Topical adjuvants incompletely remove adherent Staphylococcus aureus from implant materials

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Adjuvant treatments including Betadine, Dakin’s solution (sodium hypochlorite), or hydrogen peroxide (H2O2) have been attempted to eradicate prosthetic joint infection caused by biofilm or intracellular bacteria. The purpose of this study was to evaluate the in vitro abilities of chemical adjuvants to decrease Staphylococcus aureus (S. aureus) biofilm presence on orthopaedic implant grade materials, including titanium, stainless steel, and cobalt chrome. S. aureus biofilms were grown for 48 h and evaluated for baseline colony forming units/centimeter squared (CFU/cm2) and compared to treatments with Betadine, Dakin’s solution, H2O2, or 1% chlorine dioxide (ClO2). Control discs (n = 18) across all metals had an average of 4.2 × 107 CFU/cm2. All treatments had statistically significant reductions in CFU/cm2 when compared to respective control discs (p <0.05). For all metals combined, the most efficacious treatments were Betadine and H2O2, with an average 98% and 97% CFU/cm2 reduction, respectively. There were no significant differences between reductions seen with Betadine and H2O2, but both groups had statistically greater reductions than Dakin’s solution and ClO2. There was no change in antibiotic resistance patterns after treatment. Analysis of S. aureus biofilms demonstrated a statistically significant reduction in biofilm after a five-minute treatment with the modalities, with an average two log reduction in CFU/cm2. Statement of clinical significance: While statistically significant reductions in CFU/cm2 were accomplished with chemical adjuvant treatments, the overall concentration of bacteria never fell below 105 CFU/cm2, leading to questionable clinical significance. Further techniques to eradicate biofilm should be investigated.