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Polymicrobial infection requires higher concentration of irrigation solution than monomicrobial infection to
Daniyil Semeshchenko1, Alicia Farinati2, Iván Huespe3
1'Sir John Charnley' Hip Surgery Unit, Institute of Orthopaedics 'Carlos E. Ottolenghi', Italian Hospital of Buenos Aires, 4190 Perón St., Buenos Aires, Argentina; IMCS, Institute of Medical and Health Sciences Research, Department of Microbiology, Faculty of Medicine, Universidad del Salvador, Buenos Aires, Argentina.
Background:
Polymicrobial periprosthetic joint infection (PJI) is associated with poor outcomes after debridement, antibiotics, and implant retention (DAIR). Although irrigation is a critical component of DAIR, the concentrations required to eradicate polymicrobial biofilms remain unclear.
Aim:
The aim of this study was to evaluate the in-vitro efficacy of four antiseptic irrigation solutions against monomicrobial and polymicrobial biofilms formed on clinically relevant titanium implant surfaces.
Methods:
Biofilms of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were grown on Ti-6Al-4V screw-hole covers. Povidone iodine (PI), acetic acid (AA), Granudacyn®, and chlorhexidine were tested. Minimal inhibitory, bactericidal, and biofilm eradication concentrations (minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBS), minimum biofilm eradication concentration [MBEC]) were determined. A 3-min irrigation assay assessed concentrations achieving ≥99.9% biofilm reduction in monomicrobial and polymicrobial models.
Findings:
PI demonstrated the greatest relative effectiveness in eradicating both monomicrobial and polymicrobial biofilms among the tested irrigation solutions. AA and chlorhexidine required substantially higher concentrations than their respective MBEC to achieve 99.9% biofilm eradication, whereas Granudacyn showed limited activity and failed to achieve complete eradication in either condition. Higher irrigation solution concentrations were consistently required to eradicate polymicrobial biofilms than monomicrobial biofilms across all agents. In particular, PI and AA required two- to four-fold higher concentrations, and chlorhexidine required approximately 10-fold higher concentrations, for polymicrobial biofilm eradication.
Conclusions:
Polymicrobial biofilms demonstrate significantly increased tolerance to antiseptic irrigation compared with monomicrobial biofilms. Irrigation strategies effective against single-species infections may be inadequate in polymicrobial PJI, supporting the need for higher-concentration or optimized antiseptic protocols during DAIR.
Insights
Polymicrobial biofilms in periprosthetic joint infections (PJI) are more resistant to antiseptic irrigation than single-species biofilms. Higher concentrations of irrigation solutions are needed to effectively eradicate polymicrobial biofilms during debridement, antibiotics, and implant retention (DAIR).
Area of Science:
- Microbiology
- Biomaterials Science
- Infectious Diseases
Background:
- Polymicrobial periprosthetic joint infection (PJI) leads to poor outcomes following debridement, antibiotics, and implant retention (DAIR).
- The optimal antiseptic concentrations for eradicating polymicrobial biofilms during DAIR remain undetermined.
Purpose of the Study:
- To assess the in vitro effectiveness of four antiseptic irrigation solutions against mono- and polymicrobial biofilms.
- To evaluate biofilm eradication on clinically relevant titanium implant surfaces.
Main Methods:
- Biofilms of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were cultivated on Ti-6Al-4V implant materials.
- Povidone iodine (PI), acetic acid (AA), Granudacyn®, and chlorhexidine efficacy was determined by minimal inhibitory, bactericidal, and biofilm eradication concentrations (MIC, MBC, MBEC).
- A 3-minute irrigation assay evaluated concentrations achieving ≥99.9% biofilm reduction in both monomicrobial and polymicrobial models.
Main Results:
- Povidone iodine (PI) exhibited the highest efficacy in eradicating both monomicrobial and polymicrobial biofilms.
- Acetic acid (AA) and chlorhexidine required significantly higher concentrations than their MBEC for 99.9% biofilm eradication.
- Polymicrobial biofilms consistently required higher irrigation concentrations (2-4x for PI/AA, ~10x for chlorhexidine) for eradication compared to monomicrobial biofilms.
Conclusions:
- Polymicrobial biofilms exhibit significantly greater tolerance to antiseptic irrigation than monomicrobial biofilms.
- Current irrigation protocols effective for single-species PJI may be insufficient for polymicrobial PJI.
- Optimized or higher-concentration antiseptic protocols are necessary for effective DAIR in polymicrobial PJI.
