Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany.
Environ Microbiol. 2020 Apr;22(4):1370-1380. doi: 10.1111/1462-2920.14951. Epub 2020 Feb 29.
The opportunistic human pathogen Acinetobacter baumannii is one of the leading causes of nosocomial infections. The high prevalence of multidrug-resistant strains, a high adaptability to changing environments and an overall pronounced stress resistance contribute to persistence and spread of the bacteria in hospitals and thereby promote repeated outbreaks. Altogether, the success of A. baumannii is mainly built on adaptation and stress resistance mechanisms, rather than relying on 'true' virulence factors. One of the stress factors that pathogens must cope with is osmolarity, which can differ between the external environment and different body parts of the human host. A. baumannii ATCC 19606 accumulates the compatible solutes glutamate, mannitol and trehalose in response to high salinities. In this work, it was found that most of the solutes vanish immediately after reaching stationary phase, a very unusual phenomenon. While glutamate can be metabolized, mannitol produced by MtlD is excreted to the medium in high amounts. First results indicate that A. baumannii ATCC 19606 undergoes a rapid switch to a dormant state (viable but non-culturable) after disappearance of the compatible solutes. Resuscitation from this state could easily be achieved in PBS or fresh medium.
机会性病原体鲍曼不动杆菌是医院获得性感染的主要病原体之一。其多重耐药菌株的高流行率、对环境变化的高适应性以及整体明显的抗应激能力，导致其在医院中的持续存在和传播，并促进了反复爆发。总的来说，鲍曼不动杆菌的成功主要建立在适应和抗应激机制上，而不是依赖于“真正的”毒力因子。病原体必须应对的应激因素之一是渗透压，它可以在外部环境和人体宿主的不同部位之间有所不同。鲍曼不动杆菌 ATCC 19606 会积累谷氨酸、甘露醇和海藻糖等相容性溶质，以应对高盐度环境。在这项工作中，人们发现大多数溶质在达到稳定期后会立即消失，这是一种非常不寻常的现象。虽然谷氨酸可以被代谢，但 MtlD 产生的甘露醇会以大量形式被排泄到培养基中。初步结果表明，在相容性溶质消失后，鲍曼不动杆菌 ATCC 19606 会迅速进入休眠状态（存活但不可培养）。在 PBS 或新鲜培养基中很容易从这种状态复苏。
