Evaluation of short exposure times of antimicrobial wound solutions against microbial biofilms: from in vitro to in vivo

K. Johani, M. Malone, S. O. Jensen, H. G. Dickson, I. B. Gosbell, H. Hu, Q. Yang, G. Schultz, K. Vickery

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)
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Objectives: Test the performance of topical antimicrobial wound solutions against microbial biofilms using in vitro, ex vivo and in vivo model systems at clinically relevant exposure times.

Methods: Topical antimicrobial wound solutions were tested under three different conditions: (in vitro) 4% w/v Melaleuca oil, polyhexamethylene biguanide, chlorhexidine, povidone iodine and hypochlorous acid were tested at short duration exposure times for 15 min against 3 day mature biofilms of Staphylococcus aureus and Pseudomonas aeruginosa; (ex vivo) hypochlorous acid was tested in a porcine skin explant model with 12 cycles of 10 min exposure, over 24 h, against 3 day mature P. aeruginosa biofilms; and (in vivo) 4% w/v Melaleuca oil was applied for 15 min exposure, daily, for 7 days, in 10 patients with chronic non-healing diabetic foot ulcers complicated by biofilm.

Results: In vitro assessment demonstrated variable efficacy in reducing biofilms ranging from 0.5 log10 reductions to full eradication. Repeated instillation of hypochlorous acid in a porcine model achieved <1 log10 reduction (0.77 log10, P = 0.1). Application of 4% w/v Melaleuca oil in vivo resulted in no change to the total microbial load of diabetic foot ulcers complicated by biofilm (median log10 microbial load pre-treatment = 4.9 log10 versus 4.8 log10, P = 0.43).

Conclusions: Short durations of exposure to topical antimicrobial wound solutions commonly utilized by clinicians are ineffective against microbial biofilms, particularly when used in vivo. Wound solutions should not be used as a sole therapy and clinicians should consider multifaceted strategies that include sharp debridement as the gold standard.
Original languageEnglish
Pages (from-to)494-502
Number of pages9
JournalJournal of Antimicrobial Chemotherapy
Issue number2
Publication statusPublished - 1 Feb 2018

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Copyright the Author(s) 2017. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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