Manuka Honey And MRSA

Question:
Is Manuka honey effective against MRSA (methicillin resistant Staphylococcus aureus)?

The short answer is:
Yes!  The laboratory studies seem to show how manuka honey has an antimicrobial effect against MRSA, and the clinical studies also suggest there could be a clinical advantage to using manuka honey to treat MRSA infection in certain circumstances.  However, clinical grade Manuka honey must be used.

One question about the health benefits of honey is whether or not manuka honey (also known as Leptospermum Honey) can be effective against MRSA.  Honey has been used for wound healing since ancient times (read my page about Manuka honey and wound healing), and it is known to have antimicrobial qualities (probably due to a number of factors: low pH; high sugar content; low water content; high peroxide levels). 

When looking at the effect of manuka honey on MRSA.  there are two factors to consider:

• what is the biological effect of manuka honey (what is the honey doing to bacteria); and

• what is the clinical effect of manuka honey (what is the effect on the levels of MRSA infection in patients, and on clinical outcomes such as wound healing).
  
  

Is Manuka Honey Effective Against MRSA? 
The Research Suggests It Is!

MRSA is ‘methicillin resistant Staphylococcus aureus’ – a bacterium that is resistant to a wide range of the most potent antibiotics, and is therefore very difficult to get rid of. 

It started as a hospital-acquired infection but is now sometimes a problem in other establishments, including prisons; care homes; farms and equestrian establishments. 

The initial symptoms are quite mild (small pimples or small boils), but this can progress quite rapidly to deep pus-filled boils, and the infection can become systemic, leading to severe symptoms such as toxic shock syndrome or necrotizing fasciitis ( a severe infection resulting in the death of body soft tissues).

So let's look at the research investigating the above points (please see the bottom of this article for links to the studies).

Biological effect of manuka honey on MRSA

Firstly here are a couple of the studies investigating what manuka honey does to the MRSA bacteria.

Jenkins et al, 2011 (1)
Jenkins et al studied the effects of manuka honey on MRSA cell division (bacteria need to divide in order to grow – if they cannot divide they die). 

The researchers used different strengths of manuka honey and compared it with artificial honey, and with an artificial honey that also contained what is called methylglyoxal (MGO). 

Why research the artificial honey, with or without MGO? 

Methylglyoxal (MGO) is a chemical compound, and it is naturally formed in the Manuka flower.  It can be manufactured industrially, but when bees forage on manuka flowers, then Methylglyoxal (MGO) occurs naturally in manuka honey, and is the dominant anti-bacterial constituent. 

One question that might be asked is whether there is something special about manuka, or whether the MGO is the principal compound effective against MRSA, and whether the manuka honey itself was necessary - or whether 'any old honey would do'.

In the results, MRSA cells treated with artificial honey alone, or artificial honey containing MGO, were not significantly different in size from untreated cells at any time point – suggesting that cell division had continued, whereas it was determined that MRSA cells treated with 5%, 10% or 20% from 30 min onwards had significantly larger cell diameters, suggesting cell division was prevented (cells grow physically larger before dividing).

The study states:

"Enlarged cells containing septa were observed in MRSA exposed to inhibitory concentrations of manuka honey, suggesting that cell division was interrupted. These changes were not caused by either the sugars or methylglyoxal in honey and indicate the presence of additional antibacterial components in manuka honey."

So, these effects were not caused by either the sugars or methylglyoxal (MGO) in honey and indicate the presence of additional antibacterial components in manuka honey specifically.

It seems that manuka honey has some special effect on the normal bacterial cell cycle, preventing cells from dividing, and ultimately leading to their death.

Specifically with regard to the artificial honey with MGO added, the scientists state:

Henriques et al, 2010 (2)
A study by Henriques et al also showed the same disruption to the normal bacterial cell cycle in MRSA.

Interestingly, manuka honey affects other bacteria too, such as E.coli (Escherichia coli):

Blair et al, 2009 (3)
Blair et al showed that manuka honey  also induces an unusual disruption of genetic processes in another bacteria, E.coli  and the researchers suggest that manuka honey could be useful in woundcare to help reduce some of the pressures caused by anti-biotic resistance. 

Summary:
So it seems that manuka honey has at least two effects on bacteria that may lead to bacterial death: prevention of cell division (MRSA); and a genetic effect that leads to problems for the bacteria in creating their own proteins (E.coli).

Clinical effect of manuka honey on MRSA

These ‘test tube’ studies are very interesting, but as stated earlier, they do not tell us what clinical effect manuka honey has on MRSA infections – it is necessary to carry out clinical studies in patients to ascertain this.   

Why?

There may be difficulties in the clinical setting not encountered in test-tube/petri-dish type situations – for example, if manuka honey is applied to a wound, does the manuka honey react differently?   Also, how should it best be applied, and in what quantity?   

Requirements for such research (which is both published and peer reviewed) is a fact of life and usually forms part of the decision-making process for infection control specialists, hospital pharmacists, surgeons, doctors, nurses  etc. 

So, what published clinical work is there to show the effect of manuka honey in patients?

Here are four clinical studies or case studies which though small scale, look very promising!

Natarajan et al (4)
Natarajan et al reported a single patient case study in which manuka honey eradicated an MRSA leg infection.

Visavadia et al (5)
Visavadia et al report successfully using manuka honey impregnated dressings on their maxillofacial unit.

Blaser et al (6)
Blaser et al reported full wound healing in seven patients with MRSA infected wounds – infections that had previously not responded to treatment with antibiotics.

Robson & Cooper (7)
Robson & Cooper report successful use of manuka honey in patients with damaged skin due to radiotherapy.  The authors reported complete healing of damaged skin areas.

Conclusion

The laboratory studies seem to show how manuka honey has an antimicrobial effect against MRSA, and the clinical studies also suggest there could be a clinical advantage to using manuka honey to treat MRSA infection in certain circumstances.

Note: Food-grade honey, and medical-grade manuka (or leptospermum) honey may be different!

Before anyone runs to the supermarket to buy manuka honey as an antimicrobial wound dressing, I should also quote the UK NHS website in relation to manuka honey:

Certified, medical-grade manuka honeys are available from specialist websites. 

Refs:

(1) The study can be found on this link: https://academic.oup.com/jac/article-lookup/doi/10.1093/jac/dkr340

(2) See the study: http://link.springer.com/article/10.1007%2Fs10096-009-0817-2

(3) See the study: https://www.scribd.com/document/284902781/The-unusual-antibacterial-activity-of-medical-grade-Leptospermum-honey-antibacterial-spectrum-resistance-and-transcriptome-analysis

(4) See the study: http://dx.doi.org/10.1080/095466301750163563

(5) See the study: http://dx.doi.org/10.1080/095466301750163563

(6) See the study: https://www.ncbi.nlm.nih.gov/pubmed/17927079

(7) See the study: https://www.ncbi.nlm.nih.gov/pubmed/19174588