Department of Medical Microbiology, PGIMER, Chandigarh, India.
Department of Experimental Medicine and Biotechnology, PGIMER, Chandigarh, India.
Microb Pathog. 2017 Oct;111:218-224. doi: 10.1016/j.micpath.2017.08.048. Epub 2017 Sep 1.
Acinetobacter baumannii has emerged as an important opportunistic pathogen mostly causing nosocomial infections. The virulence factors of this important pathogen are largely unknown. Outer membrane vesicles (OMV) are naturally secreted by many gram negative and gram positive bacteria. These vesicles contain outer membrane proteins, lipids, periplasmic proteins, DNA and RNA. Their role in intracellular and intercellular signaling, transfer of virulence factors and eliciting immune response in host cells has been established in many pathogens. In this study, we investigated OMVs from three multi-drug resistant (MDR) clinical isolates and a non-MDR reference strain of A. baumannii for virulence potential. A. baumannii OMVs showed phospholipase C, hemolytic and leukotoxic activities. We found large variations in virulence potential between OMVs of MDR clinical isolates and non-MDR reference strain. These effector molecules were concentrated in OMVs than whole cell bacterial culture and cell-free supernatant. OMV-mediated phospholipase, hemolytic and leucotoxic activities may have a key role in pathogenicity of A. baumannii infection and may be future targets for therapeutic and preventive strategies. This is, to the best of our knowledge, the first report showing virulence potential of A. baumannii OMVs.
鲍曼不动杆菌已成为一种重要的机会性病原体，主要引起医院获得性感染。这种重要病原体的毒力因子在很大程度上尚不清楚。外膜囊泡（OMV）是许多革兰氏阴性和革兰氏阳性细菌自然分泌的。这些囊泡包含外膜蛋白、脂质、周质蛋白、DNA 和 RNA。它们在许多病原体的细胞内和细胞间信号转导、毒力因子转移和宿主细胞免疫应答中的作用已得到证实。在这项研究中，我们研究了三种多药耐药（MDR）临床分离株和一株非 MDR 参考株鲍曼不动杆菌的 OMV 以评估其毒力潜力。鲍曼不动杆菌 OMV 显示出磷脂酶 C、溶血和白细胞毒性活性。我们发现 MDR 临床分离株和非 MDR 参考株 OMV 的毒力潜力存在很大差异。这些效应分子在 OMV 中的浓度高于全细胞细菌培养物和无细胞上清液。OMV 介导的磷脂酶、溶血和白细胞毒性活性可能在鲍曼不动杆菌感染的致病性中起关键作用，并且可能成为治疗和预防策略的未来目标。据我们所知，这是首次报道鲍曼不动杆菌 OMV 的毒力潜力。
