Researchers Discover Recipe for Antibiotic Resistant Bacteria

A novel recipe for antibiotic resistant bacteria has been created by researchers at the Washington State University.

The recipe consists of a mix of cow dung, soil and urine. The E.coli in the dung soil mixture is killed with urine, but some of these antibiotic-resistant E.coli survive in the soil to recolonize in a cow's gut through pasture, forage or bedding.

"I was surprised at how well this works, but it was not a surprise that it could be happening," says Doug Call, a molecular epidemiologist in WSU's Paul G. Allen School for Global Animal Health. Call led the research with an immunology and infectious disease Ph.D. student, Murugan Subbiah.

Antibiotics  have drastically reduced infections in the past, but their indiscriminate use has led to wide-spread resistance. Most microbes are developing resistance to them leading to lengthy medical supervisions.

For this study, the researchers focused on the antibiotic ceftiofur, a cephalosporin that promotes resistance in bacteria like Salmonella and E.coli.

According to Call, Ceftiofur has little impact on gut bacteria.

"Given that about 70 percent of the drug is excreted in the urine, this was about the only pathway through which it could exert such a large effect on bacterial populations that can reside in both the gut and the environment," he says.

Call's research questions the conventional thinking that believed antibiotic resistance was developed inside the animal.

"If our work turns out to be broadly applicable, it means that selection for resistance to important drugs like ceftiofur occurs mostly outside of the animals," he says. "This in turn means that it may be possible to develop engineered solutions to interrupt this process. In doing so we would limit the likelihood that antibiotic resistant bacteria will get back to the animals and thereby have a new approach to preserve the utility of these important drugs."

The researchers believe that if a way is found to isolate and dispose the residual antibiotic which animals excrete before it mixes with the bacteria present in soil, it will tremendously benefit mankind.

The experiments were performed in labs using materials from dairy calves.  The study appears in a recent issue of the online journal PLOS ONE.