Drug-resistant superbugs, already a big problem in hospitals, may have learned a new trick, researchers reported Wednesday.
They may have evolved resistance to alcohol — the ingredient in hand sanitizers and disinfectants that are one mainstay of hospital infection control, Australian researchers said.
If true, it could be even harder than it already is to control the spread of infection in hospitals, the researchers wrote in the journal Science Translational Medicine.
If bacteria can evade the effects of alcohol, it will come as a surprise to many microbiologists, who have assumed that it could not happen. While bacteria can evolve the ability to resist antibiotics, for instance by pumping them out, alcohol kills more efficiently.
The team at the Peter Doherty Institute for Infection and Immunity in Melbourne identified and studied a strain of vancomycin-resistant enterococci called Enterococcus faecium. It is a common hospital nuisance and while not particularly deadly, it can make hospitalized patients even sicker. (Vancomycin is an antibiotic used to treat bacterial infections.)
"The development of alcohol-tolerant strains of E. faecium has the potential to undermine the effectiveness of alcohol-based disinfectant standard precautions and may, in part, explain the increase in VRE infection that is now widely reported in hospitals in Europe, Asia, the Americas, and Australia," they wrote in their report.
Superbugs: Victims and outbreaks
Superbugs: Victims and outbreaks
Kelly and Ryan Breaux stand holding a portrait of their deceased daughter Emma Breaux, at their home in Breaux Bridge, Louisiana, on June 16, 2016. The husband and wife lost twins, Emma and Talon, to different superbugs that they contracted while in the neonatal unit at Lafayette General Hospital. U.S. Picture taken June 16, 2016. TO MATCH SPECIAL REPORT USA-UNCOUNTED/SURVEILLANCE REUTERS/Edmund Fountain
Kelly and Ryan Breaux sit holding a portrait of their deceased daughter Emma Breaux in their home in Breaux Bridge, Louisiana, on June 16, 2016. The husband and wife lost twins, Emma and Talon, to different superbugs that they contracted while in the neonatal unit at Lafayette General Hospital. U.S. Picture taken June 16, 2016. TO MATCH SPECIAL REPORT USA-UNCOUNTED/SURVEILLANCE REUTERS/Edmund Fountain
Four-year-old Luke Reimer, of Batavia, Illinois, holds a photograph, June 18, 2009, of his twin sister Madeline who died after being born with MRSA (Methicillin resistant Staphylococcus aureus), a bacterium that is resistant to many antibiotics. (Photo by Chuck Berman/Chicago Tribune/MCT via Getty Images)
Stephanie Hall (L), sits on the couch with her sister, Crystal Silva (R), and their ten year old niece Destini and nephew Kane in El Paso, Texas, U.S. on July 2, 2016. The children's mother, Natalie Silva, contracted Methicillin-resistant Staphylococcus aureus, more commonly known as MRSA, a skin infection that can turn fatal once it enters the bloodstream, when she went to the hospital to deliver Kane. After a 10 month battle with MRSA, Silva died, leaving Hall and the family to raise the two children. TO MATCH SPECIAL REPORT USA-UNCOUNTED/SURVEILLANCE REUTERS/Dan Dalstra
Monica Berckes, poses with the funeral program of her late mother Marianne Rumsey, who died at 61, several months after contracting MRSA during heart surgery, at her home in Secaucus, New Jersey, June 2, 2016. Picture taken June 2, 2016. TO MATCH SPECIAL REPORT USA-UNCOUNTED/SURVEILLANCE REUTERS/Mike Segar
Zachary Rubin (C), medical director of clinical epidemiology and infection prevention, and Robert Cherry (R), chief medical and quality officer for UCLA Health System, attend a news conference by UCLA Health System and county officials at the Ronald Reagan UCLA Medical Center in Los Angeles, California February 19, 2015. The large Los Angeles teaching hospital has told scores of patients they were possibly exposed to a drug-resistant bacterial "superbug" during endoscopy procedures that infected seven patients and may have contributed to two deaths. REUTERS/Jonathan Alcorn (UNITED STATES - Tags: HEALTH DISASTER)
A sample bottle containing E. coli bacteria is seen at the Health Protection Agency in north London March 9, 2011. For decades scientists have managed to develop new medicines to stay at least one step ahead of the ever-mutating enemy, bacteria. Now, though, we may be running out of road. Methicillin-resistant Staphylococcus aureus, commonly known as MRSA, alone is estimated to kill around 19,000 people every year in the United States -- far more than HIV and AIDS -- and a similar number in Europe, and other drug-resistant superbugs are spreading. Picture taken March 9, 2011. To match Special Report ANTIBIOTICS/ REUTERS/Suzanne Plunkett (BRITAIN - Tags: HEALTH SCI TECH)
