Silver carboxylate-doped titanium dioxide-polydimethylsiloxane coating decreases Cutibacterium acnes adherence and biofilm formation on polyether ether ketone.

Abstract Background Context Cutibacterium acnes (C. acnes) is a gram-positive facultative anaerobe found in the deep sebaceous follicles of the skin on the shoulder and back. C. acnes has been increasingly recognized as a pathogen in spinal surgical site infection (SSI) especially in the presence of instrumentation. Purpose This study assesses whether a silver carboxylate-doped titanium dioxide-polydimethylsiloxane (TiO2-PDMS) coating can decrease C. acnes adherence and biofilm formation on PEEK and four other commonly used spinal implant materials, Stainless Steel, Cobalt Chromium, Titanium, and Titanium Alloy. Study Design We compared the adherence of C. acnes over 24 hours between uncoated, 95:5 TiO2 to PDMS ratio with 10x silver carboxylate coating and a 100% silver carboxylate coating on each implant material, which were uniformly saw cut and sterilized. Implants were then subjected to scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). Methods Samples were coated using 95:5 TiO2-PDMS 10x silver carboxylate, 100% silver carboxylate, or left uncoated. C. acnes was applied onto the samples and allowed to adhere for periods of 4, 8, 12, 16, or 20 hours. Non-adherent bacteria were then washed from the samples. These samples were then allowed to continue incubating for a total of 24 hours. SEM and CLSM were used to visualize all samples for the presence of biofilm and quantification of C. acnes adherence at each time point. Results The 95:5 TiO2-PDMS 10x silver carboxylate coating was able to significantly decrease C. acnes adherence on PEEK after 8, 12, 16, and 20 hours of adherence. No statistical difference was found between the 95:5 TiO2-PDMS 10x silver carboxylate coating and the 100% silver carboxylate positive control. We previously observed extensive C. acnes biofilm formation on uncoated PEEK, but none on PEEK coated with either the 95:5 TiO2-PDMS 10x silver carboxylate or 100% Ag coating [1] . Furthermore, no biofilm formation was observed on Stainless Steel, Cobalt Chromium, Titanium, and Titanium Alloy coated with 95:5 TiO2-PDMS 10x silver carboxylate or 100% Ag coating. Conclusion A 95:5 TiO2-PDMS 10x silver carboxylate coating decreases C. acnes adhesion and prevents biofilm formation on PEEK and other common orthopedic implant materials. Clinical Significance A 95:5 TiO2-PDMS 10x silver carboxylate coating may help decrease spinal SSI due to C. acnes, especially in procedures with instrumentation.