The aim of this study was to determine if shop-bought honey was free from contamination and suitable for use on equine wounds, and to investigate the effect of a number of different types of uncontaminated honey on the growth of equine pathogens.
Twenty-eight honeys were collected from sources ranging from supermarkets to bee keepers, and were cultured on sheep blood and MacConkey agar. Ten bacteria were collected from equine wounds, these included: methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Escherichia coli, Streptococcus equi, S. equi subsp. zooepidemicus, Enterococcus faecalis, Acinetobacter baumannii, methicillin-resistant Staphylococcus epidermis (MRSE), Staphylococcus sciuri, and Pseudomonas aeruginosa. Uncontaminated honey was incorporated into agar at a variety of concentrations and the plates were inoculated with the 10 bacterial isolates.
Of the 28 honeys tested, 18 were contaminated with bacteria and/or fungi including Bacillus sp. and Proteus sp. Of the uncontaminated honeys, 8/11 were effective against all 10 isolates at concentrations from 4 to 16%. Overall, Manuka 20+ and heather honey performed best.
These findings suggest that many honeys have antimicrobial properties, and may be effective in the treatment of wound infections. The concentrations at which honey samples inhibited microbial growth, were typically less than 16%, much lower than is likely to occur at the surface of an infected wound treated with honey.
The use of shop-bought honey on wounds should be avoided, as contamination with potentially pathogenic microbes appears to be common. Honey sourced within the UK is as, and in some cases more, effective than medical grade honey sourced in New Zealand. In many regions of the world access to expensive antimicrobial drugs are limited; therefore, honey may provide a local, inexpensive alternative.
Ethical animal research
Study approved by University of Glasgow Ethics and Welfare Committee. Sources of funding: Study funded by Glasgow Vet School and Kruuse UK Ltd. Competing interests: None.