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Antibiotic Pollution in Estuaries Is Leading to Antibiotic-Resistant Bacteria, Contaminating Seafood

Elizabeth Fox
31st January, 2017

Scientists from around the world, including researchers from Macquarie University, have found that antibiotic pollution is causing bacteria to develop antibiotic resistance—even in areas without human traffic. Human food, including oysters and salmon, are often sourced from estuarine habitats. This could lead to problems if people consume food that contains antibiotic-resistant bacteria. The research team’s findings were just published in the journal Nature Microbiology. Antibiotic pollution is a growing problem, especially in our waterways. When human patients or livestock are dosed with antibiotics, only a small concentration is actually absorbed. The rest passes through the body and can end up in waste water. Many people don’t properly dispose of unused antibiotics and may flush them down the toilet, adding to the problem. Current waste water treatments don’t remove these antibiotics and some end up in the environment, including nearby estuary regions. A team of researchers investigated the potential consequences of antibiotic pollution in estuaries, bodies of water found between marine and freshwater waterways. The team collected water samples along nearly 2,500 miles of China’s coastline. In this region, the team discovered that nearly every bacterial cell contained at least a single gene for antibiotic resistance. There were millions of antibiotic resistance genes detected in just one gram of estuarine sediment. In some areas, the team found 100 million genes for antibiotic resistance per gram of sediment. Although the study focused on China, the authors emphasize that this is a global problem. Other parts of the world likely have similar concentrations of antibiotic-resistant bacteria. This is a serious human health risk because seafood is often sourced from these regions. If an individual consumes seafood that was captured in an estuary, they may be exposed to dangerous bacteria that have become resistant to all common antibiotics. The results of the study show that antibiotic pollution extends to estuarine regions. Human food is sometimes fished from these areas, including salmon, sea trout, oysters, and shrimp. Consuming contaminated seafood could lead to dangerous infections with antibiotic-resistant bacteria. The study’s authors recommend that immediate actions are taken to reduce the risk of antibiotic pollution in waterways. REFERENCE Yong-Guan Zhu et al. Continental-scale pollution of estuaries with antibiotic resistance genes. Nature Microbiology (2017).