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Antibiotic resistance genes a growing problem in chinese estuaries


Courtesy of Fluence Corporation

Large amounts of antibiotic resistance genes (ARGs) have been found throughout estuaries in coastal China, and scientists say they’re causing potentially dangerous changes to local bacteria.

When bacteria mutate and become resistant to antibiotics, it endangers human health and life. If antibiotics can’t work properly, infectious diseases will increase, and health-care costs will rise.

A team of international researchers, led by Professor Zhu Yongguan of the Institute of Urban Environment, Chinese Academy of Sciences, said the estuaries — areas where land, fresh water, and seawater meet — contained both antibiotic agents and antibiotic-resistance genes, which entered the waterways via human activity.

Water along roughly 4,000 kilometers (about 2,500 miles) of China’s coastline was surveyed and 90 sediment samples were taken. Scientists found that estuaries generally had levels of antibiotic resistance gene pollution of about 1 million resistance genes per gram of estuarine sediment. In other areas, the levels approached 100 million per gram.

Environmental Filters

The health of estuaries is vital to both terrestrial and aquatic environments. They often act as environmental filters since they are located between fresh and salt water. The NOAA Ocean Service Education explained:

One reason that estuaries are such productive ecosystems is that the water filtering through them brings in nutrients from the surrounding watershed  [T]hat same water often brings with it all of the pollutants that were applied to the lands in the watershed. […] Estuaries are some of the most fertile ecosystems on Earth, yet they may also be some of the most polluted.

This team of researchers — which also included scientists from the University of Hong Kong, Tsinghua University, and Macquarie University — found more than 200 types of resistance genes. Eighteen of those were found in all the sediment samples tested, which they say indicates a variety of genes that could lead to the formation of superbugs in the estuaries.

On average, there was about one ARG able to trigger resistance in each bacterial cell examined.

ARGs in Wastewater

A previous study found bacteria with an ARG tied to severe infections may be spreading through wastewater treatment plants in northern China. The gene is called New Delhi metallo-β-lactamase, or NDM-1. In the United States, the City of Flagstaff, Arizona, discovered antibiotic-resistant bacteria in its reclaimed water system; however, opinions diverge as to whether the bacteria could ultimately harm residents

That report explains:

Antibiotic resistance is a growing problem and is a major challenge to human medicine because it results in drugs losing their effectiveness for treating bacterial infections.

“Contaminants of emerging concern” is a term generally used to describe potential water pollutants that aren’t monitored or regulated in the U.S., including ARGs, as well as hormones, personal care products, insecticides, and prescription and over-the-counter medications. Pharmaceutical wastes and other contaminants of emerging concern are causing unknown impacts on aquatic life and water quality worldwide, which scientists have said makes additional research into this issue essential.

Human Activity Blamed

In this recent study, no specific geographical patterns were determined from the analysis. The researchers say human activity is to blame for the prevalence of these genes in the waters. They added:

[T]he major cause of the accumulation of these genes in the environment is human activity, and the failure of waste water treatment plants to remove these genes during processing — something that we need to focus on achieving in the future. Otherwise, we could find ourselves facing dire environmental, agricultural and medical consequences.

These findings — “Continental-Scale Pollution of Estuaries With Antibiotic Resistance Genes” — were published in the journal Nature Microbiology.

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