Challenging silver: a comparison of in vitro testing methods

2018, Vol 9, No 2, pages 35–42

There is no current British Standard for testing the antimicrobial efficacy of dressings. Several other methods have been devised by microbiologists to demonstrate efficacy of the antimicrobial agent.  In this study, three methods – transmission, translocation and challenge testing – were used to assess the antimicrobial efficacy of seven silver dressings. Four dressings were tested alongside their non-silver counterpart and all were tested with gauze as a control. The performance of the antimicrobial within the dressing varied depending upon the method used, the organism and the control chosen to calculate the log reduction in the challenge test. Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli showed greater susceptibility to silver than Gram-positive Staphylococcus aureus  and MRSA. The yeast Candida albicans showed a varied response.


  • Anne Leahy-Gilmartin

    Technical Team Leader, Microbiology, School of Healthcare Science, Manchester Metropolitan University

  • Valerie Edwards-Jones

    Emeritus Professor of Medical Microbiology, Manchester Metropolitan University, UK