本文選題：鮑曼不動桿菌 + 替加環(huán)素　； 參考：《浙江大學》2015年博士論文

【摘要】：多重耐藥鮑曼不動桿菌已成為臨床抗感染治療的難題,替加環(huán)素對其具有很好的抗菌活性。替加環(huán)素具有抗菌譜廣、抗菌活性強、不良反應小,應用不受患者年齡、性別、病情的限制等優(yōu)點,使其在治療多重耐藥鮑曼不動桿菌中倍受關注。然而,抗生素應用的同時往往伴隨著細菌耐藥的產(chǎn)生。自2005年美國FDA批準替加環(huán)素應用臨床以來,2006年就分離到了替加環(huán)素敏感性降低的鮑曼不動桿菌菌株。目前越來越多的替加環(huán)素不敏感菌株或耐藥菌株不斷在臨床主要病原菌中被分離。替加環(huán)素耐藥或不敏感菌株中最常見的是鮑曼不動桿菌。本研究主要分三部分,逐步深入研究鮑曼不動桿菌替加環(huán)素耐藥機制。 第一部分主要通過PCR、熒光定量PCR、外排泵抑制劑抑制表型檢測、突變檢測等方法分析了RND外排泵對多重耐藥鮑曼不動桿菌替加環(huán)素耐藥機制的影響,結果顯示：在替加環(huán)素耐藥和敏感菌株中,外排泵基因adeB、adeG和adeJ廣泛存在。替加環(huán)素耐藥菌株外排泵表達水平明顯高于替加環(huán)素敏感菌株,主要表現(xiàn)為AdeABC高表達,是由雙組分調(diào)節(jié)系統(tǒng)adeS中ISAba-1插入突變所致。具有外排泵抑制劑抑制表型菌株約占替加環(huán)素不敏感菌株(MIC≥4mg/L)的65.6%。 第二部分通過在鮑曼不動桿菌標準菌株ATCC17978中查找并克隆tetX基因的同源基因——A1S3356基因,在鮑曼不動桿菌中研究A1S3356基因?qū)λ沫h(huán)素類抗生素和替加環(huán)素耐藥機制的影響。結果顯示在A1S3356過表達菌株中未檢測到四環(huán)素類抗生素和替加環(huán)素的敏感性發(fā)生明顯變化,說明在鮑曼不動桿菌中A1S3356不介導四環(huán)素類抗生素和替加環(huán)素耐藥。 第三部分,利用替加環(huán)素連續(xù)體外誘導試驗,誘導鮑曼不動桿菌標準菌株ATCC19606,獲得替加環(huán)素耐藥菌株19606-T8；利用二代高通量測序技術進行全基因組測序,通過比較基因組學和比較轉(zhuǎn)錄組學,以及基因回補、功能驗證試驗等,力求探討替加環(huán)素耐藥新機制以及替加環(huán)素對鮑曼不動桿菌的影響。研究結果顯示：trm基因缺失突變導致替加環(huán)素敏感性降低,野生型trm基因能夠回復替加環(huán)素敏感性。因此,除RND外排泵外,trm基因作為新機制在替加環(huán)素耐藥過程中發(fā)揮重要作用。同時在替加環(huán)素的作用下,鮑曼不動桿菌的一些耐藥基因、外排泵相關基因、膜孔蛋白和轉(zhuǎn)錄因子等表達水平明顯增高,以及代謝相關基因表達水平也發(fā)生改變等。
[Abstract]:Multidrug resistant Acinetobacter baumannii has become a difficult problem in clinical anti-infective therapy, and tegicycline has good antibacterial activity against it. Tegicycline has the advantages of wide antibacterial spectrum, strong antibacterial activity, small adverse reaction, and its application is not limited by age, sex and condition of the patient, so it has attracted much attention in the treatment of multidrug resistant Acinetobacter baumannii. However, antibiotic use is often accompanied by bacterial resistance. Acinetobacter baumannii strain with low sensitivity to tegicycline was isolated in 2006 since FDA approved the clinical application of tegicycline in 2005. At present, more and more tegacycline insensitive or resistant strains have been isolated from the main clinical pathogens. Acinetobacter baumannii is the most common strain of tegicycline-resistant or insensitive strains. This study was divided into three parts, and the mechanism of tegacycline resistance of Acinetobacter baumannii was studied step by step. In the first part, the effects of RND efflux pump on multidrug resistance of Acinetobacter baumannii were analyzed by means of PCR, fluorescence quantitative PCR, inhibition phenotype of efflux pump inhibitor, mutation detection and so on. The results showed that the efflux pump gene adeBnadeG and adeJ were widely present in tegacycline resistant and sensitive strains. The expression level of efflux pump in tegacycline resistant strains was significantly higher than that in tegacycline sensitive strains. The high expression of AdeABC was mainly caused by the insertion mutation of ISAba-1 in the two-component regulatory system (adeS). The strain with efflux pump inhibitors accounted for 65.6% of tegacin-insensitive strains (MIC 鈮，

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