Ag Oxysalts™ Technology: Effectiveness Against Fungal Species

Polymicrobial wound infections are a significant cause of delayed healing. The majority of research into wound infections has focused on bacterial infections; however, molecular analysis has identified the presence of pathogenic fungi with poor healing (Kalen et al., 2016).  Furthermore, although the efficacy of antimicrobial dressings against bacteria is commonplace, there is limited testing against a broad-spectrum of fungi. Dressings containing Ag Oxysalts™ Technology (Ag7NO11) release silver ions at high oxidative states (Ag+ Ag2+ Ag3+). These are known to kill a broad-spectrum of bacteria in both planktonic and biofilm forms (Thomason et al., 2018) . With raising concerns over the clinical impact of fungal wound infections and the lack of evidence to show effectiveness of antimicrobial dressings to treat fungal infections, a log reduction study was performed to determine the efficacy of Ag OxysaltsTM against six fungal species.

Control or Ag OxysaltTM wound contact layer dressings were inoculated with 1.5 x 106- 5.0x 106 cfu/ml of either C. albicans, A. fumigatus, F. solani, C. herbarum, P.glabrum or T. ashaii. Samples were incubated at 30-35°C for 4 hours, 24 hours and 72 hours after which, samples were stomached and the silver neutralised. Remaining viable fungal counts were determined through serial dilutions which were plated onto agar and incubated for five days at 20-25°C.

The Ag Oxysalts™ dressing was effective against all six fungal species tested, showing a 2-5 log reduction within 4 hours and 3-6 log reduction within 72 hours. After 72 hours of Ag Oxysalts™ treatment, all fungal species had been reduced to the limit of detection of the experiment. This effect was achieved in only four hours for C.albicans and F.solani, with log reductions of greater than 5 and 4, respectively.

This study shows that Ag Oxysalts™ dressings are effective at reducing fungus by 99% to 99.999% after just four hours but continue to have strong sustained effects for at least 72 hours

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References (if applicable): Kalen, L., Loesche, M., Hodkinson, B. P., Heilmann, K., Ruthel, G., Gardner, S. E., Grice, E. A. (2016) Redefining the Chronic-Wound Microbiome: Fungal Communities Are Prevalent, Dynamic, and Associated with Delayed Healing. mBio 7.5: e01058-16.

Thomason, H. A., Lovett, J. M., Spina, C. J., Stephenson, C., Mcbain, A. J., & Hardman, M. J. (2018). Silver oxysalts promote cutaneous wound healing independent of infection. Wound Repair and Regeneration, 1–9.