We are losing the war against bacteria. Not only are our strongest antibiotics becoming less and less effective. Now drug-resistant bacteria are finding a way to survive alcohol-based disinfectants.
And that has dire implications for hospitals already struggling against superbug infestations.
The Australian-based study, published in the journal Science Translational Medicine, was initiated in response to a disturbing trend: the rate of infection of some drug-resistant bacteria was actually on the rise in hospitals.
This didn't make sense.
In 2002, it became standard practice in Australian hospitals for alcohol-based hand sanitisers to be made available to doctors, nurses, staff — and even visitors.
Alcohol is pretty harsh stuff to bacteria. It quickly blasts through their cell membranes, causing them to burst. It's generally been thought bacteria would not find it easy to adapt to such a full-frontal attack.
The study found some superbugs were being knocked back by the alcohol assault: such as Staphylococcus aureus (MRSA).
But others continued to increase their rate of infections — such as Enterococcus faecium.
So the team, led by Paul Johnson and microbiologist Timothy Stinear of the University of Melbourne, compared samples of E. faecium collected between 1997 and 2015.
When subjected to a disinfectant bath of 23 per cent isopropyl alcohol, they noticed a distinct tipping point.
From 2010 onwards, E. faecium became much more likely to survive the alcohol. Its tolerance, in fact, was some 10 times higher than the older bacteria.
This test was followed up in a test on mice using commercial-grade hand sanitisers (which contain 70 per cent alcohol). Once again, post-2010 E. faecium thrived.
So, in the war against superbugs, medicine is experiencing another setback.
The ability of these bacteria to evolve quickly is now undermining "the effectiveness of alcohol-based disinfectant standard precautions".
"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 study reads. "(It) may, in part, explain the increase in [vancomycin-resistant Enterococci] infection that is now widely reported in hospitals in Europe, Asia, the Americas, and Australia."
The extent of such resistance among the world's diverse bacteria types is not yet known. But the implications could be enormous if as many bacteria are developing alcohol tolerance as there are becoming immune to antibiotics.
But the superbugs can't claim victory yet.
"Alcohol-based disinfectants remain an important general primary defence against cross-transmission of most microbial and some viral pathogens in health care settings," the study reads.
And, as with the use of antibiotics, the researchers say those who use hand sanitisers must use them correctly. They must ensure the sanitiser is not diluted, and they must rub their hands thoroughly until fully dry.