What is Plasma Sterilization? How to Use Plasma Sterilizer.

Data gotten from the Center for Disease Control and Prevention (CDC) reveals that there are more than 1.7 million cases of infections thatare gotten from hospitals every year. That is almost 4.5 infections for every 100 patients that come to hospitals. What is even more ominous is the fact that there are nearly 100,000 fatalities from these cases. Needless deaths that need not have occurred if people and medical personnel took the process of sterilization as a top priority.

It is outrageous that, although we have been able to expand the frontiers of medicine, we still have people dying from things like infections. What then have we learnt from the works of Louis Pasteur and Robert Koch about eliminating dangers of infections?

The germ theory of disease states that infectious diseases are caused by pathogens and getting rid of these microorganisms greatly reduces the chances of someone getting infected.The realization of the deadly effects of microbes and the increasing importance of infection control is placing greater focus on sterilization techniques. While disinfecting reduces these harmful pathogens from surfaces it is sterilization that kills all the microorganisms- beneficial or not.

We have all seen commercials for disinfectants and you would always hear it kills 99.9% of germs 100% of the time. Well it is true. Only what they conveniently forget to mention is that the 0.1% that is still alive is the pathogens- disease carrying microbes so it is important to remember that disinfectants do not eliminate all microorganisms and are used only on inanimate or non living objects.

Furthermore the amount & kind of organisms killed or inhibited not only depend on the kind of microbes but also on the kind of disinfectants used as the best disinfectants won’t work well unless the temperature is just right, concentration of disinfectant is wrong or there is a lot of dirt on the surface. There are basically two kinds of disinfectants in the market. Bacteriocidal and Bacteriostatic. Bateriocidal kills the 99.9% microbes while Bacteriostatic inhibits the growth of the microbes.

Sterilization can be achieved using heat, chemical, filtration, irradiation and high pressure processes. The only problem with a few of these methods is that surfaces, instruments and medical devices that had to be sterilized were made from materials that could be destroyed by heat, moisture or chemicals.

The demand for an innovative method of sterilization that would not use heat, moisture or chemicals and yet be effective spurred researches and in the 1950s Ethylene Oxide gas was discovered for sterilizing these sensitive devices but the ETO is a carcinogen which seriously limited its use. The past decade has witnessed tremendous progress in the research and development of effective low temperature sterilization methods. We now have Peracetic Acid Immersion (which was released in 1988), Ozone Sterilization (which was cleared by FDA in 2003) and the Plasma Sterilization which has proven to be an appropriate alternative

sterilization procedure. This sterilization technology based on plasma was patented in 1987 and produced commercially for the American markets in 1993.

Plasma Sterilization uses very low temperature Hydrogen Peroxide gas plasma technology to sterilize surfaces, instruments and devices. The germicidal effects of plasma have been known for decades but it is only recently that we have begun to apply this technology to industry. Medical Personnel were intrigued with The Plasma Sterilizer as it cut out the ideal sterilization time cycle to 45 minutes (the time cycle with the ETO was 16 hours), had improved load humidity management, didn’t need aeration, had better heat distribution, shallow penetration of gas plasma, was safer for use (as there was supposed lack of emission) and money would be saved for the institution.

The gas plasma is generated by removing electrons from a gas to produce charged nuclei and free electrons. It works by ensuring that the plasma heat output (around 45oC) intensifies the action of the chemical and that there are no toxic residual remains on the sterilized materials.

Nowadays Gas Plasma Sterilization is widely utilized for the sterilization of spores as spores are more tolerant than other microbes. It also has the ability to inactivate endotoxins and lipid A.

There are some really good Gas Plasma Sterilizers being sold commercially today but public opinion show that the widely recognized sterilizer manufacturer is Sterrad. Other notable manufacturers include MoonMed and Tynsol.

The main ingredient used for sterilization is Hydrogen Peroxide (H2O2 which is highly concentrated (approximately 59%). Cellulosic materials, such as medical grade papers and autoclave pouches, neutralize the sterilizing agent by rapidly interacting with the oxidizing agent and its radicals resulting in an aborted cycle. What this means invariably is that we should watch the kind of materials that come in contact with the sterilizing agent during the process so there won’t be inadequate Sterilant concentration.

Gas plasma sterilizer has a shallow penetration depth of approximately 10–20nm so it is easy to achieve a sterility assurance level of 10-6 which means the gas plasma sterilization only kills one layer of bioburden.

Plasma will have important applications in medical and industrial settings in the future which mean Plasma Sterilization methods will require further research and investigation. The future success of this technology may depend on close collaboration between microbiologists and physical chemists.