Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
Environmental Microbiology and Biotechnology Laboratory, Department of Microbiology, University of Ibadan, Ibadan, Nigeria.
PLoS One. 2020 Mar 4;15(3):e0229451. doi: 10.1371/journal.pone.0229451. eCollection 2020.
In many countries, emission of insufficiently treated wastewater into water bodies appears to be an important factor in spreading clinically relevant antimicrobial resistant bacteria. In this study, we looked for the presence of Enterobacteriaceae strains with resistance to 3rd generation cephalosporin antibiotics in four urban wetlands in southwestern Nigeria by isolation, whole genome sequencing and qPCR enumeration of marker genes. Genome analysis of multi-drug resistant and potentially pathogenic Escherichia coli isolates (members of the widely distributed ST10 complex) revealed the presence of the extended spectrum beta-lactamase gene blaCTX-M-15 on self-transmissible IncF plasmids. The gene was also present together with a blaTEM-1B gene on self-transmissible IncH plasmids in multi-drug resistant Enterobacter cloacae isolates. A Citrobacter freundii isolate carried blaTEM-1B on an IncR-type plasmid without discernable conjugation apparatus. All strains were isolated from a wetland for which previous qPCR enumeration of marker genes, in particular the ratio of intI1 to 16S rRNA gene copy numbers, had indicated a strong anthropogenic impact. Consistent with the isolation origin, qPCR analysis in this study showed that the blaCTX-M gene was present at an abundance of 1x10-4 relative to bacterial 16S rRNA gene copy numbers. The results indicate that contamination of these urban aquatic ecosystems with clinically relevant antibiotic resistant bacteria is substantial in some areas. Measures should therefore be put in place to mitigate the propagation of clinically relevant antimicrobial resistance within the Nigerian aquatic ecosystems.
在许多国家，将未经充分处理的废水排放到水体中似乎是导致具有临床相关性的抗微生物耐药细菌传播的一个重要因素。在这项研究中，我们通过分离、全基因组测序和 qPCR 计数标记基因，在尼日利亚西南部的四个城市湿地中寻找对第三代头孢菌素类抗生素具有耐药性的肠杆菌科菌株。对多药耐药和可能具有致病性的大肠杆菌分离株（广泛分布的 ST10 复合体的成员）的基因组分析显示，在可自我转移的 IncF 质粒上存在扩展谱β-内酰胺酶基因 blaCTX-M-15。该基因也存在于多药耐药阴沟肠杆菌分离株的可自我转移的 IncH 质粒上，同时存在 blaTEM-1B 基因。一株弗氏柠檬酸杆菌携带 blaTEM-1B 基因在 IncR 型质粒上，没有明显的接合装置。所有菌株均从一个湿地中分离出来，该湿地先前的 qPCR 标记基因计数，特别是 intI1 与 16S rRNA 基因拷贝数的比值，表明该湿地受到强烈的人为影响。与分离来源一致，本研究的 qPCR 分析表明，blaCTX-M 基因的丰度为 1x10-4 ，相对于细菌 16S rRNA 基因拷贝数。结果表明，这些城市水生生态系统中临床相关的抗生素耐药菌的污染在某些地区相当严重。因此，应采取措施减轻尼日利亚水生生态系统中临床相关抗微生物耐药性的传播。
