More than 200 resistance genes were found in sediments from estuaries from near the border with North Korea to the border just east of Vietnam, a Chinese-led team reported in Nature Microbiology.
Resistance genes against vancomycin were found in all estuaries. This suggest that wastewater from medical centers could be a source, the study said, because vancomycin is an antibiotic of last resort.
The study was published in Nature Microbiology. It can be found at j.mp/antresis. Researchers led by Yong-Guan Zhu of the Chinese Academy of Sciences studied 90 sediment samples from 18 estuaries.
Widespread use of antibiotics is known to encourage evolutionary selection for resistant bacteria. Moreover, these antibiotics are making their way into the water.
"A recent study estimated a total of 53,800 tons of antibiotics were released to rivers and waterways in China during 2013, which raises general concerns about the effects of environmental exposure to antibiotics," the study stated.
Signs of these antibiotics were found in estuary sediments, confirming that they had reached the coastal environment.
"Antibiotic residue and its correlation with ARGs (antibiotic resistance genes) suggest a significant degree of selection by antibiotic pollutants, either by direct selection or by co-selection via linkage with other resistance determinants," the study said.
Previous Chinese antibiotic resistance studies had been conducted on a much smaller scale of a single river or estuary, the article said. This one is the first to give a comprehensive look at coastal waterways in China.