Faculty of Science, Department of Biology, University of Zagreb, Zagreb, Croatia E-mail:
Laboratory for Microscopy & Microanalysis, University of Pretoria, Pretoria, South Africa.
Water Sci Technol. 2019 Oct;80(8):1581-1590. doi: 10.2166/wst.2019.408.
Bacterium Acinetobacter baumannii is a leading cause of hospital infections. Over the last decade, its occurrence in natural environments outside hospital settings has been reported. The aim was to examine the survival of A. baumannii in water media exposed to different ranges of oxygen supply in order to predict its behaviour in the environment. The abundance of five A. baumannii isolates was monitored in nutrient-depleted and nutrient-rich water media in aerated, intermediate and anaerobic conditions (oxygen saturation 96, 56 and 0%, respectively). A. baumannii survived in both media in all tested oxygen concentrations for 50 days. In nutrient-rich water survival of A. baumannii was lowest in anaerobic conditions, while in nutrient-depleted water there was no difference in survival regardless of oxygen availability. A. baumannii formed translucent small colony variants as the fast response (after 1 day) and dormant cells as the prolonged response (after 14 days) to anaerobic conditions. Transmission electron microscopy (TEM) images showed the outer membrane of coccobacillus dormant cells was up to four times thicker than in regular cells. Once in the environment, A. baumannii is able to survive regardless of the availability of dissolved oxygen, which represents a serious public health concern.
鲍曼不动杆菌是医院感染的主要病原体。近十年来，已有报道称其在医院环境以外的自然环境中存在。本研究旨在研究暴露于不同氧气供应范围的水介质中鲍曼不动杆菌的存活情况，以便预测其在环境中的行为。在充气、中间和厌氧条件（氧气饱和度分别为 96%、56%和 0%）下，监测了营养耗尽和营养丰富的水介质中 5 种鲍曼不动杆菌分离株的丰度。鲍曼不动杆菌在 50 天内的所有测试氧气浓度下均能在两种介质中存活。在营养丰富的水中，鲍曼不动杆菌在厌氧条件下的存活率最低，而在营养耗尽的水中，无论氧气是否存在，存活率均无差异。鲍曼不动杆菌形成半透明的小菌落变体作为快速反应（1 天后）和休眠细胞作为延长反应（14 天后）对厌氧条件的反应。透射电子显微镜（TEM）图像显示，休眠细胞的外膜比普通细胞厚 4 倍。一旦进入环境，鲍曼不动杆菌能够在无论是否存在溶解氧的情况下存活，这是一个严重的公共卫生问题。
