The Observation of Staphylococcus aureus Invading Mature Rat Alveolar Osteoblasts

Objectives: To study whether Staphylococcus aureus (SA) can be internalized by cultured mature rat alveolar osteoblasts (MRAOBs), understand its abilities of invasion. Methods: MRAOBs were isolated from 4 to 8 week aged rats and tested for viability and purity prior to use. Staphylococcus aureus ATCC 25923 and MRAOBs were used and MRAOBs were infected at a multiplicity of infection (MOI) of 100:1(100 bacteria: 1 osteoblast) with SA for 15 to 60 min. Part of infected cells were sent for transmission electron microscope (TEM) examination and counted intracellular bacterium colony forming unit (CFU). Results: TEM showed SA were internalized at latter three time point with SA being ingested more at 60min and followed at 45min and 30min The mean ± SD CFU in one well of osteoblasts invasion of SA ATCC 25923 for 15, 30, 45 and 60 minutes was 13±5, 435±31, 803±95 and 1800±175 respectively. Conclusions: The results suggest that SA ATCC 25923 can be internalized by MRAOBs. Invasion level of bacteria bases on their invasion time.