Why are they using ethanol in the hospital

Prevention of infection : Alcohol-tolerant germs

Certain antibiotic-resistant bacteria can also withstand alcohol-based disinfectants without dying off. This is what researchers report in the journal "Science Translational Medicine". They had gut germs of the type Enterococcus faecium examined from Australian clinics.

Hand disinfection with alcohol-containing gels and liquids is an important means of preventing the spread of microorganisms in clinics. Martin Exner, President of the German Society for Hospital Hygiene, is concerned about the study. He says such alcohol-tolerant bacteria could also occur in this country. “So far we have only seen antibiotic resistance as a problem. Now we also have to deal intensively with alcohol tolerances. "

The bacterium changed from 2010 onwards

In clinics around the world, it is common for employees to disinfect their hands and work surfaces with alcoholic agents. Visitors are also encouraged to use donors with the funds. Ethanol and isopropanol are used. They should kill germs within a very short time. The most important mechanism of action is that the membranes of the bacteria are severely damaged.

The scientists working with Sacha Pidot from the University of Melbourne concentrated on the intestinal bacteria E. faecium. In clinics, variants of it that are resistant to several antibiotics cause problems. Especially in patients with a weakened immune system, they can lead to urinary tract and wound infections and even life-threatening sepsis. The number of infections with E. faecium is increasing worldwide. Pidot and his team tested the extent to which isopropanol killed the germs on a total of 139 samples that had been taken in two clinics in Melbourne between 1997 and 2015.

In a first experiment, the scientists examined how the various samples reacted to a solution containing 23 percent by volume isopropanol. It turned out that bacteria isolated in clinics after 2010 got along much better with the alcohol than bacteria isolated earlier.

A cage full of germs

Common disinfectants based on isopropanol are dosed significantly higher at 70 percent by volume. So the researchers did another experiment with mice. They contaminated cages with various strains of E. faecium and then wiped them off with cloths containing 70 percent isopropanol. They then placed mice that had previously been treated with antibiotics in the cages for an hour and checked a week later which strains had settled in the intestines of the animals. They found that mainly a tribe of E. faecium, who had previously been identified as alcohol tolerant, colonized the mice. In addition, they found genetic changes in genetic tests that could be responsible for alcohol tolerance, but without being able to clearly demonstrate this in later tests.

Guido Werner, who heads the hospital germ department at the Robert Koch Institute, says he does not assume that a problem similar to that of resistance to antibiotics is imminent: “Otherwise we should have already seen that the usual strategy for outbreaks would be resistant germs, namely intensifying the disinfection, would be unsuccessful ”. They are also isolates of E. faecium from only two clinics in Australia. A mechanism comparable to clearly identifiable antibiotic resistance genes has not yet been proven despite an intensive search. He also doubts that the cage experiment, for example, is suitable for depicting the situation in hospitals: the cages were literally “flooded” with germs before disinfection. "Hopefully no such high germ count can be found in any German clinic."

Also tolerance to chlorine agents

The phenomenon is basically not new either. In a Danish study, for example, strains of E. faecium proven. And it is well known that alcohol tolerance and antibiotic resistance often occur together. There are also such tolerances against other, chlorine-based agents. Dutch researchers, for example, pointed to strains of E. faecium decreased sensitivity to chlorhexidine. In contrast to their Australian colleagues, they were also able to prove a certain genetic change that affects a regulatory system of bacteria as the cause.

Whether alcohol tolerant E. faecium have already arrived in Europe must now be examined more closely, says Exner. It cannot be ruled out that other such strains will develop and establish themselves evolutionarily because they have an advantage in hospitals. Both Exner and Werner say that an intensive scientific examination of the topic is necessary. (with material from dpa)

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