Patogenesi molecolare delle osteomieliti associate all'impianto

Impant-associated osteomyelitis is an infective process against bone tissue and it often leads to the destruction of the bone itself. The pathogenesis of impant-associated osteomyelitis is based on two fundamental concepts: internalization of pathogens into osteoblasts and bacterial ability to form biofilm. Both mechanisms allow to prevent bacterial elimination by host immune system and to block the action of majority antibiotics (that do not penetrate and have effect on intracellular bacteria) sustaining and feeding in this way the infection. The microplate-based assay allow to investigate the role of internalization mechanism in the pathogenesis of orthopaedic implant-infections caused by S. aureus, S. epidermidis, S. lugdunensis and E. faecalis. The study demonstrated the incompetence of S. epidermidis, S. lugdunensis and E. faecalis clinical isolates to invade MG-63 cells, on the opposite S. aureus invasion ability represents an optimal pathogenetic strategy for the pathogen to elude systemic therapy and host immune response. In addition here we investigate the role of innate immune response against bacterial biofilm. The interaction between S. epidermidis opsonized biofilm and PMN allowed to visualize the NETs. Neutrophil extracellular traps represent optimal weapon against bacterial biofilm because they wrap bacteria and so confine the infection. The understanding of internalization role in the pathogenesis of implant-associated osteomyelitis and the study of innate immune response against this kind of infection, often characterized by biofilm presence, are the basis to identify the best therapeutic strategy in order to eradicate the infection.