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by Tracey Brown, director of Sense About Science

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Blog


 

March 2014

Should we be worried about 'dirty' stethoscopes?

This is a guest blog by Laura Macdonald, Healthcare Scientist at the Infection Control Team, Health Protection Scotland.

You may have seen news stories that stethoscopes have been found to be ‘dirtier’ than doctors’ hands, and contaminated with the ‘superbug’ MRSA. So, should we be worried and if so, what is the health profession doing about it?

The stories are based on a study published in the journal Mayo Clinical Proceedings. In the study, samples were collected from doctors’ hands and from their stethoscopes after physical examinations of patients. The researchers found that doctor’s fingertips were the area most contaminated with bacteria, followed by stethoscope diaphragms. The researchers also found the antibiotic-resistant bacterium MRSA on doctors’ hands and stethoscopes after 38 of 50 examinations on patients known to be colonised with the bacterium.

This study isn’t the first to investigate this issue. And from the existing body of evidence it is reasonable to conclude that stethoscopes do become contaminated with bacteria after use, and could be a vehicle for transmission of pathogens in hospitals. But we can conclude no more than that.

The healthcare environment is not sterile, and we would expect to find bacteria on objects in that environment. However, most would cause us little concern. Intact skin is an effective barrier to most microorganisms so stethoscopes are considered to be ‘non-critical’ or ‘low-risk’ medical devices, because they are usually in contact with intact skin. Guidance from the CDC states that ‘virtually no risk’ has been documented for transmission of pathogens to patients through contaminated stethoscopes.

Of course, absence of evidence is not evidence of absence, and we must recognise the possibility of a risk to patient safety, however low, and act accordingly. This particular study recommends the need to ‘systematically disinfect stethoscopes after each use’.

Reassuringly there is guidance for decontaminating communal equipment such as stethoscopes. For example Health Protection Scotland advocate decontamination between patients, while CDC guidance recommends that, at a minimum, stethoscopes are decontaminated when visibly soiled and on a ‘regular basis (such as after use on each patient or once daily or once weekly)’.

We know, however, that compliance is not 100%. So, is there an alternative for busy healthcare workers? One study carried out in the intensive care unit and emergency department of a US hospital, explored the use of stethoscope covers impregnated with silver ions, which are believed to have antimicrobial properties. The results were disappointing – antimicrobial covers were found to be significantly more contaminated than uncovered stethoscopes.

The original study looked at stethoscopes immediately after doctors had performed examinations. Had the researchers taken samples after doctors had the opportunity to adequately decontaminate their stethoscopes (and hands!) before moving on to the next patient, the news headlines may not have been quite so alarming.


Antimicrobial surfaces derived from tea, wine and chocolate? Promising - but a long way off

This is a guest blog by Dr Jon Otter, research fellow at the Centre for Clinical Infection and Diagnostics Research at King’s College London.

I have recently been looking at the potential for developing safe, effective antimicrobial surfaces. The focus of my interest has been hospitals and healthcare settings, but the potential applications of antimicrobial surfaces are much broader: consumer, food, laboratory and many more. So I was very interested to help Justine with the reply she received when she Asked for Evidence about antimicrobials surfaces derived from foods such as green tea, red wine and dark chocolate.

The discovery of this new type of antimicrobial coatings is a great story: researchers at Northwestern University, Illinois, detected a colourless residue left behind in kitchen sinks by certain foods. They then synthetically produced similar compounds in the laboratory and found that they had similar properties.

The paper describes the initial discovery and experiments to test the ability of two substances to kill Pseudomonas aeruginosa and Staphylococcus aureus. The paper contains a lack of experimental detail here: Where did they obtain the P. aeruginosa and S. aureus for these experiments? What concentration was applied? Was it a wet or dry inoculum? What was the contact time? The paper reports a ’30-fold’ reduction but this is moderate in disinfection terms and considerably less than most other candidates for antimicrobial surfaces.

The authors of the paper should be congratulated for performing such detailed work, but some of the claims in the accompanying news piece on the University’s website are bold. For example:

“The coatings innately have properties that are very beneficial to saving lives and keeping people healthy. Without any further modification, they can help prolong the life of a medical device, reduce inflammation in a patient and prevent bacterial infections”.

