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Microbiology's niche in farm country
By Carol Ford
From eNews, December 1, 2005
"Bacterial antibiotic resistance is a leading health care concern of the 21st century."
University of Minnesota, Morris (UMM), assistant professor of biology Timna Wyckoff begins all her grant proposals with the above statement. For her, the need for more research in antibiotic resistance is obvious.
"The main causes of death used to be pneumonia, TB, and other infectious diseases," says Wyckoff, a 1994 UMM alumna. "Then better sanitation and antibiotics replaced those top killers with cancer and heart disease. Now, antibiotic resistance is creating a new threat. But the public's awareness of the dangers of antibiotic resistance didn't really begin until a decade ago."
Not long after taking a teaching position at UMM in August 2001, Wyckoff began looking for a new area of research because her previous research wasn't a good fit at a small liberal arts college. "Medical microbiology and biochemistry are competitive areas of big bucks and big universities," she quips.
Wyckoff decided that at UMM, she could fill a useful niche by giving her microbiology research a local slant. "Since resistance to antibiotics fascinates me and I'm in a rural setting, why not find a way to apply that interest to agriculture?" she says.
Antibiotics are obviously a good thing because they help people live longer. But bacterial resistance creates a paradox. Each time antibiotics are used, resistant strains of the bacteria survive. Humans are becoming aware of the reasons why they should only use antibiotics when needed, but often don't know how those drugs are used on livestock.
"Most people don't know that over half of our country's antibiotic use is not for humans," Wyckoff points out.
Conventional farmers use antibiotics on their livestock for three reasons. Therapeutic--when an animal has a bacterial infection, it is treated with an antibiotic; preventative (or prophylactic)--antibiotics are given to animals in the absence of infection to prevent it; and as growth promoters--the major use of antibiotics in livestock.
"Almost all conventional livestock in the United States get antibiotics for growth, although we don't know exactly how it works," Wyckoff says. "Yet growth promoters are being banned in many countries, including Denmark and, more recently, all of the European Union."
"Most people don't know that over half of our country's antibiotic use is not for humans," Wyckoff says.
Wyckoff's research focuses on dairy cows because growth-promoting antibiotics are not used on milk cows; only therapeutic and prophylactic antibiotics are used. She wants to compare the antibiotic resistance of bacteria found in cows at conventional dairy farms to those at organic dairy farms, where antibiotic use is very limited.
In dairies, mastitis (inflammation of the mammary gland) is the biggest reason for antibiotic use. Antibiotics are introduced directly into the udder. Wyckoff uses her research assistants to help her gather milk samples from conventional and organic dairies and then they look for one type of bacteria associated with mastitis: Staphylococcus.
Wyckoff's students work on all the stages of the research: collecting samples, isolating the Staph bacteria, identifying bacteria to the species level, and determining the resistance profile.
A year after beginning the project, Wyckoff and her students are still collecting data.
"Our preliminary results suggest that bacteria on conventional farms are a bit more resistant than those on organic farms," she says. "The students presented posters on our results for UMM's Undergraduate Research Symposium last spring."
This fall, Wyckoff is using her semester leave to explore some of the questions that have surfaced in her research. "I'd like to know why different types of bacteria seem to show up at conventional vs. organic dairies. On organic farms, we see strains of Staphylococcus that are more susceptible to antibiotics," she says. "I also want to look at dairies transitioning to organic. Once the selective pressure of antibiotic use is gone, how long does it take for susceptible strains to out-compete the resistant strains of Staph?"
Edited from the original story in the UMM Science and Math Alumni Newsletter.