New Zealand has a higher incidence of Staphylococcus aureus infections than anywhere else in the developed world, and there has been a significant increase in the number of infections over the past decade, with Māori and Pacific children particularly affected.
Over usage of an antibiotic is likely to have contributed to this paradoxical increase in serious skin infections, according to results from a Health Research Council funded study. This revealed an increase in the prevalence of resistance in Staphylococcus aureus from 17% in 1999, to 28% in 2013. Dr Deborah Williamson, the clinical microbiologist who lead the study, made the statement in a recent press release that “The increase that we’ve seen in the incidence of serious skin infections in New Zealand children has happened at the same time as an increase in the dispensing of topical fusidic acid to treat skin infections”(1).
Fusidic acid is an antibiotic derived from the fungus Fusidium coccineum and was first released for clinical use in the 1960’s. A 2% fusidic acid cream is currently recommended as a first-line treatment for serious skin infections such as impetigo (school sores), infection of the hair follicles and boils. Most of these are due to the bacteria Staphylococcus aureus, including the notorious methicillin resistant Staphylococcus aureus (MRSA). Like all antibiotics, drug resistance can develop, and this is invariably at a rate proportionate to the extent of usage.
In a paper published in the New Zealand Medical Journal last December, Dr Williamson reviewed the history and usage of topical antimicrobials in New Zealand (2).
This painted a somewhat alarming picture, and the fusidic acid story is an all too familiar one. Another topical antimicrobial agent widely used throughout the 1990s, mupirocin (Bactroban©), was for many years made available to purchase ‘over-the-counter’ (OTC). This led to high levels of use, and subsequent high rates of resistance, and by 2000, approximately 14% of S. aureus isolates displayed high-level resistance to mupirocin(3) . From April, 2000, regulatory changes lead to mupirocin being restricted again to ‘prescription only’, and the resulting decreased usage lead to a fall in the prevalence of high-level mupirocin resistance in S. aureus from 14.2% in 2000, to 8.3% in 2014 (4).
New Zealand is not alone in having a high rate of bacterial resistance to topical antimicrobials, and resistance to antibiotics poses a major global threat, according to a 2014 report by the World Health Organisation(5). Resistance is happening in every region of the world, and unless some major developments take place soon, humankind could be heading towards a time when once again, antibiotics cannot be relied upon to protect against simple infections including those that are risk factors associated with surgery. Development of strategies to mitigate further increases in antimicrobial resistance to topical treatments, is urgently required(6, 7).
Key to this, should be effective wound management. This should combine mechanical-chemical procedures such as debridement, antiseptics, and antimicrobial supportive compresses to help remove the biofilm (an association of microbes and slime which adheres to the surface of the wound, delaying granulation tissue formation and migration of epithelial cells).
Limitation of the level of usage of drug-based antimicrobials, or using two or more of them together rather than alone, and avoidance of topical antibiotic use in common conditions such as acne, are other ways to help reduce the likelihood of resistance(8).
Plants contain a large number of diverse chemicals (phytochemicals) which they produce as defence tools to enable them to survive in their particular environment, and some of these have potent antibacterial activities which can help us fight a wide range of common skin infections.
The New Zealand native Manuka (Leptospermum scoparium) is one of these, and the ability of certain forms of Manuka Honey to act as potent healing agents for wounds and ulcers, is becoming increasingly recognised(8). Many clinical trials have now shown manuka honey dressings to have unique healing properties in chronic leg ulcers and other stubborn skin infections, and synergistic antimicrobial activities with various antibiotics, have recently been reported(10,11).
Manuka’s medicinal properties extend way beyond those of the honey that bees manufacture from its pollen, however, and other parts and extracts of this wonderful plant, have therapeutic activities. Manuka essential oil has also been shown to exhibit powerful antimicrobial properties, particularly against Staphylococcus aureus and other Gram positive bacteria, yeasts such as Candida albicans and fungi such as Trichophyton rubrum, responsible for athletes foot. Manuka oils which are rich in beta triketone compounds, appear to have the strongest antimicrobial activity.
The extent to which topical application of an extract of this plant can rival drug-based treatments at overcoming sores, was highlighted by a research project by two students at Whangaroa College in Northland recently. After hearing about a fellow student’s spider bite that wouldn’t heal until it was treated with a native plant preparation, the two students, Cheyenne Rush and Georgia Mills, decided to investigate the antibacterial properties of manuka essential oil and an extract of another native plant kawakawa (Macropiper excelsum).
Their experiment, which they entitled Te Rongoa Māori , involved collecting and growing colonies of bacteria, spreading these onto agar plates and applying a quarter of a teaspoon of each product to be tested. The relative rates of decline of the bacteria was recorded daily for 14 days, for the manuka oil and kawakawa extract preparations, in addition to the well known antiseptics Savlon® and Betadine®, which were applied to other agar plates as controls.
The results showed that manuka oil was the most powerful antibacterial, followed by Savlon® then Betadine®, with the Kawakawa leaf extract the least effective. Cheyenne and Georgia’s project thus showed that a simple, traditional plant preparation can be more effective than prominent antiseptic products in fighting wound colonising bacteria. It also won them a top prize at the recent Top Energy Far North Science and Technology Fair, which involved more than 150 participants from 10 schools in upper Northland(12).
- Media Release from the Health Research Council, Soaring rate of skin infections linked to resistance.NZ Doctor, 20 September 2016.
- Williamson D et al, A bug in the ointment: topical antimicrobial usage and resistance in New Zealand. NZ Med J 2015; 128(1426):103-9.
- Upton A et al, Mupirocin and Staphylococcus aureus: a recent paradign of emerging antibiotic resistance. J Antimicrob Chemother. 2003; 51:613-617.
- Heffernan H et al, Demographics, antimicrobial susceptibility and molecular epidemiology of Staphyloccosu aureus in New Zealand, 2014. https://surv.esr.cri.nz/PDF_surveillance/Antimicrobial/Staph/2014Saureussurveyreport.pdf
- Antimicrobial Resistance: Global report on surveillance. World Health Organisation, who.int.ISBN 978 92 4 156474 8; (http://www.bbc.com/news/health-27204988).
- Williamson D et al, Missing in action: an antimicrobial resistance strategy for New Zealand. NZ Med J, 2015; 128(1427):65-67.
- Williamson DA, Hefferman H. The changing landscape of antimicrobial resistance in New Zealand. NZ Med J 2014; 127(1403):41-54.
- Walsh TR, The Lancet Infectious Diseases, 2016; 16(3): 23-33
- Carter DA, Front Microbiol 2016; 7:569
- Muller P et al, PLoS One 2013; 8(2):e57679
- Liu M et al, Front Microbiol 2015; 5:779.