Antiseptics' Concentration, Combination, and Exposure Time on Bacterial and Fungal Biofilm Eradication

Background: This study aims to assess the activity of solutions containing povidone-iodine (PI) and hydrogen peroxide (H₂O₂) alone or combined on the biofilm of microbial species in the contest of periprosthetic joint infection (PJI).

Methods: Different antiseptic solutions were tested on 2-day-old biofilms of Gram-positive and Gram-negative bacteria and fungi at 1 and 3 minutes of exposure. The efficacy of these solutions was evaluated by measuring the biofilm metabolic activity by methoxynitrosulfophenyl-tetrazolium carboxanilide (XTT) reduction assay. The anti-biofilm effect of 5% PI and 0.3% PI + 0.5% H₂O₂ was tested on a 5-day-old biofilm using colony-forming unit counts and an XTT reduction assay.

Results: PI and H₂O₂ solutions showed concentration-dependent anti-biofilm activity except for E. faecalis. PI at 5% was the most active solution against the 2-day-old biofilm of all test microorganisms. The 0.3% PI + 0.5% H₂O₂ solution had a significant effect only at 3 minutes. The 5% PI and 0.3% PI + 0.5% H₂O₂ effect was evaluated on 5-day-old biofilms. PI at 5% produced a significant reduction in metabolic activity at both 1 and 3 minutes; 0.3% PI + 0.5% H₂O₂ caused a significant activity against all Gram-positive strains after 3 minutes, with a greater metabolic activity reduction than 5% PI.

Conclusions: In the case of PJI caused by Gram-positive bacteria, 0.3% PI + 0.5% H₂O₂ could be used for wound irrigation for 3 minutes of exposure. In the case of PJI with a different etiological agent or PJI with an unknown etiology, it is advisable to use 5% PI for 1 minute of exposure.