This is cribbed from a post from a Dane on an e-mail group. The theme started as Manuka honey and then veered onto other honeys, including the almost ubiquitous Oilseed Rape, which seem to have the same properties. I found it interesting and hope you do.
A Dutch group of scientists accumulated the knowledge on the anti bacterial effects of honey, a summary was published in the German bee journal ADIZ. This is a translation from German into English by a Dane! I have tweaked the spelling and grammar a little.
The antibacterial effects are divided in 5 major points:
1) The osmotic effect. Due to the high sugar concentration, honey sucks water out of the bacteria and this kills them
2) Metabolism of sugars results also in Methylglyoxal, this is toxic. The human organism has certain enzymatic ways of getting rid of it, bacteria accumulate it and eventually die
3) Bees produce Defensines, chains of 33 – 47 amino acids, and these attact bacteria as well as vira. Asian bees (Apis cerana) produce more than melifera, i.e. Asian bees are more tolerent to the infections following after Varroa Destructor. Manuka and rape honey contain most of these defensines.
4) Hydrogen peroxide is formed by an enzyme in honey in the presence of water. This H2O2 is sterilizing.
5) Honey has a low pH value, 3.8 – 4.3, this inhibits bacterial growth.