POLYHEXANIDE COMBINED WITH MECHANICAL OR ULTRASONIC DISRUPTION ENABLES RAPID ERADICATION OF IMPLANT-ASSOCIATED BIOFILMS

Background Successful debridement, antibiotics, and implant retention (DAIR) requires near-complete removal of biofilm from retained implant components to prevent bacterial persistence and infection recurrence. This study evaluated polyhexanide (PHMB) alone and in combination with mechanical and ultrasonic disruption for implant-associated biofilms. Materials and Methods Immature biofilms of Staphylococcus epidermidis (ATCC 35984) and Escherichia coli (ATCC 25922) were grown on Ti-6Al-4V, CoCrMo, and polyethylene (PE) discs. PHMB concentration screening (0.0004–0.04%) identified sub-eradicative but strongly inhibitory conditions for combination testing. In the main experiments, PHMB was applied at species- and material-specific concentrations (0.004% on metals; 0.04% on PE for S. epidermidis; 0.004% for E. coli). Biofilms were exposed for 1 minute to PHMB alone or combined with sonication, mechanical toothbrushing, or ultrasonic toothbrushing. Biofilm removal was quantified by CFU from detached fractions, and residual metabolic activity was assessed by isothermal microcalorimetry (IMC). Results PHMB at 0.02–0.04% suppressed metabolic activity of both species on Ti-6Al-4V and CoCrMo, and of E. coli on PE, while S. epidermidis on PE showed only partial suppression, guiding concentration selection for main experiments. All single-modality treatments reduced biofilm metabolic activity but did not achieve complete suppression. No CFU were recovered from PHMB-treated samples, likely due to carryover during sampling of the detached fraction. In contrast, PHMB combined with sonication, mechanical brushing, or ultrasonic brushing achieved complete suppression of biofilm metabolic activity across all materials and both species within 1 minute. Conclusion PHMB combined with mechanical or ultrasonic disruption enables rapid and complete eradication of implant-associated biofilms. Among the evaluated approaches, the ultrasonic brushing system represents a readily translatable, clinically applicable device for intraoperative biofilm management. This strategy achieves consistent biofilm eradication within one minute across materials and bacterial species, supporting its potential role in DAIR procedures.