The increasing production and use of antibiotics is mirrored by the growing number of antibiotic resistance genes (ARGs), effectively reducing antibiotics' ability to fend off diseases in animals and people, according to a new study in the current issue of the Proceedings of the National Academy of Sciences that shows that China -- the world's largest producer and consumer of antibiotics -- does not monitor the use or environmental impact of antibiotics.
On Chinese commercial pig farms, researchers found 149 unique ARGs, some at levels 192- to 28,000-times higher than the control samples, said James Tiedje, Michigan State University distinguished professor of microbiology and molecular genetics and of plant, soil and microbial sciences, and one of the co-authors.
"Our research took place in China, but it reflects what's happening in many places around the world," Tiedje said. "The World Organization for Animal Health and the U.S. Food & Drug Administration have been advocating for improved regulation of veterinary antibiotic use because those genes don’t stay local."
Tiedje was part of a research team led by Yong-Guan Zhu of the Chinese Academy of Sciences.
Antibiotics in China are weakly regulated, and the country uses four times more antibiotics for veterinary use than in the U.S. Since the medicine is poorly absorbed by animals, 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, an announcement from Michigan State University said.
"It is urgent that we protect the effectiveness of our current antibiotics because discovering new ones is extremely difficult," Zhu said. "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."