Comparative activity of silver-based antimicrobial composites for urinary catheters

• Published in: International journal of antimicrobial agents 2018-08, Vol.52 (2), p.166-171
• Main Authors: Thokala, Nikhil, Kealey, Dr Carmel, Kennedy, Dr James, Brady, Dr Damien B., Farrell, Dr Joseph
• Format: Article
• Language: English
• Subjects: Anti-Infective Agents - chemistry; Anti-Infective Agents - pharmacology; Antimicrobial efficacy; Diffusion; Drug Liberation; Elemental silver; Escherichia coli - drug effects; Escherichia coli - growth & development; Glass carrier; Humans; Ionic silver; Kinetics; Microbial Sensitivity Tests; Nylons - chemistry; Polymer/antimicrobial composites; Silver - chemistry; Silver - pharmacology; Silver ion release; Urinary Catheters
• ISSN: 0924-8579; 1872-7913
• DOI: 10.1016/j.ijantimicag.2018.03.015

•Elemental and ionic silver can be melt blended to prepare antimicrobial composites with long-term antibacterial activity.•Antibacterial properties of elemental silver are significantly higher in the broth dilution versus Kirby Bauer method.•Ion-release studies indicate elemental silver provides longer-term antibacterial activity compared with the ionic form.•Ions released over 84 days with elemental silver compared with 56 days with the ionic form. Biomedical polymers are an integral component in a wide range of medical devices because of their many desirable properties. However, extensive use of polymer materials in medical devices has been associated with an increasing incidence of patient infections. Efforts to address this issue have included incorporating antimicrobial additives to develop novel antimicrobial polymeric materials. Silver, with its high toxicity towards bacteria, oligodynamic effect and good thermal stability, has been employed as an additive for polymeric medical devices. In the present study, commercially available elemental (Biogate) and ionic (Ultrafresh 16) silver additives were incorporated into a Polyamide 11 (PA 11) matrix using a compression press. These polymer composites were evaluated for their antimicrobial and ion-release properties. Elemental silver composites were shown to retain their antimicrobial properties for extended periods and actively released silver ions for 84 days; whereas ionic silver composites lost their ion-release activity and, therefore, their antibacterial activity after 56 days. Bacterial log reduction units of 3.87 for ionic silver and 2.41 for elemental silver were identified within 24 h, when tested in accordance with the ISO 22196 test standard; this indicates that ionic silver is more efficient for short-term applications than elemental silver.