comparing natural alternatives to the synthetic alternatives such as the antibiotics that we take,” Williams said. “Bacteria have the ability to acquire resistance and mutate consistently. With natural extracts, they have not quite figured out how to change their genetic material to become resistant. That’s the reason a lot of companies and universities are looking at interventions using natural extracts.”


Fighting Pathogens

Williams’ is part of studies that track the source of pathogens. On farms, for example, pathogens are linked to waste run-off from grazing livestock that enters water used for irrigation. “MRSA (methicillin-resistant Staphylococcus aureus) research could potentially change agricultural practices, especially when you are talking about animal husbandry. How animals acquire antimicrobial resistance, and how it is disseminated from animals to plants, plants to humans and from humans back to animals. That perpetual cycle creates problems in our food system.”

MRSA is a common pathogen on skin that is resistant to many antibiotics and associated with hospital-acquired infections. MRSA is found in products like unpasteurized milk and on the surface of salad crops. “Unfortunately, the therapeutic agents we use for treating MRSA infections are now being excreted in our waste. They are being excreted in animal waste,” Williams said. “A lot of animal by-products are being used for fertilizers, which can potentially be introduced to our fruits and vegetables. We are looking at ways to isolate these organisms, identify them, type them using DNA fingerprinting as well as determining antimicrobial resistance profiles and susceptibility profiles.”

Williams’ is also leading a study to track, test and isolate Verotoxin-producing E. coli (VTEC), Salmonella, Listeria monocytogenes and Staphylococcus aureus on lettuce, green onions, sprouts and spinach in North Carolina, California, the US Midwest and Mexico. “These products have been implicated in the most recalls,” Williams said. “They are the riskiest at this point. We want to focus on the risky products because we consume fruits and vegetables raw or minimally cooked.”

Just this year, cantaloupe was the carrier identified in 72 listeria infections, including 13 deaths, in 18 states. Listeria is a soil-borne organism that grows at refrigerated temperatures and can be found in milk, meat, ready-to-eat products, fruits, vegetables and salad products. Williams is researching how listeria develops antimicrobial resistance.

“Listeria can adapt to antimicrobial therapeutic doses and treatments,” he said. “We are looking at how it is able to survive when treated. A group of specific genes called gyrase A, B and par C mutates. If it mutates, it makes the bug more resistant to sanitizers, disinfectants and antimicrobial agents. We are trying to find ways to elucidate the mechanisms.”

Another common pathogen passed through contaminated food is norovirus. CDC statistics show norovirus causes over 5.4 million illnesses a year. NC A&T is one of six co-leading institutions and 19 total universities and organizations coordinating a $25 million, five-year grant from the US Department of Agriculture with the purpose of reducing the effects of norovirus.

Williams doesn’t spend all of his time looking at what makes people sick. For a dried ingredients company, he is determining nutritional profiles for their products and evaluating product safety. No matter the specific research, the goal is to keep the healthiest foods healthy for consumers from the field to the fork.

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