MICHIGAN STATE (US) — The poorly regulated use of antibiotics in animal production is increasingly putting human health at risk with the spread of antibiotic resistant genes, experts warn.
A study published in the current issue of the Proceedings of the National Academy of Sciences shows that China—the world’s largest producer and consumer of antibiotics—and many other countries don’t monitor the powerful medicine’s usage or impact on the environment.
On Chinese commercial pig farms, researchers found 149 unique antibiotic resistant genes, or ARGs, some at levels 192 to 28,000 times higher than the control samples, says James Tiedje a professor of microbiology and molecular genetics and of plant, soil and microbial sciences at Michigan State University.
“Our research took place in China, but it reflects what’s happening in many places around the world,” says Tiedje. “The World Organization for Animal Health and the US Food and Drug Administration have been advocating for improved regulation of veterinary antibiotic use because those genes don’t stay local.”
Antibiotics in China are weakly regulated, and the country uses four times more antibiotics for veterinary use than in the United States. Since animals poorly absorb the medicine, much of it ends up in manure—an estimated 700 million tons annually from China alone.
This is traditionally spread as fertilizer, sold as compost, or ends up downstream in rivers or groundwater, taking ARGs with them. Along with hitching rides in fertilizer, ARGs also are spread via international trade, immigration, and recreational travel.
Daily exposure to antibiotics, such as those in animal feed, allows microbes carrying ARGs to thrive. In some cases, these antibiotic resistant genes become highly mobile, meaning they can be transferred to other bacteria that can cause illness in humans.
This is a big concern because the infections they cause can’t be treated with antibiotics.
ARGs can reach the general population through food crops, drinking water, and interactions with farm workers. Because of this cycle, ARGs pose a potential global risk to human health and should be classified as pollutants, says Tiedje.
“It is urgent that we protect the effectiveness of our current antibiotics because discovering new ones is extremely difficult,” says researcher Yong-Guan Zhu of the Chinese Academy of Sciences.
“Multidrug resistance is a global problem and must be addressed in a comprehensive manner, and one area that needs to be addressed is more judicious use and management of wastes that contain ARGs.”
Source: Michigan State University