Ag Oxysalts™ Technology: Effectiveness Against Group C and G Streptococcus Infections

Dressings containing Ag Oxysalts™ Technology (Ag7NO11), which release silver ions at high oxidative states (Ag+ Ag2+ Ag3+), have demonstrated their ability to kill a broad spectrum of bacteria in both planktonic and biofilm forms (Thomason et al., 2018). With raising concerns over the effectiveness of silver wound dressings to treat streptococcus infections, a log reduction study was performed to determine the efficacy of Ag OxysaltsTM and singly ionic silver against both Group C and G streptococcus.

Samples of 3 silver gelling fiber dressings were inoculated with 1.2 x 106- 4.0x 106 cfu/ml of either streptococcus anginosus (group G) or streptococcus dysgalactiae subsp. equisimilis (group C). Samples were incubated at 30-35°C for 4 hours, 24 hours and 72 hours after which, samples were stomached and the silver neutralised. Serial dilutions were plated out on agar and incubated for 3 days at 30-35°C before colonies per plate were counted.

The dressing containing Ag Oxysalts™ Technology was the only dressing to significantly reduce both group C and G Streptococci after 4 hours, by showing a log reduction greater than 5. Only after 24 hours, did the singly ionic silver gelling fiber containing EDTA and benzethonium chloride significantly reduce bacterial load down to a similar level. It took 72 hours for the remaining singly ionic silver dressing to reduce bacterial load down to the same level as Ag Oxysalts™.

All three dressings tested showed antimicrobial efficacy against streptococcus infections in vitro despite having variations in their time to take effect. The dressing containing Ag OxysaltsTM had the greatest antimicrobial efficacy in the shortest time.

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References (if applicable): 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. https://doi.org/10.1111/wrr.12627