Efficacy of Dilute Povidone-Iodine against Multi-Drug Resistant Bacterial Biofilms, Fungal Biofilms and Fungal Spores

Objective: To study the in vitro effect of novel low-dose povidoneiodine formulations against established biofilms of multi-drug resistant Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans and to test the Minimal Inhibitory Concentration of the same formulations against Candida auris, Trichophton mentagrophytes, Microsporum canis, Candida albicans and Aspergillus fumigatus. Methods: Biofilms of multi-drug resistant Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans were developed on solid surfaces using the Calgary Biofilm Device plate. Minimum biofilm eradication concentration was then determined for each test drug and for control samples of known antimicrobials, ciprofloxacin and itraconazole. Quality control fungal strains of Candida auris, Trichophton mentagrophytes, Microsporum canis, Candida albicans and Aspergillus fumigatus were grown on Sabouraud’s Dextrose Agar plates as the growth medium for the anti-fungal susceptibility. Minimal Inhibitory Concentration was then determined for each test drug and for control samples of know antifungals, fluconazole and amphotericin B. Results: The low-dose povidone-iodine formulations completely eliminated all biofilms of bacterial and fungal species in the test systems. Ciprofloxacin was able to eradicate one bacterial biofilm only at concentrations greater than 0.25 ug/mL. Fluconazole was ineffective against C. albicans, A. fumigatus and C. auris. Amphotericin B had good anti-fungal activity against fungal strains. Conclusions: These novel dilute PVP-I formulations are effective anti-biofilm and anti-fungal /sporicidal agents in vitro. Further evaluation in living models is warranted.