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Mutating Bacteria; Researchers refine antimicrobial resistance monitoring

Mutating Bacteria; Researchers refine antimicrobial resistance monitoring

While there’s not a lot of surefire scientific evidence to suggest that the judicious use of antibiotics in cattle contributes to antimicrobial resistance in humans, a team of Texas Tech animal science researchers are actively monitoring the situation in a far-reaching pilot study, keeping a sharp eye out for new strains of the virulent superbugs.

“The levels of resistance among bacteria appear to be growing,” said Guy Loneragan, an epidemiologist and professor with Texas Tech’s Department of Animal and Food Sciences. “As a society, we need to control, or even reduce the level of resistance in bacteria as the rate of new antibiotic discovery is slowing,”

For decades cattle producers have pointed out that the antibiotics are essential if they’re to produce a safe and affordable beef supply. Still, the ability for bacteria and other pathogens to mutate and survive the drugs that could formerly be relied upon to destroy them has some segments of the public worry that overuse of antibiotics in animal feed could lead to antibiotic-resistant bacteria dangerous to humans.

“Part of the knowledge needed for control is better understanding of when and where resistance develops, and to what extent it moves between populations,” Loneragan said. “Antimicrobial resistance is highly complex; so for every complex issue, there’s a simple answer which is invariably wrong.”

Most developed countries have a surveillance program in place. In the United States, it’s the 15-year-old National Antimicrobial Resistance Monitoring System, a national surveillance program operated by the Center for Veterinary Medicine, the Centers for Disease Control and Prevention and the U.S. Department of Agriculture.

Today, the Texas Tech research team is conducting a pilot study to design a more relevant and efficient antimicrobial resistance monitoring system with the hopes that in the future, any decisions can be based on firm, scientific data, Loneragan said. Among the prominent bacterial strains under surveillance now are Salmonella, Escherichia coli, and Enterococcus, along with the infectious disease campylobacteriosis.

The project started in September 2011 and will continue through a portion of this year. The project is coordinated and funded by the USDA Agricultural Research Service and FDA. There are also several other collaborators from other universities, as well as government research stations. Decisions will be made based upon the results of this study upon completion that will possibly lead to further research.

Antimicrobial resistance is associated with increased risk of treatment failure; increased duration of illness; substantially increased health care costs; and increased risk of death. “We need to be able to take the middle ground, and openly evaluate both benefits and risk,” Loneragan said. “There’s a real likelihood for unintended consequences to broad-sweeping limitations on use.”

Written by Kelsey Fletcher

CONTACT: Guy Loneragan, Professor, Department of Animal and Food Sciences, Texas Tech University at (806) 742-2805 or



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