Protromic and functional study of Acinetobacter abumannii outer membrane vesicles

Acinetobacter baumannii, a gram-negative aerobic bacterium, is one of the most spread bacteria which can be easily isolated from water, soil, and hospital facilities. It may cause various types of diseases such as respiratory tract infection, urinary tract infection, nosocomial pneumonia and bacteremia. It was noticed that A. baumanii was existed in the blood stream of military people deployed in Iraq and Afghanistan who suffered with serious injury. The treatment for the infection of A. baumannii is limited because it resists to resist nearly 90% of antibiotics. Therefore, to better treat the infection of A. baumannii,the mechanism of infection and virulence factors involved in pathogenecity needed to be studied. Similar to other gram-negative bacteria, outer membrane vesicles (OMVs) secreted by A. baumannii consisted of virulence factors. In my study, the A. baumannii OMVs were isolated and observed under transmission electron microscopy. The proteomic analysis indicated that A. baumannii OMVs consisted of various virulence factors such as OmpA. To understand the function of the A. baumannii OMVs, OMVs were incubated with macrophage cells. Results showed the macrophage cells were lysed when incubated with OMVs compared to cells in the control group which were intact. The quantification of cytotoxicity caused by OMVs showed that the mortality rate reached 80% when 0.02 ug/ml OMVs were added.

In my study, the OMVs were isolated and observed. The virulence factors were identified by proteomic analysis and OMVs are toxic to macrophage cells in vitro.