Intracellular Staphylococcus aureus induces apoptosis in mouse osteoblasts

Staphylococcus aureus invades osteoblasts and is the primary cause of osteo myelitis. This study examined the ability of S. aureus to induce apoptosis in a mouse osteoblast cell line. The presence of intracellular S. aureus wa s demonstrated by transmission electron microscopy. Light microscopy was ut ilized to examine morphological changes in the osteoblasts following killin g of extracellular bacteria. Cell rounding was observed, and dark centers d ue to condensation of chromatin were noted in cells in infected osteoblast cultures. DNA was isolated From infected osteoblast cultures, and electroph oresis revealed the laddering effect characteristic of cells undergoing apo ptosis. Additionally, an in situ cell death detection assay was utilized to label apoptosis-induced DNA strand breaks. Apoptotic nuclei were present, providing further evidence that S, aureus induces apoptosis in osteoblasts. (C) 2000 Federation of European Microbiological Societies. Published by El sevier Science B.V. All rights reserved.