Cathodic voltage-controlled electrical stimulation of titanium implants as treatment for methicillin-resistant Staphylococcus aureus periprosthetic infections

Effective treatment options are often limited for implant-associated orthopedic infections. In this study we evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) of -1.8V (vs. Ag/AgCl) to commercially pure titanium (cpTi) substrates with preformed biofilm-like structures of methicillin-resistant Staphylococcus aureus (MRSA). The invitro studies showed that as compared to the open circuit potential (OCP) conditions, CVCES of -1.8V for 1hsignificantly reduced the colony-forming units (CFU) of MRSA enumerated from the cpTi by 97% (1.89×106 vs 6.45×104CFU/ml) and from the surrounding solution by 92% (6.63×105 vs. 5.15×104CFU/ml). The invivo studies, utilizing a rodent periprosthetic infection model, showed that as compared to the OCP conditions, CVCES at -1.8V for 1hsignificantly reduced MRSA CFUs in the bone tissue by 87% (1.15×105 vs. 1.48×104CFU/ml) and reduced CFU on the cpTi implant by 98% (5.48×104 vs 1.16×103CFU/ml). The stimulation was not associated with histological changes in the host tissue surrounding the implant. As compared to the OCP conditions, the-1.8V stimulation significantly increased the interfacial capacitance (18.93 vs. 98.25μF/cm²) and decreased polarization resistance (868,250 vs. 108Ω-cm²) of the cpTi. The antimicrobial effects are thought to be associated with these voltage-dependent electrochemical surface properties of the cpTi.