Thursday, November 21, 2013

Antibacterial action of honey

Wounds to the lower limbs of horses can prove challenging to manage.  Recently there has been a growing interest in the use of honey in such cases.

Not all honey is the same. Its antibacterial quality depends on the type of honey and the conditions under which it was harvested and processed. Most honey contains hydrogen peroxide, which has antibacterial properties. Some types of honey contain other active components. For example, manuka honey is believed to have antibacterial properties due to high concentrations of methylglyoxal, a compound usually found in only low quantities in other types of honey.

Manuka honey, produced by bees foraging on manuka plants (Leptospermum scoparium), native to Australia and New Zealand, has been the subject of considerable research. Honey from other sources is often used in practice, but there has been little research into how effective it is.

Researchers at the University of Glasgow have been examining various different types of shop-bought honey to determine if they were free from bacterial contamination and suitable for use on equine wounds. They also investigated the effect of various examples of uncontaminated honey on the growth of equine pathogens, and  found that, in laboratory tests, certain varieties of honey are able to inhibit bacterial growth even at very low concentrations.

They found that many commercial sources of honey were contaminated with bacteria. The most commonly identified contaminating organism was Bacillus spp. However, potentially pathogenic organisms  (Proteus and Enterobacteraceae) were identifed in two honey samples.

Uncontaminated honey samples were subjected to further investigation to assess their antibacterial properties. Eight of the eleven samples tested were effective against all 10 bacterial isolates at concentrations from 4 to 16%. Overall, medical grade Manuka honey and a locally produced heather honey performed best.

The researchers conclude that many honeys have antimicrobial properties, and may be effective in the treatment of wound infections. They note that the concentrations at which honey samples inhibited microbial growth were much lower than is likely to occur at the surface of an infected wound treated with honey.

However, they advise that “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.”


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