The unusual antibacterial activity of medical-grade Leptospermum honey: antibacterial spectrum, resistance and transcriptome analysis

Abstract

There is an urgent need for new, effective agents in topical wound care, and selected honeys show potential in this regard. Using a medical-grade honey, eight species of problematic wound pathogens, including those with high levels of innate or acquired antibiotic resistance, were killed by 4.0-14.8% honey, which is a concentration that can be maintained in the wound environment. Resistance to honey could not be induced under conditions that rapidly induced resistance to antibiotics. Escherichia coli macroarrays were used to determine the response of bacterial cells to a sub-lethal dose of honey. The pattern of gene expression differed to that reported for other antimicrobial agents, indicating that honey acts in a unique and multifactorial way; 78 (2%) genes were upregulated and 46 (1%) genes were downregulated more than two-fold upon exposure to the medical-grade honey. Most of the upregulated genes clustered into distinct functional regulatory groups, with many involved in stress responses, and the majority of downregulated genes encoded for products involved in protein synthesis. Taken together, these data indicate that honey is an effective topical antimicrobial agent that could help reduce some of the current pressures that are promoting antibiotic resistance.

Honey-sensitive Pseudomonas aeruginosa mutants are impaired in catalase A

“…The antimicrobial power of Manuka honey has been widely documented (Blair et al, 2009;Roberts et al, 2015), whereas only recently, a remarkable number of reports about HD honey have been published (Majtan et al, 2011;Bobis et al, 2008;Kacaniova et al, 2011). Both types of honey were found effective against P. aeruginosa (Blair et al, 2009;Kacaniova et al, 2011).…”

“…Nevertheless, a likely minor role of other antistress activities cannot be ruled out, as suggested by transcriptomic studies performed on different bacteria exposed to catalase-treated Manuka honey (Blair et al 2009). …”

“…These studies mostly showed a change in the expression of genes involved in stress response both in Escherichia coli and in Staphylococcus aureus (Blair et al, 2009;Jenkins et al, 2014;Packer et al, 2012). Until now, no honey-sensitive bacterial mutants, to the best of our knowledge, have been selected and studied.…”

Analysis of Manuka (Leptospermum Scoparium) Honey and Development of Chitosan-Manuka Honey Film for Wound Dressing Applications

“…Manuka honey (Leptospermum scoparium) has been reported to exhibit inhibition against 80 species of bacteria and well characterized for its broad spectrum of antibacterial property [1][2][3][4] . Manuka Honey exerts non-peroxide antibacterial activity, which emphasizes the reason for Unique Manuka Factor (UMF), which is a phenol equivalent factor, to Leptospermum scoparium honeys 5 .…”

Honey, Food and Medicine: Scientific Rationale and Practical Efficiency in External Administration of Medicinal Honey for Wound Healing

“…Due to modern bacterial rising of antibiotic resistance, an essential argument for honey use in wound therapy is the remarkable anti-infectious activity, without development of bacterial resistance or emergence of mutants resistant to honey [3][4][5][6].…”