Medical-grade honey kills antibiotic-resistant bacteria - including Staphylococcus - in the test tube, and eradicates colonies on the skin of healthy volunteers, Dutch researchers report.
Meanwhile, Irish researchers say the use of honey dressings for wounds is associated with a statistically significant decrease in surface pH and a reduction in wound size.
The new studies are providing a deeper look into the science of how honey can promote healing. But while results are promising, much more work remains to be done before honey becomes a standard part of the pharmacopeia, researchers say.
The literature shows large variation in the antimicrobial properties of honey produced in different geographic locations, and even in differing batches from the same location.
The Dutch company Bfactory has tried to standardize the natural product with its Revamil, a medical-grade honey produced by bees in the controlled environment of a greenhouse.
"The killing rate at 24 hours varied by concentration and pathogen, but 40 percent by volume honey proved to be completely lethal to antibiotic-susceptible and -resistant isolates of the pathogens," Dr. Zaat says.
The bacteria examined were Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae and Klebsiella oxytoca.
Researchers next measured the efficacy of Revamil in controlling skin colonization over 48 hours in 42 healthy volunteers.
"The median level of skin colonization was reduced 100-fold at the honeyed sites compared with the control sites on patients," Dr. Zaat says.
Median colonization at the treated patches of skin declined from 26.5 to 1 colony-forming unit (cfu), while the control areas showed an increase from 21.5 to 110 cfu over the same time period.
It was impossible to culture any bacteria from 81 percent of the honey-treated sites and 21 percent of the control sites.
The research was conducted at the university under a grant from the Dutch government to Bfactory. It was published in the June 1 issue of Clinical Infectious Diseases.
Elsewhere, researchers at the Royal College of Surgeons in Dublin, Ireland, focused on wound healing. Investigators used Medihoney (Derma Sciences), a brand of Manuka honey from New Zealand that is cleared for medical use in the United States and Canada.
The study recruited 17 patients with 20 nonhealing ulcers of various etiologies that had shown no improvement over the previous three weeks of treatment. Manuka honey dressings were applied to the wounds for two weeks.
The endpoints were change in surface pH and size of the wound.
"The use of honey dressings was associated with a statistically significant decrease in wound pH and a reduction in wound size," says lead author Georgina T. Gethin, Ph.D.
Wounds with a pH of 8.0 did not decrease in size, while wounds with pH 7.6 had a 30 percent reduction in size.
An elevated pH at baseline was associated with minimal healing, and each reduction of 0.1 pH was associated with an 8.1 percent reduction in wound size.
The study is scheduled for publication in the International Wound Journal.