Rapid broad-spectrum activity of molecular iodine against multidrug-resistant bacterial and fungal pathogens without residual staining.

Authors

Nandhana Nair, Arushi Sangal, Samuel Kim, Ilker Bayer, Victor Nizet, Elisabet Bjånes

Published in

Antimicrobial agents and chemotherapy. Pages e0076426. Sep 09, 2026. Epub Sep 09, 2026.

Abstract

Povidone iodine (PVP-I) is a widely used topical antiseptic with broad antimicrobial activity, but its clinical utility can be limited by skin irritation, slow drying, and persistent staining of skin, textiles, and surfaces. Here, we evaluated reformulated molecular iodine (I₂) products as potential non-staining alternatives with retained or enhanced antimicrobial efficacy. Three I₂ formulations (soak, nasal antiseptic, and hand ointment) were tested against 17 clinically relevant bacterial and fungal pathogens, including multidrug-resistant organisms and emerging nosocomial pathogens. Antimicrobial performance was assessed by quantitative kill assays, textile staining studies, and persistence testing on dried surfaces. All three I₂ formulations demonstrated broad-spectrum activity against all organisms tested, with rapid 3-4 log₁₀ reduction in colony-forming units (CFUs) or >99.9% killing commonly achieved within 15 s; selected fungal species required longer contact times or higher concentrations for maximal activity. Potent activity was observed against major healthcare-associated bacterial pathogens, including Staphylococcus aureus, Enterococcus faecalis, Klebsiella pneumoniae, and Pseudomonas aeruginosa, as well as fungal pathogens including Candida albicans and Candidozyma auris. Compared with PVP-I, I₂ exhibited minimal residual staining and was readily removed from porous hospital textiles after brief water rinsing. Surface persistence studies further demonstrated sustained antimicrobial activity after drying. These findings indicate that I₂ retains the broad-spectrum efficacy of traditional iodophors while offering practical advantages in material compatibility and reduced residual staining. I₂ formulations may, therefore, represent useful alternatives for topical antisepsis and environmental decontamination in high-throughput healthcare settings where both antimicrobial performance and staining-related costs are important considerations.

PMID:
42714451
Bibliographic data and abstract were imported from PubMed on 09 Sep 2026.

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