Testing the efficacy of topical antimicrobial treatments using a two‐ and five‐species chronic wound biofilm model

• Published in: Journal of applied microbiology 2022-01, Vol.132 (1), p.715-724
• Main Authors: Nedelea, Andreea‐Gabriela, Plant, Rebecca L., Robins, Lori I., Maddocks, Sarah E.
• Format: Article
• Language: English
• Subjects: Anti-Infective Agents - pharmacology; Antiinfectives and antibacterials; Antimicrobial agents; Bacteria; Biofilms; Chronic infection; E coli; Humans; Iodine; Medical dressings; Polyhexanide; Pseudomonas aeruginosa; Species; Staphylococcus aureus; Streptococcus infections; Wound infection; Wound Infection - drug therapy
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/jam.15239

Aims The effectiveness of commercially available wound dressings and a HOCl gel formulation was tested against two‐ and five‐species biofilms in a dynamic in vitro chronic wound infection model. Method Two‐species biofilms (Pseudomonas aeruginosa and Staphylococcus aureus) were cultured using a biofilm flow device and treated with wound dressings containing silver, iodine, polyhexamethylene biguanide, crystal violet or HOCl gel at 5 h. Five‐species biofilms (P. aeruginosa, S. aureus, Enterococcus faecalis, Streptococcus pyogenes and Escherichia coli) were similarly cultured and treated with HOCl gel at 5 and 24 h. Multidose experiments used two‐ and five‐species biofilms with HOCl applied at 24, 48 and 72 h. Results None of the treatments completely disrupted the biofilms and, with the exception of silver, bacteria recovered in number post‐treatment. HOCl was most effective when applied to 24 h established biofilms with most activity against P. aeruginosa. Recovery post‐treatment was negligible with HOCl applied at 24 h and multiple doses indicated that bacteria were not becoming tolerant to treatment. Conclusions Realistic models are necessary to test the effectiveness of antimicrobial wound treatments to ensure findings are clinically translatable. HOCl gel shows promise as a new topical antimicrobial for wounds, especially due to its ability to inhibit P. aeruginosa. Significance and Impact of the Study This study highlights a need for robust in vitro data to support development and use of wound treatments that can only be obtained from the refinement of realistic infection models. Furthermore, it indicates the potential use of HOCl gel for chronic wound management.