Potassium in honey withdraws the moisture in bacteria thus destroying it.
This is an excerpt from Dr. Jarvis' book Folk Medicine
" It is no mere theory but has been proved that bacteria cannot live in the presence of honey for the reason that honey is an excellent source of potassium. The potassium withdraws from the bacteria the moisture which is essential to their very existence.
At the Colorado Agriculture College in Fort Collins, Dr.W. G. Sackett, a bacteriologist, determined to put honey, to the test. He frankly did not believe that honey would destroy disease bacteria. So in his laboratory he placed various disease germs in a pure honey medium and waited. The result astounded him. Within a few hours' time, or at most in a few days, each of the disease microorganisms died. The typhoid-fever-producing germs died within forty-eight hours. Other similar germs called A and B typhosus, perished after only twenty-four hours. A microorganism found in bowel movements and water which resembled a typhoid bacillus died in five hours. Germs which caused chronic broncho pneumonia were dead on the fourth day. It was the same with the particular bacteria associated with a number disease conditions such as peritonitis, pleuritis, and suppurative abscesses. Dysentery-producing germs were destroyed in ten hours. All these findings may be read in Bulletin No. 252, published by the experimental station where Dr. Sackett conducted his tests. Dr. Sackett was not alone in his experiments. These tests were duplicated and substantiated by Dr. A. P. Sturtevant, bacteriologist in Bureau of Entomology, Washington, D.C.; by A. G. Lockhead, working in the Division of Bacteriology in Ottawa Canada; and by numerous others."
http://www.jcrows.com/jarvis.html
http://jcrows.com/honeyantibiotic.html