Apoptotic cell death induced by Acinetobacter baumannii in epithelial cells through caspase-3 activation

Epithelial cell death induced by Acinetobacter baumannii infection was inve stigated using in vitro assays. Eight hours after live A. baumannii infecti on, HeLa cells exhibited detachment from the dish, rounding morphologies, h igh proportions of trypan blue-positive cells and extensive DNA breakdown w ith faint apoptotic banding, which is indicative of cells undergoing apopto sis. The enzymatic activity of caspase-3 was increased in cells as early as 2 h after infection. In addition, apoptosis of HeLa cells was induced by t reatment with bacterial culture filtrates but not with formalin-killed bact eria. These results indicate that A. baumannii infection triggers apoptosis in HeLa cells through caspase-3 activation.