Orthopedic implant infections: Incompetence of Staphylococcus epidermidis, Staphylococcus lugdunensis, and...

Area of Science:

• Biomedical Engineering
• Infectious Diseases
• Microbiology

Background:

• Septic failure is a major complication of prosthetic implants, often caused by bacteria that enter host cells.
• Staphylococcus aureus, a leading cause of orthopedic implant infections, invades bone cells, leading to osteomyelitis.
• Other common implant pathogens include Staphylococcus epidermidis, Staphylococcus lugdunensis, and Enterococcus faecalis.

Purpose of the Study:

• To investigate the internalization ability of clinical isolates of S. epidermidis, S. lugdunensis, and E. faecalis into osteoblastic MG63 cells.
• To determine if osteoblast invasion is a pathogenic mechanism for these bacteria in orthopedic implant infections.

Main Methods:

• Collected clinical isolates of S. epidermidis (22), S. lugdunensis (9), and E. faecalis (21) from orthopedic implant infections.
• Categorized isolates into clusters using ribotyping.
• Quantified bacterial internalization into MG63 cells using a microtiter plate-based assay.

Main Results:

• S. epidermidis, S. lugdunensis, and E. faecalis strains showed negligible internalization into MG63 osteoblast cells.
• Internalization rates were approximately three orders of magnitude lower than that of Staphylococcus aureus.
• Osteoblast invasion is not a significant pathogenic mechanism for these three bacterial species in orthopedic implant infections.

Conclusions:

• Osteoblast invasion is not a key pathogenic mechanism for S. epidermidis, S. lugdunensis, and E. faecalis in orthopedic implant infections.
• Intracellularly active antimicrobials are likely not required for treating infections caused by these specific bacteria.
• Findings have implications for understanding bacterial interactions with biomaterials and host cells.