We’ve probably all seen headlines referring to MRSA (methicillin-resistant Staphylococcus aureus), E Coli (Escherichia coli) and Salmonella. Along with Pseudomonas aeroginosa these are all examples of superbugs, in that they have developed resistance to a number of antibiotics.
NB C difficile (Clostridium difficile), which has also appeared in media headlines, isn’t a superbug. In fact it lives harmlessly in many people’s intestines. However it can cause illness when certain antibiotics disturb the balance of normal bacteria in the gut.
Where are they most commonly found? The bad news is that they are most commonly found in hospitals. This is partly because patients in hospital tend to have weakened immune systems, due to age or illness and/or open wounds, so are more vulnerable to infection than their healthier counterparts. It is partly too because hospitals have a concentration of people living together, examined by doctors and nurses who have just touched other patients –hence the renewed focus on hand washing in hospitals.
Why do there seem to be more superbugs developing?
- Evolution – bacteria are a classic example of Darwin’s theory
- Antibiotics used in rearing animals for food (leading the World Health Organisation to conclude that antibiotics should be banned as growth promoters in animal feeds – a ban largely introduced in the European Union in 2006 but not yet in the USA)
- Excessive use of antibiotics – including over the counter sales without prescriptions in some countries
- Inappropriate use of antibiotics – including patients asking for antibiotics when they aren’t needed; or not finishing the course of antibiotics prescribed (where they have probably killed most of the bacteria but not those more resistant to antibiotics, helping them evolve their resistance)
- Poor hand hygiene by hospital staff - potentially spreading resistant organisms
- Population growth and global travel, helping superbugs spread more easily geographically
How big a problem are they? Superbugs have been found in hospitals across the developed world, from the USA to Australia, from Japan to Europe.
The World Health Organisation (WHO) warns that over 25,000 people a year die in the European Union (EU) as a result of infections caused by superbugs. In 2006 the Centers for Disease Control and prevention recorded some 19,000 deaths from MRSA alone in the USA.
Until recently research and development provided new drugs in time to treat bacteria that had become resistant to existing antibiotics but this is no longer the case – leading some to predict a global public health disaster.
One worrying further development has been the outbreak of community associated MRSA (CA MRSA) infections, for instance in the USA in prisons, sports teams, among military recruits, among illegal tattoo recipients, among Hurricane Katrina evacuees and among men who have sex with men – rather than just among patients with weakened immune systems in hospitals, which had been the norm previously.
What can we do to stop superbugs?
Handwashing by staff, patients and visitors when in hospital – to reduce the risk of contaminating surfaces and spreading infection. With superbugs like MRSA spreading via surface to surface, contact prevention is better then cure!
Develop new antibiotics, with archaeocins one potentially useful new class of antibiotics – although the number of new antibiotics isn’t keeping pace with the growth in antiobiotic resistance, so other strategies are likely to be needed, including:
Prescribe fewer antibiotics to slow the evolution of superbugs – hence, for instance, current posters in GP surgeries in the UK explaining that antibiotics have no effect on colds and flu – and then try to ensure that, when prescribed, patients take the full course of treatment to reduce the risk of more resistant strains surviving.
Maintain a strong immune system, for example by following the advice in our Diet section. The vast majority of those who die from superbugs are still those with weakened immune systems eg the Journal of the American Medical Association reported that 77% of US deaths from MRSA in 2005 occurred in people aged 65 or older, a group well known to have weakened immune systems..
Phage therapy – which uses bacteriophages (viruses that invade bacterial cells) and has been used and researched for decades in the countries of the former Soviet Union, in particular Georgia (whose Phage Therapy Centre is now owned by an American company).
Phage therapy has a number of advantages compared with antibiotics, including the ability of phages to evolve so that they can continue to destroy bacteria; and a more targeted response, meaning a smaller effective dose can be used, with less risk of adverse side effects.
However, it has its limitations. A phage will only kill bacteria if it is a match to the specific strain, so banks of different phages are needed; the phages need to be kept refrigerated until required; a physician needs special training to prescribe and use phages; and tailored phage treatments or mixtures need to be prepared – which makes it difficult to secure US regulatory approval, as there isn’t a standardized phage ‘product.’
One possible way forward is to develop phage based therapies, for instance by extracting lysine, the enzyme a phage uses to dissolve the bacterial cell wall and kill the bacterium. In principle the lysin should be able to kill entire families of bacteria (although some, such as E coli and salmonella, would remain immune).
Vaccines enhance the body’s natural defences (whereas antibiotics operate separately from the body’s normal defences) and an Australian organization (CSIRO) is one of those working on possible vaccines. However, unless superbugs become more prevalent there is limited financial incentive for pharmaceutical companies to make the major research and development investment required (as for new antibiotics too).
Develop viruses which kill bacteria – as with research at University College London, reported in New Scientist, where researchers identified and joined six viruses that ‘eat’ a common ear infection (P aeruginosa bacteria)
Wikipedia reports there is clinical evidence that topical dermatalogical preparations, such as those containing tea tree oil and thyme oil may be effective in preventing transmission of CA – MRSA.
Introduce copper fittings in hospitals. Trials at Selly Oak hospital in Birmingham, reported in 2008, found that replacing a set of taps, a toilet seat and a push plate on an entrance door with copper fittings killed up to 95% of bacteria on the surfaces whenever tested. Lead researcher Professor Elliott commented, ‘I have been a consultant microbiologist for several decades. This is the first time I have seen anything like copper in terms of the effect it will have in the environment.’
Manuka Honey is another potential lifeline. Researchers at the University of Wales have found that, in the laboratory, filtered medical-grade manuka honey can interfere with the growth of three types of bacteria commonly found in wounds, including MRSA – and even make MRSA more sensitive to antibiotics such as oxacillin. If clinical trials were to confirm this, this would suggest a potentially fruitful area for development.
Manuka honey contains high levels of a compound called dihyrdoxyacetone, present in the nectar of manuka flowers, which produces a compound believed to have antibacterial properties.
Published 01/05/2011, Review date May 2015