Antibiotics: Resistance alarm on China's shores

Millions of resistance genes in every gram of Mündungsgebiete

Methicillin-resistant Staphylococcus aureus (MRSA) is one of many antibiotic resistant bacteria. © CDC
Read out

Alarming find: The coast of China is contaminated with resistant bacteria. Researchers have detected massive resistance genes in sediment in all large estuaries along the coast - millions of gene copies per gram of mud. These
make immune against almost all known antibiotic classes, as the scientists in the journal "Nature Microbiology" report.

Antibiotic resistance is increasing worldwide. Even in Europe many pathogens are already immune to the once sharpest weapons of medicine. The main cause, in addition to unnecessarily prescribed antibiotics, is the use of antibiotics in animal husbandry. Especially China is considered as inglorious leader.

Millions of resistance genes per gram of mud

How big the problem really is now revealed by a study by Yong-Guan Zhu of the Chinese Academy of Sciences and his colleagues. They analyzed the sediments of 18 large estuaries along the east coast of China for resistance genes. Overall, they took 90 samples along the 4.00 kilometer long coastline.

The shocking result: In each sample, the scientists found massive resistance genes - no matter where the sediment came from. "Their numbers ranged from just under 900, 000 to 180 million gene copies per gram of sediment, " Zhu and his colleagues report. "This proliferation of such resistance in the aquatic environment is alarming."

Immune to almost all classes of drugs

Not only the sheer numbers, but also the variety, as the researchers emphasize, are a matter of concern. "The resistance genes found make them immune to almost all classes of antibiotics used in humans and animals, " they report. "Their variety is even higher than in samples from Chinese pig farms." Ad

Number of different resistance genes at the sample sites. Zhu et al. / Nature Microbiology

Some of the 256 different genes deactivate the antibiotics, others help the bacteria to eliminate the agent, and yet others prevent the drug from penetrating the cell wall of the bacteria. "Genes that are equally resistant to multiple antibiotic classes were common and present in many variants, " said Zhu and his colleagues.

Particularly alarming: In all Mündungsgebieten the scientists also found resistance genes against vancomycin with millions of copies per gram of mud. These reserve antibiotics are usually only given when other, more affordable drugs are no longer helpful. However, the bacteria in the sediment have evidently long since developed defense strategies against these weapons of medicine.

Wastewater and aquaculture as the main culprits

But where does this resistance glut come from? The researchers found that the resistance genes were found particularly where population density was high on land and much aquaculture and agriculture were used. In addition, the coastal sludge also contained large amounts of antibiotics of different classes - the more of these were present, the more resistance genes were also found.

"This suggests that urban wastewater and aquaculture are flooding significant amounts of resistance genes into the mouths, " say the scientists. The presence of resistance genes to vancomycin also suggests that medical facilities could also be an important source. If nothing is done to prevent this massive spread of environmental resistance in the future, this could have serious consequences for agriculture, the environment and human health, the researchers emphasize. (Nature Microbiology, 2017; doi: 10.1038 / nmicrobiol.2016.270)

(Chinese Academy of Sciences, 15.02.2017 - NPO)