鲍曼不动杆菌rrf基因突变介导替加环素耐药机制研究

替加环素是治疗多重耐药鲍曼不动杆菌(MDRAB)感染的重要选择，随着替加环素的广泛使用，MDRAB对替加环素的耐药率不断上升，给抗感染治疗带来重大挑战。现已报道的MDRAB替加环素耐药机制，如外排泵、酶降解(tetX)、细菌膜渗透性改变，仍不能解释替加环素耐药率快速上升的原因。我们在前期MDRAB替加环素体外阶梯诱导耐药株中，发现编码核糖体循环因子的rrf基因出现一个点突变(H33P)，并通过突变重构证明该突变与替加环素敏感性下降相关。但rrf参与替加环素耐药的机制尚不清楚。本研究拟通过体外药敏和生长速度测定，明确rrf突变对MDRAB的适应性代价和替加环素耐药性的作用；通过测定不同条件下野生株和rrf突变株的rrf转录和蛋白水平的变化，结合多聚核糖体分析，明确rrf突变对其转录、表达及核糖体解离的作用，阐明rrf突变导致替加环素耐药的确切机制，为MDRAB替加环素耐药防控提供新策略。

Tigecycline is an important choice for the treatment of infections caused by multidrug resistance Acinetobacter baumannii (MDRAB). With the increasing usage of tigecycline, the resistance rate of tigecycline which were active against MDRAB were rapid increased, posing significant challenges to anti-infective treatment. However, resistance mechanisms to tigecycline in MDRAB, such as efflux pump, enzyme degradation (tetX) and the change of bacterial membrane permeability, can still not fully elucidate the rapid increase of resistance. In previous work, we performed an in vitro evolution experiment to select for an tigecycline resistant strain, and we found a point mutation in gene rrf (H33P), which encoding the ribosome recycling factor (RRF). And we performed reconstruction of this mutation to prove it was related to the decrease of tegacycline sensitivity. However, the mechanism of rrf involved in tegacyclin resistance is not clear. This study will determine the effect of rrf mutation on the fitness cost and antibiotic resistance of MDRAB. By measuring the changes of rrf transcription and protein level of the rrf mutant and the wild strain under different conditions, combined with polysome profiles analysis, the effects of rrf mutations on their transcription, expression and ribosome dissociation were determined. We hope to elucidate the mechanism of tigecycline resistance mediated by rrf mutation, which may provide a new strategy for rational application of tigecycline and MDRAB resistance control.