PhotoHospital “superbugs” have become increasingly resistant to alcohol-based hand sanitizers and disinfectants in recent decades, a new study suggests.

After collecting bacteria from two hospitals in Australia between 1997 and 2015, researchers discovered that a “new wave of superbugs” -- one that is more resistant to the alcohol used in hand sanitizers -- appeared to emerge.

The bacteria’s improved ability to survive hand sanitizer lined up with the hospitals’ gradual increase in use of alcohol-based sanitizers.

Withstanding alcohol

For the study, the researchers focused on a bacterium called Enterococcus faecium. This bacteria is already resistant to some antibiotics and is a leading cause of dangerous infections acquired in hospitals, including sepsis and urinary tract infections.

During the study time period, strains of E. faecium developed an improved ability to withstand alcohol-based hand sanitizer. A DNA analysis of the bacterial samples showed that the samples with more tolerance to hand sanitizers had several mutations in genes involved in metabolism.

“We have proposed here that the significant positive relationship between time and increasing alcohol tolerance is a response of the bacteria to increased exposure to alcohols in disinfectant preparations and that the more tolerant strains are able to displace their less alcohol-tolerant predecessors,” the team said.

The researchers -- led by infectious disease expert Paul Johnson and microbiologist Timothy Stinear of the University of Melbourne -- said hospitals shouldn’t stop using hand sanitizer based on these findings.

"Alcohol-[based] hand-hygiene programs have been highly successful, particularly at controlling MRSA [methicillin-resistant Staphylococcus aureus], but also other types of hospital infections, and I would strongly advocate that we continue using hand sanitizer,” Johnson said.

However, the researchers said hospitals may need to use other disinfectants (such as chlorine-based ones) to keep pathogens such as drug-resistant E faecium at bay.

The study has been published in the journal Science Translational Medicine.


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