Efficacy of Commercially Available Irrigation Solutions on Removal of Staphylococcus Aureus and Biofilm From Porous Titanium Implants: An In Vitro Study.

BACKGROUND

Periprosthetic joint infection remains a major problem. The bactericidal efficacy of commercial irrigation solutions for the treatment of infection is not well established in the presence of porous titanium (Ti) implants. This study compared the in vitro efficacy of five irrigation solutions on infected three-dimensional-printed porous Ti discs.

METHODS

Titanium discs (2 × 4 mm, 400, 700, and 1,000 μm) were infected with S. aureus (1 × 10 colony-forming unit/mL) and incubated for 3 hours or 3 days to create acute or chronic infection with biofilm. Discs were irrigated with saline, antibiotic, or antiseptic solutions, then repeatedly sonicated. Sonicates were cultured for bacterial quantification. Statistical analyses were performed using one-way analysis of variance (ANOVA), followed by Tukey-Kramer post hoc testing (P < .05 significance). Biofilms were visualized by scanning electron microscopy.

RESULTS

Saline irrigation was ineffective in both groups. In acute infections with 400 μm pores, differences were found with saline versus solution #3 (P = .015) and #4 (P = .015). Solution #4 had the lowest bacterial counts for all pore sizes. For biofilm, irrigation with saline, solutions #1, #2, and #3 inadequately cleared bacteria in all pore sizes. Lower remaining concentrations were observed in #4 with 400μm pores compared to saline (P = .06) and #2 (P = .039). The scanning electron microscopy showed a reduction of biofilm in samples washed with #4.

CONCLUSIONS

Irrigation of infected porous Ti discs with saline, solutions #1 and #2 failed to reduce the bacterial load. The 400 μm discs consistently had more bacteria despite irrigation, highlighting the difficulty of removing bacteria from small pores. Solutions #3 and #4 reduced bacteria acutely, but only #4 demonstrated efficacy in clearing biofilm compared to saline. These results should be considered when treating periprosthetic joint infection in the presence of porous components and the potential presence of biofilm.