IN VIVO VALIDATION OF A SEQUENTIAL ANTISEPTIC PROTOCOL FOR CHEMICAL DEBRIDEMENT IN A MURINE MODEL OF PERIPROSTHETIC JOINT INFECTION

Aim Periprosthetic joint infection (PJI) remains one of the most challenging complications in orthopaedic surgery due to the persistence of bacterial biofilms on implant surfaces. Chemical debridement is routinely used intraoperatively to disrupt these biofilms, yet the optimal antiseptic strategy is still undefined. Our group recently demonstrated in vitro that a sequential combination of 3% acetic acid (AA), 10% povidone-iodine (PI), and 5 mM hydrogen peroxide (H₂O₂), each applied for 3 minutes, achieved the highest anti-biofilm activity compared to single-agent protocols. This study aimed to validate these findings in vivo, assessing the efficacy and safety of this sequential chemical debridement (SCD) protocol in a murine model of Staphylococcus aureus PJI, and to compare it with commonly used antiseptic solutions. Method A 7-day mouse model of femoral PJI was established using S. aureus (ATCC29213) applied to surgical steel implants. Infected animals were treated with either SCD (3 min per agent), 10% PI alone (3 min), or wound lavage* solution (3 min). A sterile control group received saline irrigation. Post-treatment, implants were explanted for CFU quantification, local soft tissue was analyzed for cell viability, and intracardiac blood samples were cultured for 5 days to assess bacteremia. Results The SCD group demonstrated significantly lower bacterial counts with a median (IQR) log CFU/mL of 2.85 (0.00–3.72), compared to 4.02 (3.41–4.72) in the wound lavage* group (p = 0.02). A reduction was also observed versus PI alone (3.99 [1.11–4.33]), though not statistically significant (p = 0.29). The proportion of culture-negative implants was highest in the SCD group (40%), compared to 10% in PI and 0% in wound lavage*. Cell viability analysis showed comparable median (IQR) values across groups: 31.61% (23.80–55.06) for PI, 24.00% (16.18–37.37) for wound lavage*, and 31.93% (23.75–46.24) for SCD (p = 0.34), indicating no significant increase in cytotoxicity with SCD. Systemic dissemination, measured by positive blood cultures, occurred in 10% of SCD and wound lavage* animals, and in 30% of those treated with PI (p = 0.36). No bacteremia was detected in the control group. Conclusions Sequential application of AA, PI, and H₂O₂ significantly reduces bacterial burden in vivo compared to wound lavage*, without increasing local cytotoxicity or systemic spread. SCD shows promise as a novel anti-biofilm strategy for chemical debridement in PJI. These findings support further preclinical investigation and future clinical translation.