Published: Tue, August 07, 2018
Medicine | By Brett Sutton

Increasing tolerance of hospital Enterococcus faecium to handwash alcohols

Increasing tolerance of hospital Enterococcus faecium to handwash alcohols

The World Health Organization says antibiotic resistant bacteria are a "fundamental threat", and the Centers for Disease Control and Prevention estimates the infections they cause claim 23,000 American lives each year.

VRE bugs, which can cause urinary tract, wound and bloodstream infections, can be hard to treat, mainly because they are resistant to several classes of antibiotics.

And Australia is not the only country struggling to clamp down on the spread of VRE in hospitals. It has to be noted that the usage of hand sanitizer in hospitals began to significantly increase in 2002.

The team screened 139 E. faecium isolates, isolated bacterial samples, previously collected between 1997 and 2015 from two hospitals in Melbourne, Australia, and studied how well each isolate survived when exposed to diluted isopropyl alcohol. 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.

This alarming development prompted Sacha Pidot and colleagues to investigate whether E. faecium could be developing resistance to the alcohols used in hand rubs. Once the cages were cleaned, the mice were placed in them for one hour.

"It shows that it is not just a laboratory phenomenon that we are measuring here; we are showing this characteristic [of the bacteria] transfers into being able to escape a standard infection control procedure", Timothy Stinear, one of the authors of the new paper, tells Nicola Davis of the Guardian. In fact, infections with drug-resistant E. faecium have been increasing in recent years, despite the growing use of hand sanitizers in hospitals, the researchers said. But as Stinear notes in a video posted by the Doherty Institute, scientists do not fully understand how and why Enterococcus faecium has evolved this adaptation.

In the second phase of the study, the resistant and non-resistant strains of the bacteria were spread on the floors of mouse cages, then a 70 percent alcohol solution was used to wash the surfaces.

Another limitation of the new study is its size: the scientists only focused on Australian hospitals. The acquisition by bacteria of resistance to alcohol suggests that in order to insure sterility, it is necessary to use combined detergents that kill bacteria not only through the content of alcohols.

"So we are using a lot and the environment is changing", he said.

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