Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Department of Medical Techniques, Taipei City Hospital Ren-Ai Branch, Taipei, Taiwan.
Clin Microbiol Infect. 2019 Apr;25(4):512.e1-512.e6. doi: 10.1016/j.cmi.2018.06.012. Epub 2018 Jun 12.
Tigecycline non-susceptible Acinetobacter nosocomialis (TNAN) has been discovered in clinical isolates. The resistance-nodulation-cell division (RND)-type efflux system plays a major role in tigecycline non-susceptible Acinetobacter baumannii, but the mechanism in A. nosocomialis remains unknown. Our aim was to analyse the contribution of efflux-based tigecycline resistance in clinical A. nosocomialis isolates collected from multiple medical centres in Taiwan.
A total of 57 A. nosocomialis isolates, including 46 TNAN and 11 tigecycline-susceptible A. nosocomialis (TSAN) isolates, were analysed. Of these, 46 TNAN isolates were clustered to ST410 (43 isolates) and ST68 (three isolates) by multi-locus sequence typing.
The relationship between the RND efflux pump and tigecycline resistance was indirectly verified by successfully reducing tigecycline resistance with NMP, an efflux pump inhibitor. The three RND efflux systems (AdeABC, AdeIJK and AdeFGH) were detected in all clinical isolates. The transcript level of adeB gene increased significantly and was correlated with tigecycline resistance. Moreover, the AdeRS two-component system was further classified into four different types of AdeRS patterns considering the amino acid sequence. Further analysis showed that tigecycline resistance was related to the transcript level of adeB gene and the AdeRS pattern.
This study showed that the dissemination of TNAN isolates in Taiwan is attributable mainly to the spread of ST410. The AdeABC efflux pump appeared to play an important role in the tigecycline resistance of A. nosocomialis.
已在临床分离株中发现不敏感替加环素的医院不动杆菌（TNAN）。 耐药-结节-分裂（RND）型外排系统在不敏感的鲍曼不动杆菌中对替加环素的耐药性起着重要作用，但在医院不动杆菌中的机制尚不清楚。我们的目的是分析从台湾多个医学中心收集的临床分离的医院不动杆菌中基于外排的替加环素耐药性的贡献。
共分析了 57 株医院不动杆菌分离株，包括 46 株 TNAN 和 11 株替加环素敏感的医院不动杆菌（TSAN）分离株。其中，46 株 TNAN 分离株通过多位点序列分型聚类为 ST410（43 株）和 ST68（3 株）。
成功用外排泵抑制剂 NMP 间接证实了 RND 外排泵与替加环素耐药性之间的关系，从而降低了替加环素的耐药性。所有临床分离株均检测到三种 RND 外排系统（AdeABC、AdeIJK 和 AdeFGH）。adeB 基因的转录水平显著增加，并与替加环素耐药性相关。此外，考虑到氨基酸序列，AdeRS 双组分系统进一步分为四种不同类型的 AdeRS 模式。进一步分析表明，替加环素耐药性与 adeB 基因转录水平和 AdeRS 模式有关。
本研究表明，台湾 TNAN 分离株的传播主要归因于 ST410 的传播。AdeABC 外排泵似乎在医院不动杆菌对替加环素的耐药性中起着重要作用。
