October 14, 2011
Why honey works so well in the eyes against bacterial infection
Here's the secret:
Featuring an exclusive interview with distinguished Associate Professor Dee Carter
(Head of the Discipline of Microbiology, University of Sydney)
The latter bacterial pathogens, apart from infectious, can sometimes be extremely drug resistant. Among them the so-called ‘superbugs’ have developed resistance to almost every antibiotic ever developed by any pharmaceutical company.
Their very rapid development of resistance is what has led most pharmaceutical companies to stop employing their resources on the antimicrobial research.
A situation of medical emergency has established due to the fact that ‘superbugs’ can be particularly prevalent in hospitals, and are responsible for killing patients, particularly those in intensive care.
The essential need for an agent that effectively kills these organisms, especially in the treatment of wounds, has been the number one priority that has driven many scientists within the microbiology field to research every option available.
But, if there is no drug that can stop these plagues, what else there is?
An all time natural remedy: Manuka honey.
Manuka honey and jelly bush honey are produced by bees that feed off tea trees in New Zealand and Australia .
Here is when we seem to witness how the customs of indigenous tribes, who have known about the healing properties of the honey as well as many other natural remedies for as long as they remember, beat the attempts of the pharmaceutical companies to manufacture the nemesis of the superbugs.
Leading researcher in fungal genetics, Professor Dee Carter (University of Sydney's School of Molecular Bioscience) took part in the discovery of how honey would ‘sweetly but effectively’ kill infectious organisms. It is a privilege to interview Professor Carter on this subject, which has the potential to have a major impact on modern medicine.
Professor Carter, many thanks for participating in this interview, and of course please receive our congratulations for this important health discovery.
1. MDM_ The results from the research were published in the European Journal of Clinical Microbiology and Infectious Diseases almost a year ago now but when exactly was this discovery of the curative properties of the Manuka honey made, Professor?
1. PROFESSOR_ It’s been known for many hundreds of years that honey can be used to alleviate or cure a variety of ailments – well before is was known that these ailments are caused by micro-organisms. However, the pioneering work on Manuka honey has really been done in the past 20 or so years, largely driven by our colleague Professor Peter Molan in New Zealand, where the Manuka bush is native. During this time he and others, including our group, have tried to put some solid science behind the observation that honey has curing properties
2. The Manuka honey was already being sold in health food shops as a natural medicine but due to thereticence of the scientific community to consider some of these natural products nobody had tested the honey for its healing properties. What lead your research group to consider that there could be an effective anti-bacterial component in this honey at the time?
2. PROFESSOR_ I had an undergraduate student, Shona Blair, who had become very interested in the initial work coming out of the Molan lab on the effect of honey on bacterial pathogens. At the time nothing was known about what the “special factor” present in the honey might be that was having this effect – chemists like Professor Molan had been trying to isolate it but without success. As microbiologists we were interested in exploring the effects from the microbial point of view to see if this might be able to tell us more about the active components in the honey. We tested many different bacterial strains, including those resistant to 10 or more different antibiotics, and found that these were all equally susceptible to the killing effect of honey. Furthermore we have not been able to get bacteria to develop resistance to honey, when they will rapidly become resistant to other antibiotics.
3. MDM_ What was the general reaction of the leading researchers from other scientific groups on this discovery?
3. PROFESSOR_ Some scientists, particularly those with an interest in natural products, are very interested in and excited about the work. But it would be fair to say that there are some that see it as a bit off-beat and not really “serious science”. Which is curious as we use all of the same techniques that one would employ to test any uncharacterised antimicrobial substance. I think it’s just the perception that honey belongs on toast that gives rise to this attitude.
4. MDM_ Do you think this discovery could prompt other research groups to test the properties of common natural remedies that are being sold in health food shops?
4. PROFESSOR_ There is certainly a growing interest in exploring natural products for their health properties and in putting some solid science behind the ways in which these work. One of the issues with natural products, however, is that they often have low levels of active ingredients (which is why there are usually few issues with side effects) and these may vary since they are difficult to characterize. Also, different people may respond differently to them. So conducting a clinical trial and coming up with really robust data as is done for conventional drugs, where the active ingredient can be completely standardized, is often difficult. In addition, natural therapies often need to be employed over a period of time and don’t give the “quick fix” that we are used to, for example with antibiotics, leading to the perception that they don’t work. The science is therefore quite difficult, nonetheless it’s exciting to see more of it being done, and it holds a great interest to the general public.
