Avoiding antibiotic resistance in turkeys
Date of publication : 7/29/2008
Source : Univ. of Arkansas Agricultural Experiment Station
A University of Arkansas-led research team has found that an effective way to get rid of pathogenic Campylobcter bacteria in turkeys is to use proteins produced naturally by other bacteria. The proteins are called bacteriocins. The researchers found that these proteins can eliminate the detectable Campylobacter and that they can also change conditions in the gut so that the pathogen has fewer places to hide and develop.
“If we can eliminate Campylobacter, we don’t have to worry about antibiotic resistance,” said Dan Donoghue, a UA Division of Agriculture poultry science researcher who led the project funded by the Food Safety Consortium. The UA group worked with USDA Agricultural Research Service scientists led by Annie Donoghue in Fayetteville, Ark., and Norm Stern in Athens, Ga., along with several Russian government microbiologists.
Campylobacter, which is one of the leading bacterial causes of foodborne illness, has often been the target of antibiotic treatment in poultry. But that approach has its disadvantages. Donoghue explained that the concern is that the Campylobacter in poultry will become resistant to the antibiotics, and that will lead to human consumers becoming sick.
Antibiotics, however, serve useful purposes to prevent disease or to treat sick birds. So the solution is to eliminate the Campylobacter through other means – in this case, bacteriocins – and then that also eliminates the problems in using antibiotics in poultry for other purposes.
“If there isn’t any Campylobacter in poultry, then it can’t become drug resistant,” Donoghue said. “The use of bacteriocins may allow antibiotics treatment of sick birds without the consequence of antibiotic-resistant Campylobacter.”
Although bacteriocins are effective at eliminating detectable levels of Campylobacter, that leads to the question of what about undetectable levels of the pathogen that might still be in the bird’s system. Donoghue noted that any possible remaining numbers of the pathogen can recolonize inside the bird within a few days. But if the birds are administered doses of bacteriocins just before processing, then the potential problem goes away.
“By the time the bird would get to the consumer, those numbers of Campylobacter – if they do exist – would be at such a low level that they wouldn’t pose a risk to human health,” Donoghue said.
Donoghue’s project is also exploring the effects that bacteriocins have on the bird’s guts. The bacteriocins, after three days of doses, appear to reduce the size of the bird’s crypts (narrow but deep pockets in the intestinal wall), which is where Campylobacter is sequestered.
“It is possible the smaller crypt size, and subsequent greater exposure to the intestinal lumen (cavity area) may change the nutrient or chemical environment limiting Campylobacter growth and colonization,” Donoghue said.
The bacteriocins also appear to reduce the number of goblet cells in a bird’s intestines. The goblet cells excrete mucin, a glycoprotein that serves as an energy source for Campylobacter.
“Since there are fewer goblet cells, that may mean there are less available nutrients to support Campylobacter growth” Donoghue said.
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