Intracellular Staphylococcus aureus. A mechanism for the indolence of osteomyelitis

Area of Science:

• Microbiology
• Cell Biology
• Orthopedics

Background:

• Staphylococcus aureus is a primary cause of human osteomyelitis.
• This bacterium invades and persists within osteoblasts.
• The fate of intracellular bacteria after host cell death is unknown.

Purpose of the Study:

• To investigate the viability and infectivity of Staphylococcus aureus released from dead or dying osteoblasts.
• To understand the intracellular survival and release mechanism of Staph. aureus in osteomyelitis.

Main Methods:

• Human osteoblasts were infected with Staph. aureus.
• Osteoblasts were subsequently lysed or trypsinized to release intracellular bacteria.
• Released bacteria were cultured, quantified, and used to infect new osteoblast cultures.

Main Results:

• Equivalent numbers of Staph. aureus were recovered using both lysis and trypsinization methods.
• Staph. aureus recovered from infected osteoblasts (at time zero and 24 hours) could successfully invade a second osteoblast culture.
• These findings demonstrate the viability and reinfectivity of bacteria released from dead osteoblasts.

Conclusions:

• Dead or dying osteoblasts release viable Staphylococcus aureus.
• Staph. aureus released from compromised osteoblasts can re-initiate infection in new host cells.
• This mechanism may play a significant role in the persistence and recurrence of osteomyelitis.