Superbugs Are Becoming More and More Tolerant to Alcohol-Based Hand Sanitizers

A new study from Australia has revealed that superbugs found in hospitals may be growing resistant to common hand sanitizers.

A new Australian study has found that dangerous bacterial species is becoming tolerant to hospital grade disinfectants. Most hospitals around the world use hand rubs or washes containing isopropyl or ethyl alcohol to kill bacteria, but new research shows this might not be enough. 

Bacterial samples taken from Melbourne hospitals over a 19 year period shows that the drug-resistant species Enterococcus faecium is adapting to this approach. Dr. Sacha Pidot from the Doherty Institute was prompted to investigate possible resistance after noticing that infections linked to E. faecium are increasing. 

Study examined samples from a 19 year period

To test their theory they screened 139 E. faecium isolated bacterial samples or isolates collected between 1997 and 2015 and studied how well each survived when exposed to diluted isopropyl alcohol. The study showed that the older isolates were more tolerant to alcohol. 

To further test the theory, different isolates were seeded into mouse cages, analyses showed that the alcohol-tolerant isolates better colonized the guts of mice housed in the cages after the cages were cleaned with isopropyl alcohol wipes. Alcohol gel and wipes have been used extensively in medical environments since the mid-2000s when an international hand-washing program helped to massively reduce the rates of common ‘superbugs’. 

Hand-washing helped save thousands of lives

Bugs like MRSA were killing thousands of people on average each year. “All over the country MRSA rates were falling, that was great because patients were doing much better and the risk of serious infections was reduced,” said Professor Paul Johnson of the University of Melbourne, who helped lead the research. 

“But we also noticed a gradual increase in vancomycin-resistant enterococci (VRE) infections, this seemed like a paradox because both infections should be controlled by standard hand hygiene.” The research showed that analysis of the bacterial genome revealed several mutations in the genes of the tolerant isolates. 

Further study overseas needed to confirm research

The study concludes that further analysis of isolates in other parts of the world is necessary before any major conclusions can be drawn.

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“In many of the major hospitals around the world VRE is going up, like in Australia,” said Professor Tim Stinear, a microbiologist and another of the study’s authors. “So we’re very keen to see whether the same patterns of alcohol tolerance are in other hospitals worldwide.”

The study highlights the need for a global effort to study and mitigate the ways in which microbes can build resistance to not only drugs but to alcohol and other ingredients inside disinfectants. 

The paper was published in Science Translational Medicine.