Comparison of In Vitro Bacterial Susceptibility to Common and Novel Equine Wound Care Dressings.
Authors: Simpson Merrill, Hendrickson Dean A, Hyatt Doreene R, Rao Sangeeta
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Antimicrobial Efficacy of Equine Wound Dressings Rising antimicrobial resistance demands that equine practitioners have robust evidence for topical wound treatments, yet comparative data on newer options remain limited. Researchers at Colorado State University evaluated the minimum inhibitory and bactericidal concentrations of ten antimicrobial agents—including medical-grade Manuka honey, local honey, food-grade honey, hypertonic saline, silver sulfadiazine, and polyhexamethylene biguanide (PHMB) gauze and foam—against four clinically relevant pathogens: *Pseudomonas aeruginosa*, *Escherichia coli*, methicillin-resistant *Staphylococcus aureus*, and a field-isolated *Streptococcus equi* subspecies *zooepidemicus*. Contrary to marketing claims, Manuka honey showed comparable inhibitory activity to basic alternatives such as sterile gauze, sugar, and saline, whilst locally-sourced honey demonstrated superior bactericidal properties across most bacterial species. PHMB-impregnated dressings consistently achieved inhibition at higher dilutions than other agents, suggesting greater potency, and notably, all antimicrobials performed better against the field-isolated *Streptococcus* strain than laboratory-adapted cultures. These findings suggest that practitioners should reconsider expensive Manuka honey products in favour of more cost-effective options, whilst recognising that in vitro results may not fully translate to in vivo wound healing—further clinical studies are essential before revising current dressing protocols.
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Practical Takeaways
- •For equine wound management, PHMB-based dressings (gauze and foam) outperformed honey products and should be prioritized when treating wounds with common pathogens like Pseudomonas and Staphylococcus aureus.
- •If using honey-based treatments, locally-sourced honey may provide better antimicrobial results than premium Manuka honey at potentially lower cost.
- •In vitro results suggest further in vivo studies are needed before changing current wound management protocols, as laboratory findings may not translate to clinical efficacy.
Key Findings
- •Local honey demonstrated superior bactericidal activity compared to Manuka honey and commercial food-grade honey across bacterial species tested.
- •PHMB gauze and foam showed consistently higher antimicrobial efficacy at lower dilutions compared to honey, hypertonic saline, and silver sulfadiazine.
- •Streptococcus zooepidemicus isolate from equine wound samples showed greater susceptibility to most antimicrobials compared to ATCC lab-acclimated strains of P. aeruginosa, E. coli, and MRSA.
- •Medical-grade Manuka honey MIC/MBC values were comparable to sterile gauze, sugar, and hypertonic saline, suggesting limited advantage over simple treatments.