Chlorine disinfectant bleach no more effective than water at killing superbug, says study

The chlorine disinfectant known as bleach, which is used in hospitals, is as ineffective as water at killing off a superbug, a UK study has said.

Bleach is applied for cleaning medics' scrubs and surfaces but it does not work against the spores of Clostridioides difficile (C. diff), a bacteria which infects millions of people globally each year, causing diarrhoea, colitis and other bowel complications, scientists have claimed.

C. diff is the most common cause of antibiotic-associated sickness in healthcare settings across the world.

Researchers at the University of Plymouth suggest that clinical environments may not be clean and safe for staff and patients and have called for disinfectants and guidelines that are "fit for purpose".

The scientists say that susceptible people who work and are being treated in these settings might unknowingly be put at risk of contracting the superbug.

More work should be done to find other ways to disinfect C. diff spores so the chain of transmission in clinical environments can be broken, the researchers say.

It comes as the threat to human health from superbugs is increasing amid a rise in antimicrobial resistance, known as AMR.

AMR occurs when microorganisms which cause diseases, including bacteria and viruses, are no longer tackled effectively by medicines like antibiotics and antivirals.

In the study, the scientists looked at how spores of three different strains of C. diff reacted to three clinical in-use concentrations of sodium hypochlorite (bleach).

The spores were then put on surgical scrubs and patient gowns, and analysed using microscopes to see if there were any changes.

C. diff spores could be recovered from surgical scrubs and patient gowns, with no observable changes, according to the results.

This highlights the potential of these fabrics as vectors of spore transmission, the researchers added.

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Dr Tina Joshi, associate professor in molecular microbiology at the University of Plymouth, said: "With incidence of anti-microbial resistance on the rise, the threat posed by superbugs to human health is increasing.

"But far from demonstrating that our clinical environments are clean and safe for staff and patients, this study highlights the ability of C. diff spores to tolerate disinfection at in-use and recommended active chlorine concentrations.

"It shows we need disinfectants, and guidelines, that are fit for purpose and work in line with bacterial evolution, and the research should have significant impact on current disinfection protocols in the medical field globally."