抑制广泛耐药鲍曼不动杆菌对多黏菌素产生耐药的联合给药策略的研究

Resistance in Acinetobacter baumannii becoming increasingly serious due to wide use of antibiotics with the super-broad spectrum, and the rate of Extensively Drug Resistant Acinetobacter baumannii (XDR-AB) isolated has been also going up for the years. Although these XDR-AB strains maintain a high sensitive to colistin (>90%) only, it's easy to convert to resistant once after colistin monotherapy. What's more, the clinically colistin-resistant Acinetobacter baumannii were found in many countries, which lead to unavailable antibiotics in practice. It is possible to combine colistin with other antibiotics for suppression of XDR-AB' resistance. Therefore, this project will focus on the following profiles: ① To simulate the development of XDR-AB' resistant to colistin by a vitro PK/PD model with the detected drug concentration in human, and then analyze the difference of lipopolysaccharide (LPS) structure between colistin resistant and susceptible isolates using mass spectrographic system, as well as compare the difference of their gene expression for interpretation of the colistin-resistant mechanism of XDR-AB. ② To establish a vitro PK/PD model of colistin combination regimen, simulate a variety of dosage regimens for the related PK/PD target ,and then , obtain an appropriate dosing regimen though Monte Carlo simulation. ③ To monitor bacterial resistance change in the combination therapy ,and to obtain combination regimen that can inhibit resistance of XDR-AB to colistin effectively though association analysis among drug concentration change, dynamic killing process and resistant mechanism.

随着超广谱抗生素的广泛应用，鲍曼不动杆菌（AB）耐药性日益严重，广泛耐药菌株(XDR)分离率逐年增加，这些XDR-AB仅对多黏菌素保持高的敏感率(>90%），然而体外研究发现多黏菌素单药使用容易诱导耐药，且对多黏菌素耐药的鲍曼不动杆菌临床菌株在多个国家已有报道，导致临床陷入彻底无药可用的困境。本课题拟从联合用药的角度探索可抑制XDR-AB对多黏菌素产生耐药的给药策略，拟重点开展以下研究：①采用体外PK/PD模型模拟临床实际药物浓度下XDR-AB对多黏菌素产生耐药的过程，通过质谱分析敏感菌与耐药菌LPS差异，基因克隆对比基因差异，探索耐药机制。②建立联合用药的体外PK/PD模型，模拟多种给药方案，得到相应的PK/PD靶值，通过蒙特卡洛模拟筛选给药方案。③监测联合用药过程中细菌耐药性变化，将药物浓度经时变化、杀菌动态过程、耐药机制研究结合起来，探索出可有效的抑制耐药性产生的联合给药策略。

多黏菌素是对广泛耐药鲍曼不动杆菌感染的最后一道防线，本课题针对多黏菌素在临床中应用的药代动力学特点、多黏菌素在临床中易产生耐药的问题，提出采用体外PK/PD模型对联合用药的方案进行优化。本课题完成了以下工作：①首先报道了中国健康志愿者以及医院获得性肺炎患者中单次静脉输注多黏菌素2.5mg/kg后的药代动力学特点，明确临床用药后的稳态谷浓度为1mg/L。②建立了体外PK/PD联合用药的模型。在体外PK/PD联合用药模型中模拟了多黏菌素稳态谷浓度与美罗培南在中国健康志愿者中的药代动力学特点下的多种用药组合方案，并与单药用药的方案进行比较，发现多黏菌素和美罗培南联合用药对广泛耐药鲍曼不动杆菌的协同作用，提出美罗培南2g，连续输注3h与多黏菌素2.5mg/kg给药后的稳态浓度有协同作用，可以有效抑制广泛耐药鲍曼不动杆菌转变为全耐药鲍曼不动杆菌。③在体外PK/PD研究过程中，发现多黏菌素单独用药易产生耐药，采用蛋白质组学对耐药机制进行了研究，发现了脂质A合成途径以及外排泵蛋白引起的多黏菌素耐药。同时采用基因组学研究发现广泛耐药鲍曼不动杆菌在患者用药过程中对头孢哌酮/舒巴坦逐渐产生耐药的一个原因为blaOXA-23表达的增加④本课题进一步延伸研究发现了多黏菌素和磷霉素联合治疗产碳青霉烯酶的肺炎克雷伯菌有很好的协同作用，本课题组目前对该联合用药的给药方案正进行体外PK/PD模型优化，抑制全耐药肺炎克雷伯菌。本研究为多黏菌素类药物在中国上市后的临床应用，以及选择合理的用药方案防止耐多黏菌素的全耐药菌出现具有重要意义。