Differential Role of Two-Component Regulatory Systems (<i>phoPQ</i>and <i>pmrAB</i>) in Polymyxin B Susceptibility of <i>Pseudomonas aeruginosa</i>

Polymyxins are often considered as a last resort to treat multidrug resistant P. aeruginosa but polymyxin resistance has been increasingly reported worldwide in clinical isolates. Polymyxin resistance in P. aeruginosa is known to be associated with alterations in either PhoQ or PmrB. In this study, mutant strains of P. aeruginosa carrying amino acid substitution, a single and/or dual inactivation of PhoQ and PmrB were constructed to further understand the roles of PhoQ and PmrB in polymyxin susceptibility. Polymyxin B resistance was caused by both inactivation and/or amino acid substitutions in PhoQ but by only amino acid substitutions of PmrB. Alterations of both PhoQ and PmrB resulted in higher levels of polymyxin B resistance than alteration of either PhoQ or PmrB alone. These results were confirmed by time-killing assays suggesting that high-level polymyxin resistance in P. aeruginosa is caused by alterations of both PhoQ and PmrB.

铜绿假单胞菌的多黏菌素耐药机制

铜绿假单胞菌是一种革兰阴性的条件性致病菌,是如今临床最常见的病原菌之一。近年来由于各类抗生素在临床和生活中的大剂量、不规范使用,使铜绿假单胞菌对目前几乎所有的抗生素都产生了耐药性。多黏菌素作为对革兰阴性细菌作用颇强的一种抗生素,成为了多重耐药铜绿假单胞菌感染的最后治疗手段之一。但是,对现阶段临床分离的铜绿假单胞菌样品分析表明,部分菌株已经逐渐表现出了对多黏菌素的耐药性。本文就铜绿假单胞菌对多黏菌素耐药机制的研究进行总结。