An employee displays MRSA (Methicillin-resistant Staphylococcus aureus) bacteria strain inside a petri dish containing agar jelly for bacterial culture in a microbiological laboratory in Berlin March 1, 2008. MRSA is a drug-resistant "superbug", which can cause deadly infections. REUTERS/Fabrizio Bensch (GERMANY)
A view of the UCLA Medical Center in Los Angeles, California March 19, 2015. UCLA, the hospital at the center of the "superbug" outbreak that killed two people and infected seven last month has received poor patient safety scores and had its payments cut by Medicare for high rates of hospital-acquired infections. REUTERS/Lucy Nicholson
This digitally-colorized scanning electron micrograph depicts four magenta-colored, spherical methicillin-resistant Staphylococcus aureus (MRSA) bacteria in the process of being phagocytized by a blue-colored human white blood cells in this undated handout photo. TO MATCH SPECIAL REPORT USA-UNCOUNTED/SURVEILLANCE National Institute of Allergy and Infectious Diseases (NIAID)/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLYONLY
MIAMI - OCTOBER 17: Miami VA Medical Center hospital registered nurse, Rafael Sepulveda, pulls on rubber gloves while attending to patients in the Emergency room October 17, 2007 in Miami, Florida. The hospital has strict policies in place to ensure that the staff uses procedures in the fight against methicillin-resistant Staphylococcus aureus bacteria, commonly referred to as MRSA. The staph bacterium is resistant to most common antibiotics and has been responsible for more than nearly 19,000 deaths each year, according to the Centers for Disease Control and Prevention (Photo by Joe Raedle/Getty Images)
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The World Health Organization says antibiotic-resistant bacteria are a "fundamental threat" and has made fighting them a priority.
The Centers for Disease Control and Prevention estimates that 23,000 Americans die every year from drug-resistant infections.
The need to battle the spread of these germs is the reason why people are constantly reminded to wash their hands and why dispensers of alcohol foam or gel have appeared everywhere in hospitals and in other public spaces.
But the Australian team said their findings indicate that people will have to be careful how they use these hand sanitizers.
They started their study a few years ago, after Australia began a hand sanitizer campaign.
In a video released by the Doherty Institute, Dr. Paul Johnson, an infectious-diseases specialist, said the team wanted to know why a superbug known as MRSA, methicillin-resistant Staphylococcus aureus, was being so well controlled with the new national hand hygiene.
"But we started to notice also a gradual increase in VRE infections and this seemed like a paradox because both infections should be controlled using standard hand hygiene."
They ran a series of experiments, including one in which they took old samples of VRE dating back to 1997, and new samples from 2015, and grew them in dishes with diluted alcohol. The newer samples grew better.
"We were also able to identify and document the specific genetic changes that have occurred in the bacteria over the 20 years, which also helps to explain the increased tolerance," microbiologist Tim Stinear of the University of Melbourne, who helped lead the study team, said in a statement.
Not everyone is sold on the idea.
"The jury's still out as to whether this should raise a major alarm," said Dr. Cindy Liu, chief medical officer of the Antibiotic Resistance Action Center at George Washington University.
The report "doesn't seem like it could fully explain what is going on," added Liu, who was not involved in the research.
Nevertheless, she said, the study did seem to show that bacteria can survive in low concentrations of alcohol, which would provide a good reason for people to be more careful in using hand sanitizers. "The effectiveness of the alcohol depends on how you apply it," Liu told NBC News.
The Australian team said hospitals sometimes use hand sanitizers with two different germ-killing compounds, such as alcohol and chlorhexidine. That may be a better strategy going forward, they said. And they noted that foams and gels tend to be less effective at killing germs than liquids.
Liu agreed. Just as with washing hands with soap and water, it takes time to kill germs using hand sanitizers. People may not realize that they must thoroughly soak their hands. "You have to leave them on at least 30 seconds," she added.