摘要

携带接合质粒的细菌具有通过水平基因转移传播抗生素抗性的潜力。据描述，抗生素抗性的选择和传播通过金属或抗生素等应激物增强，这些应激物可作为环境污染物发生。该研究旨在揭示在不同交配条件下医院流出物多药耐药性大肠杆菌菌株（H1FC54）的接合质粒组的组成。为了实现该目的，将质粒脉冲场凝胶电泳，光学作图分析和DNA测序与表型分析组合使用。观察到菌株H1FC54含有5个质粒，其中3个是接合的，其中两个，pH1FC54_330和pH1FC54_140，含有金属和抗生素抗性基因。在不存在或存在亚碲酸盐（0.5μM或5μM），亚砷酸盐（0.5μM，5μM或15μM）或头孢他啶（10mg / L）的情况下获得的转接合子，并在叠氮化钠（100mg / L）存在下选择四环素（16mg / L）呈现出不同的表型，与获得不同质粒组合相关，包括两个共整合质粒，310kbp和517kbp。证实了接合质粒组的可变组成，缀合过程中共整合物的形成，以及通过共整合转移不可转移的质粒，以及抗生素，亚砷酸盐和亚碲酸盐耐受性之间可能的关联。这些证据为理解抗生素抗性在环境中传播的分子和生理机制提供了有趣的见解。

Bacteria harboring conjugative plasmids have the potential for spreading antibiotic resistance through horizontal gene transfer. It is described that the selection and dissemination of antibiotic resistance is enhanced by stressors, like metals or antibiotics, which can occur as environmental contaminants. This study aimed at unveiling the composition of the conjugative plasmidome of a hospital effluent multidrug resistant Escherichia coli strain (H1FC54) under different mating conditions. To meet this objective, plasmid pulsed field gel electrophoresis, optical mapping analyses and DNA sequencing were used in combination with phenotype analysis. Strain H1FC54 was observed to harbor five plasmids, three of which were conjugative and two of these, pH1FC54_330 and pH1FC54_140, contained metal and antibiotic resistance genes. Transconjugants obtained in the absence or presence of tellurite (0.5 μM or 5 μM), arsenite (0.5 μM, 5 μM or 15 μM) or ceftazidime (10 mg/L) and selected in the presence of sodium azide (100 mg/L) and tetracycline (16 mg/L) presented distinct phenotypes, associated with the acquisition of different plasmid combinations, including two co-integrate plasmids, of 310 kbp and 517 kbp. The variable composition of the conjugative plasmidome, the formation of co-integrates during conjugation, as well as the transfer of non-transferable plasmids via co-integration, and the possible association between antibiotic, arsenite and tellurite tolerance was demonstrated. These evidences bring interesting insights into the comprehension of the molecular and physiological mechanisms that underlie antibiotic resistance propagation in the environment.

https://www.ncbi.nlm.nih.gov/pubmed/30611073