Inhibition of biofilm formation on iodine-supported titanium implants.

PURPOSE: We have developed iodine-supported titanium implants that suppress microbial activities and conducted in vivo and in vitro studies to determine their antimicrobial properties.

METHODS: The implants were Ti-6Al-4 V titanium implants either untreated (Ti), treated with oxide film on the Ti surface by anodization (Ti-O), or treated with an iodine coating on oxidation film (Ti-I). The strain of bacteria used in this study was Gram-positive Staphylococcus aureus strain ATCC 25923. We analyzed the antibacterial attachment effects in vivo by using rats. The attachment bacteria on the implant surface were evaluated using a spread-plate method assay. A biofilm study was performed in vitro. The biofilm formed after bacterial attachment was qualitatively studied with fluorescence microscopy (FM) and scanning electron microscopy (SEM). Also, the formed biofilm was quantitatively studied with a spread-plate method assay.

RESULTS: In vivo analysis of antimicrobial attachment effects showed that the mean viable bacterial number was significantly lower on Ti-I than Ti or Ti-O surfaces. In the in vitro biofilm study, FM and SEM images showed thick and mature biofilm formation on Ti and Ti-O and thin, small biofilm formation on Ti-I. A quantitative biofilm analysis found a significant difference in the number of viable bacteria between Ti-I and Ti or Ti-O.

CONCLUSIONS: This study showed that iodine-supported implants have a good antibacterial attachment effect and inhibit biofilm formation and growth. Iodine-supported implants may have great potential as innovative antibacterial implants that can prevent implant related infection in orthopaedic surgery.