In Vitro Activity of Silver-Bound Titanium Dioxide (TiAB) Against Multidrug-Resistant Vaginal Pathogens

Background: Gynecological infections, including bacterial vaginosis, vulvovaginal candidiasis, and recurrent urinary tract infections, represent a major clinical burden and are often complicated by biofilm formation and antimicrobial resistance. Novel non-antibiotic strategies are urgently needed. We previously demonstrated the antimicrobial activity of silver-bound titanium dioxide (TiAB) against multidrug-resistant bacteria isolated from dermatological infections. Objectives: We evaluated whether TiAB, at concentrations used in marketed medical devices, exerts antibacterial and antifungal effects against clinically relevant vaginal isolates by determining Minimum Inhibitory Concentration/ Minimum Bactericidal and Fungicidal Concentration (MIC, MBC/MFC), and time-kill kinetics. Methods: A total of 73 clinical isolates were collected from vaginal swabs, including Staphylococcus aureus (MSSA, MRSA), Escherichia coli (ESBL+ and non-ESBL), Klebsiella pneumoniae, Enterococcus spp., Streptococcus agalactiae, and Candida albicans. Minimum inhibitory concentrations (MICs) and minimum bactericidal/fungicidal concentrations (MBCs/MFCs) were determined by broth microdilution, and bactericidal activity was confirmed by time-kill assays. Results: TiAB exhibited potent activity against Gram-negative bacteria, with median MIC values of 1-2% (w/v) for E. coli and K. pneumoniae. Gram-positive isolates, including S. agalactiae and Enterococcus spp., showed higher MIC values (2-4%). Candida albicans displayed fungistatic inhibition at 4%. Time-kill assays confirmed rapid bactericidal effects for Gram-negative isolates within 8 h at 2× MIC, while Gram-positive bacteria required prolonged exposure. Conclusions: These findings extend previous evidence of TiAB's antimicrobial properties to gynecological pathogens, supporting its potential as a topical, non-antibiotic option for managing vaginal infections in an era of rising antimicrobial resistance. Further in vivo validation is warranted.