5. MDM_ This honey is applied externally on bites and cuts as it acts on skin infections, hence being a good replacement to antibiotic and antiseptic creams. The bees that produce this honey feed of tea trees and apparently microbiological testing has confirmed the effectiveness of tea tree oil in fighting infection. However this type of oil only comes from the tea trees native to Australia.
Could the components of the Manuka honey and/or those of the tea tree oil in itself be genetically cloned?
5. PROFESSOR_ I should start by saying that tea tree oil is derived from a completely different tea tree species to Manuka and is not involved in the activity of Manuka or jelly bush honey. Since my expertise is in honey I can only really comment about this. We now know that at least part of the activity of Manuka honey is due to a small molecule called methylglyoxyl, or MG. You can purchase chemically synthesized MG from fine chemical companies. It will kill bugs but it’s also toxic to human cells in the pure form. There is something about it when in honey that allows it to selectively kill pathogens without harming the human cells – in fact honey as a whole product promotes wound healing. We have also tried spiking some MG into non-Manuka honey to see if we can simulate the antimicrobial and healing effects of Manuka, but this really doesn’t work. We believe there are other compounds present in honey, not yet characterized, that act with honey to produce the special antimicrobial and wound healing properties that it has. So no, I don’t believe we are yet able to make a simple derivative from a cloned (or otherwise synthesized product) – although this might be possible in the future.
6. MDM_ Due to your outstanding work for over the past 10 years you have been established as the leading researcher in cryptococcal genetics, with particular focus on molecular ecology and population genetics that underlie infection by Cryptococcus gattii. Would you be as kind as to explain to our readers what diseases these type of organisms are responsible for and where can they be found?
6. PROFESSOR_ Cryptococcus gattii is a very interesting pathogenic yeast. Yeasts are a type of fungus that occur as single round cells rather than long threads, and fungal pathogens often exist as a yeast form when infecting mammals. C. gattii is normally found in the environment and in Australia appears to have a close relationship with certain species of Eucalyptus trees, particularly Eucalyptus camaldulensis,also known as the river red gum. You can find C. gattii on other trees but is most reliably isolated from E. camaldulensis and close relatives. This makes it interesting to us here in Australia as the red gum is a native tree, but it’s also important worldwide as these trees have been extensively exported and are found in high numbers throughout the Americas, Africa and Asia. Under circumstances that are not well understood, C. gattii cells become aerosolized and can be inhaled by people and animals. We can usually clear the infection very efficiently, but in a small number of people the fungus will lodge in the lung and grow to cause pneumonia. And in a small proportion of these cases it can disseminate from the lung to other parts of the body, particularly the brain, to cause meningitis. Cryptococcal meningitis is a fatal disease without treatment, and treatment options are limited since fungal cells aren’t so different from human cells and antifungal agents can be toxic to us. We have been using molecular ecology techniques to try to understand how C. gattii spreads in the environment and contacts unlucky recipients. This interface between the ecology of an organism in the environment, and infection in a person or animal, are of great value in understanding infectious diseases, particularly as the environment changes through climate change, deforestation, agriculture and other ecological disruptions.
7. MDM_ You have been invited to speak in scientific conventions particular to your area of expertise in Australia, USA and have hosted visiting scientists from France, Britain, Vietnam and Iran, who have learnt molecular techniques and their application to fungi in your lab. What specific projects of investigation (and other) are you currently working on and which would you like to direct your efforts towards in the near future?
7. PROFESSOR_ I am very concerned about the lack of suitable treatments for so many microbial infections, such as the drug-resistant bacteria and the fungi. We are continuing our studies of honey and are particularly interested in how it is able to prevent resistance from developing – maybe this information can be used in the rational design of other drug treatments. For fungal pathogens my research has become focused on understanding the infectious process with the long-term aim of developing new therapies. In our study of Cryptococcus we are using a technique known as proteomics, which is able to characterise many expressed proteins at one time. This allows us to see what proteins a pathogen makes during infection, and also what proteins are made by a host to protect against infection. By characterising proteins that are produced by a fungus that is able to produce a serious infection – what we call a virulent strain – and comparing this to the proteins produced by a related fungus that can’t produce such a serious infection, we can get an idea of the proteins that are important in the infection process, which may be used to inform the drug development process.
MDM_ Thank you again Professor Carter for your participation in this interview, it is a privilege.
PROFESSOR_ My pleasure!
Paper: The Antibacterial Activity of Honey Derived from Australian Flora by Julie Irish, Shona Blair, and Dee A. Carter* [FULL ARTICLE LINKED]