The hygiene mythbuster

17 June 2015

Clinical detergent wet wipes used in hospitals across the UK could be spreading superbugs, according to a new study led by Cardiff University. Cleaning Matters columnist Seán Derrig weighs in on matter

Unless you’ve been in a coma these last few weeks headlines like "wet wipes used to clean hospital wards spreading deadly superbugs" will not have escaped you. But just this once – despite in all cases the underlying copy merely regurgitating a press release – the headlines were pretty accurate.

The study in question evaluated detergent wipes in common use in the NHS. Scientists dried out carefully-controlled amounts of three types of bug onto metal discs then ran them through a marvellous piece of kit called a ‘Wiperator’. This ensured the wiping action was precisely the same no matter which wipe was being tested so performance could measured in a repeatable way.

The study posed two questions: first, how good was each wipe at removing bugs. Second, if the wipe was subsequently used on another surface, did the bugs stay on the wipe or did they escape?

These questions appear superficially simple but are very important. Detergent wipes are marketed as a convenient, ready to-use, disposable solution and so are being used in ever-increasing quantities for environmental cleaning. They are sold on the basis that they do two things: first to efficiently remove microorganisms from a surface, second to ensure those microorganisms remain stuck to the wipe, thus preventing any possibility of cross-contamination.

All wipes failed the first test – their performance at physically removing bugs was uniformly poor. All but one failed the second test; the bugs the wipes picked up got spread all over the place. The authors noted there were huge variations in different wipes’ performance which I won’t examine for reasons of space – but I think it a fair summary to say none covered itself in glory.

Here’s why this is so interesting: The Department of Health has a long-standing antipathy to disinfectants and its unswerving loyalty to detergents for general cleaning is a key driver in sales of these detergent wipes designed to remove bugs rather than kill them.


National guidance needs update 

The ability of microorganisms such as vancomycin-resistant enterococci, MRSA, Clostridium difficile and others to persist for prolonged periods on inanimate surfaces is well-known. Study after study shows common pathogens being isolated from ‘high-touch’ points in close proximity to patients. But as the evidence base supporting the significance of environmental transmission of pathogens grows, the advice that detergents or detergent wipes are best remains constant.

Which may be why the authors state "because detergent cleaning is advocated in many national guidance documents, it is imperative that such recommendations and guidance take into account the wipe limitations found in this study". It is incredibly rare to see such unequivocal language in a scientific paper. But will this new evidence change policy? I fear not.

The World Health Organisation published a report in 2011 showing hospital-acquired infection rates (sorry, we’re supposed to call them 'healthcare-associated' now) are far lower in Iran, Latvia, Mongolia and Ghana than in NHS hospitals. Yet the publication of this embarrassing and inconvenient fact changed nothing.

I make no criticism of the hard-working individuals at the sharp end of infection control who deserve the respect of us all – but one would hope that a well-constructed study, authored by a highly respected UK research group, published in a 'high-impact' journal such as the American Journal of Infection Control would be seized upon by decision makers. My challenge is I just can’t see that happening in an organisation led by a health secretary who believes interventions such as homeopathy – entirely based on magic rather than science – is a legitimate use of the public purse. Which is a bit like having a transport secretary that believes in broomsticks…

Seán Derrig is scientific director at Chemex International