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Antibiotics and antimicrobial resistance - Expert Q&A
Antibiotics and antimicrobial resistance - Expert
Q&A
21 November 2016
Growing rates
of antimicrobial resistance could leave us without effective
drugs to treat serious infections - "the end of modern
medicine as we know it", according to the WHO's Margaret
Chan.
November 14-18 was World Antibiotic Awareness Week and Dr Siouxsie Wiles at Te Pūnaha Matatini planned an awareness campaign about antimicrobial resistance: InfectedNZ. It was postponed because of the Kaikoura earthquake and is running this week.
The Science Media Centre asked Dr Wiles and other experts to take part in a Q&A about antimicrobial resistance. This is an abridged version - you can access the full version and supporting materials on scimex.org.
Please feel free to use this Q&A in your reporting.
Dr Siouxsie Wiles, acting deputy director Te Pūnaha Matatini, University of Auckland:
What is antimicrobial resistance and what is causing it?
"Antimicrobial resistance is when microbes develop the ability to stop antimicrobials from affecting them. As most microbes replicate themselves and their genetic material fairly rapidly (some can divide in just a few minutes), and they can grow to large numbers (easily reaching population sizes in the billions if they have the right conditions), there are plenty of opportunities for resistant mutants to arise purely by chance. These mutants can then grow quite happily in the presence of the antimicrobial.
"A major factor in the development of resistance is the misuse and overuse of antimicrobials. So being used when they aren’t needed, or not being used correctly. Another worry is the use of similar antimicrobials in human medicine and in agriculture. For example, a fungus commonly found in soil has become resistant to the antifungal pesticides used in gardening and agriculture. Because similar antifungals are used in human medicine, these resistant fungi are now able to cause almost untreatable infections in some vulnerable hospital patients. And these patients can become infected just by being in a bed next to open window that looks out onto a garden!"
Is antimicrobial resistance something we should be worried about?
"Yes. Experts predict that within the next decade we will run out of antimicrobial medicines to treat many common infections. Part of the reason we are in this position is that most of the pharmaceutical industry pulled out of antimicrobial research decades ago, so the medicine cupboard is basically empty. Similarly, the vast majority of government and charity funding around the world has gone on researching non-communicable diseases. Any new antimicrobial compound discovered today could take a decade of development and testing before it would be available for doctors to use. The situation is a catastrophe on a par with global warming."
What does a future without antimicrobials look like?
"A future without antimicrobials will affect us all; rich and poor, young and old. In a world without antimicrobials, previously treatable infections will once again become deadly, or may require amputation to stop them in their tracks. Because antimicrobials are also used to prevent infection in vulnerable people, it will also become life-threateningly risky to do routine operations like caesarean sections and joint replacements, and treatments like chemotherapy for cancer."
What should we be doing to combat antimicrobial resistance?
"We should be adopting a multi-point plan to help combat antimicrobial resistance:
1. Husband our current antibiotics by only taking them when needed. And when they are needed, by taking them fully and completely to avoid creating resistant strains
2. Carefully keeping track of current levels of resistant organisms and where they are located, and providing this information to clinicians to help them prescribe antibiotics appropriately. Antibiotic stewardship programs in our hospitals that assist in the management of infectious diseases need support. We need a well-trained and microbiologically savvy workforce.
3. Restrict antibiotic use in our animals to the treatment of infection, not for weight gain or growth.
4. Support research aimed at developing new antibiotics. New classes of antibiotics are urgently needed and scientific research must be undertaken now to discover the best new ways to combat infection. This kind of basic research will underpin the development of the next generations of antibiotics, which will lead to new treatments for infected patients.
5. Lastly we need to rethink our relationship with bacteria. Most bacteria are not 'the enemy'. Most bacteria are not even pathogenic, and there are many more bacteria living in and on us, than our own cells! We need to learn more about what groups of bacteria promote health and what groups have potentially deleterious effects. Maintaining a healthy microbiome could turn out to be an vital new tool for global health."
How well does the general public
understand antibiotics and when to use them? Does this
affect their use?
"We have done
research with a range of ethnic groups, occupational groups
and the general population and found that misunderstandings
about antibiotics are very common. Overseas research has
also found this.
"Some common misconceptions that lead to
over-use of antibiotics are:
• Many people think that
antibiotics will cure illnesses like colds and flu. This is
not true because these are caused by viruses, and
antibiotics do not work on viruses (they only kill
bacteria).
• Many minor bacterial infections will get
better on their own and so taking antibiotics is unlikely to
make a difference for these.
• Some people
misunderstand what antibiotics are or what they do, so they
may take them to treat all kinds of conditions that they are
not helpful for."
How does antibiotic
understanding and use in New Zealand compare with other
countries you've worked in?
"New Zealand has
much better controls on availability of antibiotics than
anywhere else I know of. As far as I know, it’s impossible
to buy oral antibiotics in New Zealand without a
prescription. In most countries, it’s illegal, but it
happens. The quality of medicines is good in New Zealand,
and this is also helpful. In some countries substandard
medicines are common and this is likely to increase
resistance because people are inadvertently taking only
small doses.
"However, antibiotic use is high in New
Zealand compared with other OECD countries. It has climbed
dramatically between 2006 and 2014, and this is very
worrying.
"I think it is common for people to have
misconceptions about what antibiotics are and what they do
in all countries."
Q&A with ESR
How do we monitor
antimicrobial resistance?
"Most of the
information we have on antimicrobial resistance in New
Zealand comes from routine testing of bacteria undertaken in
microbiology diagnostic laboratories. The bacteria are
isolated from specimens taken from patients who have an
infection, for example, a urinary tract infection. The
patients may be in hospital or patients who present to their
GP with an infection.
"The results from this testing
(which is called ‘antimicrobial susceptibility testing’)
are used to calculate what proportion (usually percentage)
of bacteria are resistant to an antibiotic. For example,
from this testing we know that about 90% of
Staphylococcus aureus, a bacterium that causes
infections such as boils and abscesses, are resistant to
penicillin, the first antibiotic to be discovered. On the
other hand, this testing tells us that only about 8% of
Staphylococcus aureus are resistant to
flucloxacillin, the antibiotic now most commonly used to
treat infections with this bacterium.
"ESR collates the
antimicrobial susceptibility testing results from diagnostic
laboratories throughout New Zealand to estimate national
rates of resistance and also to monitor changes in rates.
In addition, ESR often collects the bacteria themselves from
the diagnostic laboratories and undertakes more extensive
antimicrobial susceptibility testing and specialist testing
to determine the genetic basis of
resistance."
Are there particular resistant
bacteria that are of most concern in New
Zealand?
"Rates of antimicrobial resistance are
relatively low in New Zealand compared with many other
countries, including some of our near neighbours in
Southeast Asia. However, resistance is generally increasing
in New Zealand. Of particular concern is the high rate of
resistance among Staphylococcus aureus to
fusidic acid that has emerged following years of high use of
topical preparations of this antibiotic. Also of concern
are so-called ESBL-producing bacteria, especially when they
cause infections in patients in the community who need to be
treated with oral antibiotics. Given the range of
antibiotics these bacteria are resistant to, there are very
few oral treatment options
available."
Science Media Centre NZ
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