Tobin Liam A, Lam Margaret M C, Hamidian Mehrad
Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia.
Department of Infectious Diseases, School of Translational Medicine, Monash University, Melbourne, VIC, Australia.
NPJ Antimicrob Resist. 2025 Jul 22;3(1):65. doi: 10.1038/s44259-025-00133-z.
Plasmids play a central role in horizontal gene transfer and bacterial adaptation, especially in the context of antimicrobial resistance (AMR) among opportunistic pathogens. Some members of the genus Acinetobacter are known for their role in hospital-acquired infections, harboring plasmids that facilitate rapid adaptation to selective pressures. However, the extent of plasmid diversity and evolutionary dynamics within Acinetobacter has not been fully elucidated. In this study, we analysed 1846 complete and non-redundant Acinetobacter plasmid sequences, identifying 166 novel Replicase (Rep) protein types and providing a significant update to the Acinetobacter Plasmid Typing (APT) scheme, which now comprises 257 Rep types. A detailed phylogenetic analysis of the prevailing R3-type Rep sequences reveals two distinct evolutionary clades (A and B) and several additional subclades. This phylogenetic structure suggests evolutionary pressures within all clades, potentially influenced by host species distribution and environmental factors. Analysis of these plasmids highlights diverse plasmid types involved in dissemination of AMR within the genus in different niches, underscoring both clinical and natural environments as reservoirs of Acinetobacter plasmids. Our findings provide a refined framework for tracking Acinetobacter plasmids, advancing our understanding of plasmid-mediated AMR spread and informing strategies to combat the spread of AMR in this critical genus.
质粒在水平基因转移和细菌适应性中发挥着核心作用，尤其是在机会性病原体的抗菌耐药性（AMR）背景下。不动杆菌属的一些成员因其在医院获得性感染中的作用而闻名，它们携带的质粒有助于快速适应选择压力。然而，不动杆菌属内质粒多样性和进化动态的程度尚未完全阐明。在本研究中，我们分析了1846个完整且无冗余的不动杆菌质粒序列，鉴定出166种新型复制酶（Rep）蛋白类型，并对不动杆菌质粒分型（APT）方案进行了重大更新，该方案现在包含257种Rep类型。对主要的R3型Rep序列进行的详细系统发育分析揭示了两个不同的进化分支（A和B）以及几个额外的亚分支。这种系统发育结构表明所有分支内都存在进化压力，可能受到宿主物种分布和环境因素的影响。对这些质粒的分析突出了在不同生态位中参与不动杆菌属内AMR传播的多种质粒类型，强调临床和自然环境都是不动杆菌质粒的储存库。我们的研究结果为追踪不动杆菌质粒提供了一个完善的框架，增进了我们对质粒介导的AMR传播的理解，并为对抗这一关键菌属中AMR传播的策略提供了信息。
