Nakayama Tatsuya, Tuyet Hoa Tran Thi, Harada Kazuo, Warisaya Minae, Asayama Megumi, Hinenoya Atsushi, Lee Joon Won, Phu Tran Minh, Ueda Shuhei, Sumimura Yoshinori, Hirata Kazumasa, Phuong Nguyen Thanh, Yamamoto Yoshimasa
Global Collaboration Center, Osaka University, 2-7, Yamadaoka, Suita, Osaka, 565-0871, Japan; Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58, Rinku Ourai Kita, Izumisano, Osaka, 598-8531, Japan; Graduate School of Pharmaceutical Science, Osaka University, 1-6, Yamadaoka, Suita, Osaka, 565-0871, Japan.
College of Aquaculture and Fisheries, Can Tho University, Campus II, 3/2 Street, Ninh Kieu, Can Tho, Viet Nam.
Environ Pollut. 2017 Mar;222:294-306. doi: 10.1016/j.envpol.2016.12.041. Epub 2017 Jan 3.
The environmental pathways for the dissemination of antibiotic resistance have recently received increased attention. Aquatic environments act as reservoirs or sources of antimicrobial-resistant bacteria, antimicrobial residues, and antimicrobial resistance genes (ARGs). Therefore, it is imperative to identify the role of polluted water in the dissemination of antimicrobial resistance. The aim of this study was to evaluate the antimicrobial residues, ARGs, and microbiota in the freshwater systems of the Mekong Delta. We selected 12 freshwater sites from aquacultures and rivers in Can Tho, Vietnam and analyzed them for 45 antimicrobial residues and 8 ARGs by LC/MS/MS and real-time PCR, respectively. A 16S rDNA-based metagenomic analysis was conducted to characterize the water microbiota. Residues of sulfamethoxazole (10/12) and sulfadimidine (7/12) were widely detected, together with the sulfa-resistance genes sul1 (11/12) and sul2 (9/12). Additionally, sulfamethoxazole residues and the β-lactamase-resistance gene bla were detected in eight freshwater systems (8/12), suggesting that these freshwater systems may have been polluted by human activity. The metagenomic analysis showed that all the tested freshwater systems contained the phyla Proteobacteria, Actinobacteria, and Bacteroidetes, representing 64% of the total microbiota. Moreover, the Cai Rang River site (Ri-E), which is located at the merge point of wastewaters from backyard-based aquacultures, contained the genera Polynucleobacter, Variovorax, and Limnohabitans, representing more than 78.4% of the total microbiota. Bacterial diversity analysis showed that the Ri-E exhibited the lowest diversity compared with other regions. Principal coordinate analysis showed that the differences among water microbiotas in backyard-based aquacultures could be explained by the farmers' aquaculture techniques. In conclusion, this study demonstrated a collapse of bacterial diversity at the merge point of wastewaters from backyard-based aquacultures in the Mekong Delta.
抗生素耐药性传播的环境途径最近受到了更多关注。水生环境充当了抗微生物细菌、抗微生物残留和抗微生物耐药基因（ARGs）的储存库或来源。因此，确定受污染水在抗微生物耐药性传播中的作用势在必行。本研究的目的是评估湄公河三角洲淡水系统中的抗微生物残留、ARGs和微生物群。我们从越南芹苴的水产养殖区和河流中选取了12个淡水采样点，分别通过液相色谱/串联质谱法（LC/MS/MS）和实时聚合酶链反应（real-time PCR）分析了其中的45种抗微生物残留和8种ARGs。进行了基于16S核糖体DNA的宏基因组分析，以表征水体微生物群。广泛检测到了磺胺甲恶唑（10/12）和磺胺二甲嘧啶（7/12）的残留，以及磺胺耐药基因sul1（11/12）和sul2（9/12）。此外，在八个淡水系统（8/12）中检测到了磺胺甲恶唑残留和β-内酰胺酶耐药基因bla，这表明这些淡水系统可能已受到人类活动的污染。宏基因组分析表明，所有测试的淡水系统都含有变形菌门、放线菌门和拟杆菌门，占微生物群总数的64%。此外，位于后院水产养殖废水汇合点的丐让河采样点（Ri-E）含有多核杆菌属、贪噬菌属和栖泥杆菌属，占微生物群总数的78.4%以上。细菌多样性分析表明，与其他区域相比，Ri-E的多样性最低。主坐标分析表明，后院水产养殖水体微生物群之间的差异可以通过养殖户的养殖技术来解释。总之，本研究表明湄公河三角洲后院水产养殖废水汇合点的细菌多样性遭到破坏。
