Researchers at NC State and UNC look to “good” stomach bacteria to help poultry fend off salmonella

relder@newsobserver.comMarch 1, 2013 

  • What is salmonella?

    Salmonella is a bacterium that causes diarrhea, fever and abdominal cramps in people. Symptoms begin 12 to 72 hours after infection and last four to seven days. Most people recover without treatment, although severe diarrhea in some cases requires hospitalization. Older people and young children have the highest health risks.

    Tips for preventing salmonella infection include:

    • Cooking poultry and ground beef until it is no longer pink in the middle. • Thoroughly washing all produce. • Washing hands, kitchen work surfaces and utensils with soap and water after contact with raw meat or poultry. • Never cutting vegetables or preparing other foods on unwashed surfaces that previously have been in contact with uncooked poultry or meat. • Avoiding uncooked eggs, including those sometimes found in foods such as Hollandaise sauce, tiramisu, homemade ice cream and raw cookie dough. • Not consuming unpasteurized milk. • Washing hands immediately after touching turtles and other reptiles, as well as chicks, ducks and birds. Source: Centers for Disease Control

— A team of scientists in Raleigh and Chapel Hill is working to achieve a salmonella-free line of poultry by manipulating bacteria that live in the intestines of chickens.

Researchers will try to identify microscopic elements in the birds’ intestines that might fend off salmonella, and then encourage those “good” bacteria to flourish, said Matthew Koci, associate professor in the Department of Poultry Science at N.C. State University.

“We will be looking to see if there are bugs in the chickens’ gut that can exclude salmonella, and therefore lower the risk they will carry a food-borne disease,” Koci said.

The attempt to create a salmonella-free chicken stems from research in microbiomes – or the set of bacteria, viruses and fungi that populate the intestines of animals, including humans. Microbiomes can influence a wide range of health factors, from disease resistance to digestion.

Uncooked poultry, meat and raw eggs are major sources of salmonella infection. About 42,000 cases of salmonella infection are reported each year in the United States, though the actual number is probably many times that because mild cases typically are not reported. About 400 people in the United States die from salmonella infections each year.

Vaccines now available can halt development of salmonella in chickens, but questions remain about their effectiveness, Koci said.

“From our project, we hope to learn how changing the microbiota can improve vaccination or even eliminate the need for the salmonella vaccine altogether,” he added.

‘Poultry don’t get sick’

The scientists also will explore why chickens can have salmonella bacteria in their stomach and yet not suffer any adverse affects themselves.

“Poultry don’t get sick from salmonella,” said Hosni Hassan, professor of microbiology at NCSU and the project’s lead researcher. “But when we eat the chicken, we get sick. We want to know how the microbiome of the chickens allows salmonella to survive there happily.”

The research on poultry is taking place at the Dearstyne Avian Health Center at NCSU, where about 200 day-old chickens arrived last week. Researchers at the center will collect “poop samples” weekly and send them to the microbiologists for study, Koci said.

The bacteria analysis is being done at the Microbiome Core Facility at UNC’s School of Medicine by facility director Andrea Azcarate-Peril and research associate María Belén Cadenas.

Their mission, Cadenas said, is to evaluate chickens that are fed regular diets, those fed diets supplemented with bacteria-enhancing substances, and those that have been given the salmonella vaccine. The resulting data are expected to help identify specific bacterial species that cause increased resistance to salmonella.

“There are many bacteria, especially in the intestinal tract, that are beneficial,” Cadenas added.

The work is funded by a $2.5 million U.S. Department of Agriculture grant that also includes a health-education component for a new food-safety curriculum for North Carolina schools.

“We are looking at the project two ways: in terms of eliminating salmonella from the poultry, and educating a new generation about how to handle food,” Hassan said.

The project is funded through June 2017. And while it might take longer to come up with a salmonella-free chicken, food-borne disease can be reduced in the meantime through development of a new food-safety curriculum, Koci said.

Nine teachers from the Kenan Fellows Program for Curriculum and Leadership Development are being chosen to work alongside the scientists to learn more about bacteria and diseases and then come up with a curriculum to take that knowledge into the classroom.

4-H involved

Leaders of 4-H, a youth development organization sponsored by the federal agriculture department, will work with the Kenan Fellows as part of the public health outreach effort. Amy Chilcote, a 4-H program manager, said the goal is to create materials that will work well not only in the classroom but also in more informal settings, such as community-based 4-H clubs.

“The Kenan Fellows will work with us in the summer, pre-pilot their lessons in their own classrooms this year, and in 2014 will come back and plan the logistics for a statewide pilot project,” Chilcote said.

Along with helping youngsters learn about food safety, the curriculum for older students will be designed to reinforce a budding interest in microbiotics and similar fields, Chilcote said.

Recent advances in computer analysis and DNA gene sequencing are speeding up the pace of discovery in the field of microbiomes and the role of microscopic organisms in health.

Hassan said the concept of probiotics – or the supplementing of “good” bacteria in the intestines – dates to the late 1800s, when Ilya Metchnikov, a Russian bacteriologist, promoted the idea that eating yogurt could strengthen an individual’s immune response.

“Back then, not many people believed him; a lot of people thought it was like selling snake oil,” Hassan said. “Now we know each species has a unique set of probiotics that can be customized for better health.”

Elder: 919-829-4528

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