摘要

       有关撒哈拉以南非洲国家水生环境中新出现的生物污染物，如抗生素抗性基因 (ARG) 和粪便指示菌 (FIB) 的数据是有限的。另一方面，抗生素耐药性仍然是一个世界性问题，可能对人类和动物健康构成严重的潜在风险。因此，越来越多的报告涉及这些污染物在各种环境中的流行和传播。沉积物提供了重建污染历史和评估影响的机会，因此本研究调查了从医院废水中释放的有毒金属、FIB 和 ARG 的丰度和分布以及它们在河流沉积物接收系统中的存在。 ARG（blaTEM、blaCTX-M、blaSHV 和 aadA）、细菌总量和选定的细菌物种 FIB [大肠杆菌、肠球菌 (ENT)] 和物种 (Psd) 通过使用定量 PCR (qPCR) 靶向物种特异性基因进行量化从刚果民主共和国金沙萨市的 4 个医院出口管道 (HOP) 及其河流接收系统中回收的沉积物中提取的总 DNA。结果突出了 HOP 中有毒金属的高浓度，达到了 47.9 (Cr)、213.6 (Cu)、1434.4 (Zn)、2.6 (Cd)、281.5 (Pb) 和 13.6 的值（mg kg-1） (汞)。结果还突出了所有采样点（包括上游（控制点）、排放点和接收河流下游）的 16S rRNA、FIB 和 ARGs 拷贝数的最高值（P < 0.05），表明医院出水不是进入城市河流的生物污染物的唯一来源。在 (i) 所有分析的 ARG 和总细菌负荷 (16S rRNA) 0.51 至 0.72（p < 0.001，n = 65）之间观察到显着相关性； (ii) ARGs（blaTEM 除外）和 FIB 和 Psd 0.57 < r < 0.82（p < 0.001，n = 65）； (iii) ARG（blaTEM 除外）和有毒金属（Cd、Cr、Cu 和 Zn）0.44 至 0.72，（p < 0.001，n = 65）。这些发现表明，包括医院和城市废水在内的几种来源有助于有毒金属和新出现的生物污染物在水生生态系统中的扩散。

       Data concerning the occurrence of emerging biological contaminants such as antibiotic resistance genes (ARGs) and fecal indicator bacteria (FIB) in aquatic environments in Sub-Saharan African countries is limited. On the other hand, antibiotic resistance remains a worldwide problem which may pose serious potential risks to human and animal health. Consequently, there is a growing number of reports concerning the prevalence and dissemination of these contaminants into various environmental compartments. Sediments provide the opportunity to reconstruct the pollution history and evaluate impacts so this study investigates the abundance and distribution of toxic metals, FIB, and ARGs released from hospital effluent wastewaters and their presence in river sediments receiving systems. ARGs (blaTEM, blaCTX-M, blaSHV, and aadA), total bacterial load, and selected bacterial species FIB [Escherichia coli, Enterococcus (ENT)] and species (Psd) were quantified by targeting species specific genes using quantitative PCR (qPCR) in total DNA extracted from the sediments recovered from 4 hospital outlet pipes (HOP) and their river receiving systems in the City of Kinshasa in the Democratic Republic of the Congo. The results highlight the great concentration of toxic metals in HOP, reaching the values (in mg kg−1) of 47.9 (Cr), 213.6 (Cu), 1434.4 (Zn), 2.6 (Cd), 281.5 (Pb), and 13.6 (Hg). The results also highlight the highest (P < 0.05) values of 16S rRNA, FIB, and ARGs copy numbers in all sampling sites including upstream (control site), discharge point, and downstream of receiving rivers, indicating that the hospital effluent water is not an exclusive source of the biological contaminants entering the urban rivers. Significant correlation were observed between (i) all analyzed ARGs and total bacterial load (16S rRNA) 0.51 to 0.72 (p < 0.001, n = 65); (ii) ARGs (except blaTEM) and FIB and Psd 0.57 < r < 0.82 (p < 0.001, n = 65); and (iii) ARGs (except blaTEM) and toxic metals (Cd, Cr, Cu, and Zn) 0.44 to 0.72, (p < 0.001, n = 65). These findings demonstrate that several sources including hospital and urban wastewaters contribute to the spread of toxic metals and biological emerging contaminants in aquatic ecosystems.

https://www.frontiersin.org/articles/10.3389/fmicb.2016.01128/full