Environmental 'Gene-Swapping' May Play Part in Antibiotic Resistance

Study finds genes in soil, human-disease bacteria passing back and forth

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TUESDAY, Sept. 4 (HealthDay News) -- At least seven antibiotic-resistant genes have recently passed between soil bacteria and bacteria that cause human disease, according to a new study.

Further research is needed to determine how widespread this sharing is, and to what extent it could make disease-causing bacteria harder to control, said the researchers at Washington University School of Medicine in St. Louis.

"It is commonplace for antibiotics to make their way into the environment. Our results suggest that this may enhance drug resistance in soil bacteria in ways that could one day be shared with bacteria that cause human disease," first author and graduate student Kevin Forsberg said in a university news release.

For this study, the researchers analyzed the DNA of bacteria in soil samples collected at various locations in the United States. The findings were published recently in the journal Science.

The researchers said it's important to find the answers to many questions, such as: Did the genes pass from soil bacteria to human pathogens or vice versa? Are the genes just the tip of a vast reservoir of shared resistance? Did some combination of luck and a new technique for studying genes across entire bacterial communities lead to the discovery of the shared resistance genes?

While humans only mix their genes when they have children, bacteria regularly exchange genes throughout their lifecycles. That means that when a strain of bacteria develops resistance to antibiotics, it can share this ability not only with its descendants but also with other bacteria, the researchers explained.

"I suspect the soil is not a teeming reservoir of resistance genes. But if factory farms or medical clinics continue to release antibiotics into the environment, it may enrich that reservoir, potentially making resistance genes more accessible to infectious bacteria," study senior author Gautam Dantas, an assistant professor of pathology and immunology, said in the news release.

More information

The U.S. Food and Drug Administration has more about antibiotic resistance.

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