TAMPA (AFP) - Some hospital superbugs are growing increasingly tolerant to alcohol-based disinfectants found in hand washes and sanitisers, allowing increasing infections to take hold, an Australian study warned on Wednesday (Aug 1).
Hand rubs and washes that contain disinfectants based on isopropyl or ethyl alcohol are widely used around the world, and have dramatically cut infections of one type of superbug, called methicillin-resistant Staphylococcus aureus (MRSA).
But researchers have noticed a rise in another kind of bacteria that lives in the gut, called Enterococcus faecium, and can be spread via catheters, ventilators or central lines in a healthcare setting.
"Drug-resistant E. faecium infections have increased despite the use of alcohol disinfectants, and currently represent a leading cause of infections acquired in hospitals," said the report in the journal Science Translational Medicine.
Enterococci account for about one in 10 cases of hospital-acquired bacterial infections around the world, and are the fourth leading cause of sepsis in North America and the fifth in Europe, according to background information in the article.
E. faecium, in particular, is believed to cause one-third of enterococcal infections in Australia, 90 per cent of which are resistant to the antibiotic ampicillin, and 50 per cent of which are also vancomycin-resistant.
"Costs associated with the management of patients infected with vancomycin-resistant enterococci (VRE) are high because of the need for isolation rooms, specialised cleaning regimens, and the impact on staff, bed availability, and other resources," said the report.
To better understand the reasons for this bacterium's spread, researchers analysed bacterial samples taken from two hospitals in Melbourne from 1997 to 2015.
"The isolates gathered after 2009 were on average more tolerant to the alcohol compared to bacteria taken from before 2004," said the report.
Being tolerant means the bacteria can survive exposure to alcohol longer.
The delay "is sufficient to allow the bacteria to escape alcohol killing and then cause infection", study author Tim Stinear, a microbiologist at the Doherty Institute for Immunity and Infection at the University of Melbourne, told AFP in an e-mail.
"The bacteria we examined in our study are a long way from becoming resistant to alcohol," he added.
More study is needed to confirm if these bacteria are also growing resistant to sanitisers in other hospitals worldwide.
Researchers are not sure why this particular type of bacteria is acting this way, but say it may be something about the physiology of E. faecium that makes it easier for the bacteria to evolve tolerance to alcohol exposure.
In the meantime, no one is suggesting hospitals stop using hand sanitisers, rather that other cleansing methods are needed, said Stinear.
"Our findings do not signal the end of hand sanitisers, but indicate you cannot rely solely on alcohol-based disinfectants to control E. faecium in the hospital/healthcare setting."