Whilst this may be true, it would depend on the coated medical device being shown to have safe and durable antimicrobial properties, and demonstrate clinical benefit through properly designed studies. The release also talks about ‘killing bacteria on contact’. The level of detail in the study makes it difficult to appraise the antimicrobial properties of the coatings. They clearly have some antimicrobial traits but this may be moderate compared with other antimicrobial surfaces.

Overall these polyphenol-based coatings are a promising candidate for producing antimicrobial surfaces. However, there is a long way to go before they are ready for widespread adoption for healthcare and other applications.


A precautionary tale

This is an article published on the Society of Biology blog on 28th March. You can read the full piece here.

Ahead of the Society of Biology’s upcoming Policy Lates event on the precautionary principle, Tracey Brown of Sense About Science gives her view on some of the issues surrounding the principle and its application.

What would you say if I suggested farmers start using a compound that could mess with your hormones in order to improve crop yields? I’ve conducted some pretty strict testing which indicates that it is safe but I can’t be sure; I haven’t got evidence that shows it is completely safe for you to be exposed to it over many years – I may never have evidence to put any hypothetical harm beyond doubt.

But that doesn’t matter, because the answer’s no anyway, right? We’re not going to take the chance. Now, how about if I told you that this compound would replace one that is persistent in waterways and which is being sprayed with increasing frequency because its effectiveness has dropped as the fungus it kills has evolved resistance? (All that extra spraying demonstrably harming ladybirds and other beneficial insects.) And, by the way, when I say mess with your hormones, I mean in doses that you’ll never be exposed to. In fact if you want to go into the detail a bit, what I really mean is that it has been shown to interact with the endocrine system, as many things you encounter on a daily basis do – including much of your food – and there’s no evidence that this particular interaction is harmful.

Continue reading this article here.


Ask for evidence on antimicrobial products and policies

Antibiotic resistance and ‘superbugs’ have in the last few years become a focus of research efforts and public health campaigns. The UK Chief Medical Officer called it a “ticking time bomb” and the World Health Organisation says it’s a major public health risk. When there’s a focus on an issue like this we often see products being promoted and policies put in place in response. Hospitals and GP surgeries are adopting new policies on hand-washing, on doctors’ white coats and ties, and screening patients for MRSA. Products from socks to banknotes, air conditioners to paint are marketed with claims that they will kill germs.

Are these claims evidence based or are we seeing public anxiety about superbugs used as a marketing tool? One way to find out is to Ask for Evidence. And lots of people have been asking and have let us know the responses they got.

Some of them have asked us whether the responses they get are good evidence. Which is where our Ask for Evidence partners come in. The Society for General Microbiology, the Society for Applied Microbiology and the journal Lancet: Infectious Diseases have volunteered their scientists to help tell us what kind of evidence they would expect to see for products and policies and to help people make sense of the evidence they get.

We’re putting these evidence hunting stories online over the next few days. So check back here tomorrow or follow #AskforEvidence on Twitter and Facebook to see what the evidence is behind antimicrobial stethoscopes, silver infused socks, bacteria killing curtains and more.  

 

 


Q and A on plastic packaging with the British Plastics Federation

I have been spending some time recently trying to persuade scientists who work in different industries to speak directly to the public. It’s part of our public led, expert fed approach. It means speaking directly to their consumers, in human language and not hiding behind euphemism. It means responding to questions that are sometimes rude and that can be wrapped up in all sorts of assumptions. It is important that industry scientists answer consumers’ questions about their area, not just independent scientists.  

So I’m really pleased that the British Plastics Federation has agreed to join a live Q&A on plastic packaging in a few weeks time. Scare stories about bisphenol A, PVC and phthalates are still circulating, they regularly come across journalists’ desks and we get calls about them. We’ll ask one of the independent toxicologists we work with to join too, though it is hard to find one that hasn’t at some point worked with industry because that is what they do.

Send your questions about plastic packaging to enquiries@senseaboutscience.org. We have had questions on this subject already and any new ones that don’t repeat the points already made we’ll add to the list for the Q&A.