Interactions among osteoblastic cells, Staphylococcus aureus, and chitosan-immobilized titanium implants in a postoperative coculture system: An in vitro study.

Biomaterial-related infections (BRIs) have become a major challenge in the field of orthopedic implants. In this study, we delved into the problem of BRI and attempted to reduce the possibility of BRI incidence via surface modification of titanium (Ti) with chitosan (SA-CS-Ti). To comprehensively evaluate the anti-infection potential of SA-CS-Ti, we first constructed a postoperative infection (POI) model with varying concentrations of bacteria (102  CFU/sample and 104  CFU/sample) and a constant number of SaOS-2 cells (105 /sample). Then, we biologically characterized the interactions between the SaOS-2 cells, bacteria, and different Ti implants using the POI model. The results from the osteoblastic cell and bacterial attachment tests demonstrated that the SA-CS-Ti surfaces exhibit superior osteogenic behavior relative to other Ti surfaces studied while showing significant anti-infective activities in the POI model with a low infection ratio (bacteria: cell ratio of 0.001:1) 30 min after infection. Additionally, the SA-CS-Ti surfaces showed significantly reduced (p < 0.05) bacteria proliferation compared to the control Ti surfaces (UN-Ti), demonstrating their antifouling property. The significantly increased (p < 0.05) sensitivity of Staphylococcus. aureus adhered to the SA-CS-Ti surfaces against cefazolin (1 mg/L treatment) and gentamicin (10 mg/L and 100 mg/L treatment) in the coculture system augmented potential of SA-CS-Ti to be used as orthopedic implants.