ABSTRACT

The heavy use of antibiotics has caused the rise of antimicrobial resistance in the aquatic environment, which leads to the serious antibiotic resistance genes (ARGs) issues, posing a serious threat to ecological safety and human health. In this paper, we investigate the distributions of 10 antibiotics and 10 ARGs. The results have shown that sulfamerazine and tetC were the dominant antibiotic and ARG in the estuarine environment. intI1 plays the key role on the propagation of ARGs. Results in this paper provide data support and scientific basis for the control of antibiotics and ARGs pollution in the Yangtze River Estuary.

INTRODUCTION

Antibiotics are widely used in human and veterinary medicines in animal husbandry and aquaculture (Qiao, 2018). The total use of 36 antibiotics in China was estimated to be as high as 92,700 tons in 2013, which is the largest producer and user of antibiotics in the world (Zhang, 2015). The overuse of antibiotics seriously accelerated the acquisition and dissemination of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) (Huang, 2019). As a novel environmental pollutant (Pruden, 2006), the World Health Organization has proposed microbial resistance, i.e., ARGs, as one of the most serious threats to human health in the 21st century (Zheng, 2017). As an important mobile genetic element (MGE), integrons can capture and carry antibiotic resistance genes through the site-specific recombination system of gene cassettes, leading to the dissemination and horizontal transfer of ARGs (Zhu, 2013). ARGs have become not only an important research topic in environmental science but also a global public health crisis (WHO, 2015; Huang, 2019).

Aquatic ecosystems are ideal settings for the acquisition and dissemination of antibiotics and ARGs (Zhu, 2017). ARGs in estuarine environments are affected by both human activities and hydrometeorological factors during combined physical–chemical–biological processes (Jiao, 2007). Previous studies have shown that environmental factors (including temperature, pH, and TOC), antibiotics, heavy metals, and microbial communities are all strongly correlated with the distribution and dissemination of ARGs (Wang, 2020; Zheng, 2017; Guo, 2018). A variety of antibiotics and ARGs, such as tetracyclines, sulfonamides, and aminoglycosides, have been detected in most estuaries in China (Zhu, 2017; Chen, 2019; Lu, 2019), but the occurrence and distribution of antibiotics and ARGs in water and sediments in the coastal areas of the Yangtze River Estuary remained unknown.

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