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Disinfection: “Plasma Makes Bacteria Cell Walls Burst“
Prof. Sigrid Karrer;
© University Hospital Regensburg
Never wash without using soap – this is a slogan that surgeons should keep in mind at work. Hygiene of the future may look quite differently though, according to recent physicist’s findings.
Sigrid Karrer works at the University Hospital Regensburg and treats patient’s chronic injuries by using so-called Cold Plasma, a form of electroconductive gas, which can kill off bacteria. MEDICA.de talked with the professor about cleaning hands without the use of water and soap, a very special cocktail and swimming pools.
MEDICA.de: Ms Karrer, washing hands without using water and soap- how is that possible?
Sigrid Karrer: By using a device that is about as big as a toaster and is called a Plasma dispenser. To disinfect hands, you briefly hold them under a plasma-gas air breeze, which is created by the device. Within a few seconds, all germs will be killed off. This way, hands are disinfected not just quicker and in a much gentler way for the skin compared to liquid disinfecting agents, but also much more efficiently. The plasma is able to reach even the smallest cracks, which are barely ever reached during ordinary washing.
MEDICA.de: Physicians have disinfected their medical instruments and devices by using plasma for many years. Why is it just now being used on human beings?
Karrer: Plasma is actually very hot, because it is a gas that becomes conductive through electric currents, similar to air during a thunder-storm. Heat is well suited to disinfect medical instruments, but on human skin it would cause severe burns. Now scientists have figured out a way to also produce Cold Plasma under atmospheric pressure. This gas has a lot less loaded particles and therefore a much lower temperature. As a result, it can also now be used on organic tissue like the human skin.
MEDICA.de: Currently there are studies about the use of Cold Plasma on patients. The University Hospital Regensburg, which is where you work, is participating as well. What exactly are you researching?
Karrer: Together with colleagues from the Schwabing Dermatology Center in Munich, we have treated a total of over 160 patients with chronic wounds. The Plasma machines are developed by the Max-Planck-Institute for Extraterrestrial Physics in Garching. Normally, infected wounds are treated by applying disinfectants directly on the wound or by using antibiotics. However, in doing so we are not always able to get the inflammation under control. We are also battling with resistance to antibiotics.
Many bacteria are resistant against antibiotics; © SXC
Now we are treating patients with Cold Plasma. The only thing they feel during this is a breeze of air on their skin, which is about two degrees above room temperature. The patients are treated daily for two minutes with the Plasma for the duration of their inpatient stay. Sometimes that’s only for one week, sometimes that’s for three or four weeks.
MEDICA.de: And how is the result?
Karrer: An interim analysis on 36 patients showed a highly significant bacteria count reduction of 34 percent on wounds treated with Plasma, compared to those control study wounds treated without Plasma but with the conventional disinfection methods. Whether the wound is actually also healing faster, is not clear yet. We still need to study this further.
MEDICA.de: Can you use Plasma only on chronic wounds or can it also be used for other illnesses?
Karrer: Cold Plasma is also effective for skin diseases like athlete’s foot. Research has shown that the germ-killing effect even works through socks. A Plasma dispenser would therefore be a very elegant possibility in the future for public swimming pools: Just hold your foot briefly under the Plasma stream and the fungus is treated or the skin is disinfected to prevent athlete’s foot. We are also currently researching whether neurodermatitis or other skin diseases with itchiness can be treated with Plasma. Plasma treatments in dentistry are also conceivable, for bacterial gingivitis for example.
MEDICA.de: That sounds fascinating. There is one catch with this though: We know that the treatment works, but exactly how the Plasma acts is still not known. Are there any speculations?
Karrer: Plasma is a cocktail made up of different molecules, which wreak havoc on bacteria. We are talking about free radicals, ozone, nitrogen oxides, hydrogen peroxide and ultraviolet rays- each in very small doses. The fact is, that Plasma makes bacteria cell walls burst and thereby kills them. Researchers have observed this in an atomic force microscope.
MEDICA.de: Plasma is deadly for germs, but it is not supposed to attack human cells. Why?
Bacteria can be destroyed much easier than human cells; © PHIL
Karrer: Bacteria is much more delicate. DNA in bacteria is not additionally protected by a cell membrane as it is in the case of human cells and can therefore be destroyed much easier. However, those effects are dependent on the Plasma dosage.
MEDICA.de: What adverse effects can Plasma treatments have?
Karrer: So far we have no hints of adverse effects. Tests have shown that treatment is not causing any damages, not even in genetic material. However, research is still in the early stages and there are no long-term studies yet.
MEDICA.de: How do you assess the future of Plasma in medical science?
Karrer: It is our vision to develop also small Plasma devices for doctor’s offices and for domestic use. This could be a Plasma toothbrush for example, which is briefly held before the teeth and within seconds teeth and gums are germ free because of the plasma rays. Even smaller instruments are conceivable like a pencil, with which you can treat pimples quickly and easily at home or with which you can disinfect wounds swiftly and free of pain. Until then, we still need to conduct research for a few more years.
The interview was conducted by Simone Heimann and translated by Elena O’Meara.