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Viruses to battle bacteria

bacteriophageViruses that infect bacteria may prove cleaner alternatives to antiobiotics

Most agricultural livestock in the U.S. receive antibiotics to prevent and treat infections that can spread through farms. But this practice kills off healthy bacteria in animals’ digestive tracks and pollutes the environment as the animals excrete the medicine. And it may also create bacteria that are resistant to antibiotics in both animals and humans.

Scientists at the College of Veterinary Medicine are developing a better solution. Rodrigo Bicalho, assistant professor of dairy production medicine, is working on an alternative treatment called bacteriophage (“phage”) therapy.

A bacteriophage is a virus that infects bacteria. They are among the most common biological entities on earth. Bicalho’s project, which is funded by the U.S. Department of Agriculture and the Cornell Center for a Sustainable Future, is focused on finding bacteriophages that can kill bacteria, and creating a cocktail of them that will ultimately replace antibiotic therapy in livestock.

But finding a new treatment is not a simple task. There are thousands, perhaps millions, of unique bacteriophages, and each one only impacts a specific species and strain of bacteria.

“A bacteriophage that is effective against one species of bacteria will not be active against another,” Bicalho said. “This has advantages, because you can target the bacteria you want to kill much more easily.”

But to create an effective treatment, Bicalho must find a combination of bacteriophages that will kill a wide range of bacteria strains and species.

To develop a broad-spectrum treatment, Bicalho is studying the genotype of common bacteria that infect livestock and the genotypes of the bacteriophages. “We are trying to find genetic markers that can predict what bacteriophages will be effective against a specific bacterium,” he explained.

To date, his lab has assembled two large collections of bacteriophages: one collection composed of phages active against the bacteria Pseudomonas aeruginosa, which causes respiratory, skin and urinary tract infections in both humans and cattle; and the second composed of phages that are active against E. coli, which causes gastrointestinal infections.

The lab is currently conducting a clinical trial of four bacteriophages to prevent skin infections in New York commercial dairy cattle.

“There is a lot to be learned, but I am confident we can find successful uses for bacteriophages,” Bicalho said.