Nanocrystalline Silver Dressing: Does Chloride in Physiological Fluid Inactivate its Anti-microbial Activity?

Beekman, J.1, Stelmach, M.2, Bishop, D.3, Wang, Y.4 Siarakas, S.5, Chong, E.6 Doble, P.7, Maitz, P.8, Li, Z9.

1 Burns Research, ANZAC Research Institute, Concord Repatriation General Hospital, Gate 3, Hospital Rd, Concord NSW 2139, joanneke.beekman@sydney.edu.au
2 Microbiology Dept, Concord Repatriation General Hospital, Hospital Rd, Concord NSW 2139, monicastelmach@hotmail.com
3 School of Mathematical and Physical Sciences, University of Technology, 745 Harris Street, Ultimo, NSW, 2007, david.bishop@uts.edu.au
4 Burns Research, ANZAC Research Institute, Concord Repatriation General Hospital, Gate 3, Hospital Rd, Concord NSW 2139, yiweiwang@anzac.edu.au
5 Microbiology Dept, Concord Repatriation General Hospital, Hospital Rd, Concord NSW 2139, steven.siarakas@sswahs.nsw.gov.au
6 Microbiology Dept, Concord Repatriation General Hospital, Hospital Rd, Concord NSW 2139
7 School of Mathematical and Physical Sciences, University of Technology, 745 Harris Street, Ultimo, NSW, 2007
8 Burns Unit & ANZAC Research Institute, Concord Repatriation General Hospital, Hospital Rd, Concord NSW 2139, peter.maitz@sydney.edu.au
9 Burns Unit & ANZAC Research Institute, Concord Repatriation General Hospital, Hospital Rd, Concord NSW 2139, zhe.li@sswahs.nsw.gov.au

Abstract
Background
Acticoat, a common nanocrystalline silver dressing, is used for managing burn wound infections. There has been a major concern that silver ions could react with anions such as chloride in body fluids and lose its antimicrobial activity.

Aims
To examine the impact of chloride on the activity of silver ions after moistening the dressing, mimicking clinical settings.

Material and Methods
Acticoat dressing discs were prepared and pre-treated in chloride-containing solutions before testing for silver release kinetics by inductively coupled plasma mass spectrometry and cytotoxicity in human dermal fibroblast culture. Anti-microbial activity was assessed using common bacterial strains in burn wound including Escherichia coli, Klebsiella pneumoniae (ESBL), Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa.

Results
No significant difference in cell viability was observed when fibroblasts were exposed to Acticoat pre-treated in water or saline. However, a pre-treatment in human or fetal bovine serum induced a significant decrease in cell viability after 24 and 72 hours compared to water treatment. In bacterial cultures, 24 hour saline-treated Acticoat showed some significant varying antimicrobial activity while serum-treated Acticoat showed a significant increase in activity compared to water-treated Acticoat. But Acticoat pre-treated in water for 72 hours was most effective among all groups in antimicrobial testings. Silver release kinetics are still being performed.

Conclusion
Generally, exposure to choride anions in saline or serum did not appear to inactivate Acticoat’s activity. The activity appears to be enhanced when exposed to a serum-rich environment, regardless of chloride anion presence by mechanisms to be further defined.

Key Words
Acticoat, nanocrystalline silver dressing, chloride, silver release kinetics, cytotoxicity, anti-microbial activity

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