Overexpression of Resistance-Nodulation-Cell Division Pump AdeFGH Confers Multidrug Resistance in Acinetobacter baumannii
Overexpression of Resistance-Nodulation-Cell Division Pump AdeFGH Confers Multidrug Resistance in Acinetobacter baumannii
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DOI：
10.1128/aac.00155-10
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发表时间：
2010-10-01
影响因子：
4.9
通讯作者：
Perichon, Bruno
中科院分区：
文献类型：
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作者：
Coyne, Sebastien;Rosenfeld, Nicolas;Perichon, Bruno
鲍曼不动杆菌是一种主要的医院病原体，其经常通过获得抗生素抗性基因和过度表达内在外排系统（例如RND外排泵AdeABC和AdeIJK）而发展多药耐药性。第三个RND系统通过研究自发突变体BM 4663和BM 4664来表征，所述自发突变体BM 4663和BM 4664分别在氯霉素和诺氟沙星存在下从AdeABC缺陷型和AdeIJK缺陷型衍生物A中选择。鲍曼不动杆菌BM 4652。它们对氟喹诺酮类、四环素-替加环素、氯霉素、克林霉素、甲氧苄啶、磺胺甲恶唑、十二烷基硫酸钠和染料如溴化乙锭、番红O和吖啶橙子表现出增强的耐药性。使用微阵列技术比较突变体与其亲本菌株的转录组，证明了编码RND外排系统的三个基因的过表达，命名为AdeFGH。在BM 4664中灭活AdeFGH恢复了与BM 4652相同的抗生素敏感性谱，表明AdeFGH在BM 4652中是隐蔽的，并且负责其突变体中的多药耐药性。RNA分析表明，这三个基因是共转录的。在40株A.鲍曼不动杆菌临床分离株，但测试的22个分离株中没有一个过表达泵基因。从临床分离株BM 4587中获得了过表达adeFGH的自发MDR突变体BM 4684，表明在携带adeABC-adeIJK的菌株中可以过表达adeFGH。一个开放的阅读框架，编码一个LysR型转录调控因子，命名为阿德尔，位于上游的adeFGH操纵子和转录在相反的方向。在三个adeFGH过表达突变体中发现了阿德尔突变，这表明它们负责AdeFGH的过表达。
Acinetobacter baumannii is a major nosocomial pathogen which frequently develops multidrug resistance by acquisition of antibiotic resistance genes and overexpression of intrinsic efflux systems, such as the RND efflux pumps AdeABC and AdeIJK. A third RND system was characterized by studying spontaneous mutants BM4663 and BM4664, which were selected in the presence of chloramphenicol and norfloxacin, respectively, from the AdeABC- and AdeIJK-defective derivative A. baumannii BM4652. They exhibited enhanced resistance to fluoroquinolones, tetracycline-tigecycline, chloramphenicol, clindamycin, trimethoprim, sulfamethoxazole, sodium dodecyl sulfate, and dyes such as ethidium bromide, safranin O, and acridine orange. Comparison of transcriptomes of mutants with that of their parental strain, using a microarray technology, demonstrated the overexpression of three genes that encoded an RND efflux system, named AdeFGH. Inactivation of AdeFGH in BM4664 restored an antibiotic susceptibility profile identical to that of BM4652, indicating that AdeFGH was cryptic in BM4652 and responsible for multidrug resistance in its mutants. RNA analysis demonstrated that the three genes were cotranscribed. The adeFGH operon was found in 36 out of 40 A. baumannii clinical isolates, but none of the 22 isolates tested overexpressed the pump genes. Spontaneous MDR mutant BM4684, overexpressing adeFGH, was obtained from clinical isolate BM4587, indicating that adeFGH can be overexpressed in a strain harboring adeABC-adeIJK. An open reading frame, coding a LysR-type transcriptional regulator, named adeL, was located upstream from the adeFGH operon and transcribed in the opposite direction. Mutations in adeL were found in the three adeFGH-overexpressing mutants, suggesting that they were responsible for overexpression of AdeFGH.