Polymicrobial periprosthetic joint infection: eradication with different antimicrobials

Antibiotics incorporated into spacers do not guarantee complete eradication of infection. This study aimed to compare, <i>in vitro</i>, the antimicrobial activity of antibiotic-loaded cement with and without additional alternative antimicrobial molecules for the eradication of polymicrobial biofilms. Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), <i>Pseudomonas aeruginosa</i> (PA), and <i>Candida albicans</i> (CA) were selected to form mono- and polymicrobial biofilms on polyurethane sponges. Bone cement was supplemented with vancomycin, imipenem, silver nitrate (SN), and xylitol in different combinations. In monomicrobial biofilms, the combination of vancomycin + SN + xylitol showed superior activity against MRSA compared with other formulations. In polymicrobial biofilms, the combinations imipenem + vancomycin + xylitol, imipenem + vancomycin + SN, and imipenem + vancomycin + SN + xylitol were most effective in eradicating PA. For MRSA, all combinations achieved complete eradication, whereas CA eradication remained incomplete. Overall, the inclusion of SN and xylitol in cement improved antimicrobial performance compared with antibiotic-only formulations.