Extended Antibacterial Activity of Multi-Action Wound Treatment

Introduction: The aim of the study was to assess the antibacterial activity of a novel multi-action treatment (MAT*) over 24-hour and seven-day periods, reflecting the possible length of wear time in clinical use.

Method: Control and test dressings were prepared according to an adapted AATCC Test Method 100 method. A pre-determined volume of simulated wound fluid was added in daily aliquots over six days to pre-condition the dressings and mimic clinical use. One millilitre of Staphylococcus aureus or Pseudomonas aeruginosa bacterial suspensions was added to the preconditioned dressing and incubated for 24 hours at 37 ±2°C. Remaining viable organisms were quantified. Dressings were tested in triplicate. Additional tests were conducted whereby a suspension of Streptococcus pyogenes or Candida albicans and a volume of simulated wound fluid were added to the dressings contemporaneously and the samples were incubated for 24 hours before quantifying remaining viable organisms.

Results: Following 6 days preconditioning and 24 hours contact time, no viable S. aureus and P. aeruginosa were recovered from MAT or positive control dressings. This equated to an average Log reduction of 5.72 ±0.00 and 6.03 ±0.00 Log10CFUsample-1 compared to negative control at 0 hours. An average of 5.72 ±0.14 and 6.03 ±0.10 Log10CFUsample-1 viable S. aureus and P. aeruginosa were immediately recovered from negative control dressings.

In the test method with 24 hour incubation without additional preconditioning no viable organisms were recovered from MAT (limit of detection 10CFUmL-1). This equated to minimum log reductions of 4.57 and 4.03 Log10CFUsample-1 in S. pyogenes and C. albicans compared to the negative control dressing.

Discussion: The AATCC Test Method 100 is an FDA-recommended test to determine the antibacterial and antimicrobial performance of wound dressings. The additional stage of pre-conditioning the dressing with fluid mimics wound exudate more closely, creating a challenge that represents the dressing wear situation. MAT resulted in greater than 4-Log reduction in all organisms tested, demonstrating broad spectrum efficacy against key wound pathogens and results of this simulated use test support clinical utilisation. Future work will continue to assess effectiveness against a wider range of relevant pathogens.