Fighting Off Wound Pathogens in Horses with Honeybee Lactic Acid Bacteria

Abstract

In the global perspective of antibiotic resistance, it is urgent to find potent topical antibiotics for the use in human and animal infection. Healing of equine wounds, particularly in the limbs, is difficult due to hydrostatic factors and exposure to environmental contaminants, which can lead to heavy bio-burden/biofilm formation and sometimes to infection. Therefore, antibiotics are often prescribed. Recent studies have shown that honeybee-specific lactic acid bacteria (LAB), involved in honey production, and inhibit human wound pathogens. The aim of this pilot study was to investigate the effects on the healing of hard-to-heal equine wounds after treatment with these LAB symbionts viable in a heather honey formulation. For this, we included ten horses with wound duration of >1 year, investigated the wound microbiota, and treated wounds with the novel honeybee LAB formulation. We identified the microbiota using MALDI-TOF mass spectrometry and DNA sequencing. In addition, the antimicrobial properties of the honeybee LAB formulation were tested against all wound isolates in vitro. Our results indicate a diverse wound microbiota including fifty-three bacterial species that showed 90 % colonization by at least one species of Staphylococcus. Treatment with the formulation promoted wound healing in all cases already after the first application and the wounds were either completely healed (n = 3) in less than 20 days or healing was in progress. Furthermore, the honeybee LAB formulation inhibited all pathogens when tested in vitro. Consequently, this new treatment option presents as a powerful candidate for the topical treatment of hard-to-heal wounds in horses.

Fig. 1

Pictures before treatment (top) and after (bottom) treatment of the wounds for the seven horses that completed the study with the honeybee LAB formulation. The horse owners took photos as outlined in protocol

Fig. 2

Examples of inhibition zones of the wound bacterial isolates from dual culture over lay assay, when incubated with the honeybee LAB formulation: Bacillus subtilis (a), Streptococcus equinus (b), Staphylococcus aureus (c), Bacillus pumilis (d), Staphylococcus equorum (e), and Enterococcus faecium (f)