Infection Control Today - 12/2003: Chemical Sterilants

Chemical Sterilants Revolutionize Decontamination

By Kathy Dix

Sterile processing departments (SPDs) have an array of choices for the methodof sterilization, but deciding which approaches to use often comes down to thechicken or the egg argument although they all have the same purpose,each systems users will always have its proponents and detractors.

Gas and heat were the primary methods of sterilization for many years.Charles Hughes, general manager at SPS Medical, a sterilizer-testing laboratory,says, By 1957, when I was born, an EO (ethylene oxide) gas sterilizer becameavailable by the Castle Sterilizer Company. When I left school teaching yearsago, I went to work for Castle Sterilizer. I spent a lot of evenings in theirlibrary learning, and found it fascinating that EO gas sterilized the fuelpropellant at NASA that lowered the first lunar module down on the moonssurface. They sterilized it because they did not want to contaminate the lunarsurface with anything that was manmade or from the Earth.

In 1988, STERIS SYSTEM 1 was approved; in 1993, ASPs STERRAD (whichuses hydrogen peroxide) was approved. The hydrogen peroxide system, likeperacetic acid, lessened reprocessing time. The hydrogen peroxide system cyclelasted through a 45- or 50-minute cycle, while the peracetic acid systemrequires 30 minutes. Hughes compares this processing time to the two- or four-hour EO cycle, whichis followed by eight to 12 hours of aeration.

When you think of whats been used, EO gas has been the number oneproduct still, Hughes says. He clarifies, however, that the shorter-durationchemical reprocessors have made significant inroads into hospitals.

Prices differ significantly depending on the method, Hughes points out. TheSTERIS system began retailing for $16,000, while the STERRAD system entered themarket costing $110,000, and the newly approved TSO3 ozone sterilizer isexpected to carry a similar price tag. This device creates its own sterilantusing medical-grade oxygen, water and electricity, leaving oxygen and vaporizedwater as its emissions.

Now, youd think everybody would stick with STERIS SYSTEM 1, but thedisadvantage is that its a liquid sterilizer, and all the devices have to beimmersible. Thats not the case with EO gas, STERRAD or with the ozone sterilizer, says Hughes. They really are the only options for a hospital industryuses radiation, which is considered a low temperature process as well. Therestwo types of radiation, but a radiation facility is not something thatsconsidered practical for a hospital, nor is it technically an FDA-approvedprocess.

Hughes references a 1999-2000 study that reports that the sterilizer marketis a $100 million industry, with an additional $20 million in sterilantconsumables.

In an aside, Hughes disputes the rumor that EO is being phased out. Atleast 50 percent of hospitals still do have gas. People who actually work with it will tell you they hate that vicious rumor,because it will continue to be around for quite some time, he affirms.

The Truth About Liquid Chemical Sterilants

There is no perfect liquid chemical germicide. Some are better thanothers; it depends on the use, says Martin S. Favero, PhD, director of scientific and clinical affairs at AdvancedSterilization Products. Favero notes that for endoscopes specifically, Theresbeen a huge shift away from glutaraldehyde to orthophthalaldehyde (OPA) for thesimple reason that people dont like to fiddle with OSHA, and they want to getaway from the irritation that the staff is experiencing when they handleglutaraldehyde.

Glutaraldehyde was introduced in 1963; that particular sterilant hasexcellent materials compatibility attributes, and thus lower repair costs thanwith many of the oxidative formulations. However, use of glutaraldehyde isaccompanied by respiratory irritation and an unpleasant odor. These effects ledto the adoption of OPA, which has a shorter cycle than glutaraldehyde.

With the formulations that are oxidative in nature (including peraceticacid and hydrogen peroxide), their advantages are that they are very goodmicrobicides, and they also do not have any environmental issues, Faveropoints out. But the No. 1 disadvantage is that they have materialscompatibility problems. Certain types of materials are reacted with, and theresboth cosmetic and structural damage to instruments after repeated reusings.

The difference between gas sterilization and chemical is that some gassterilization can be considered a terminal sterilization procedure, whileall liquid chemical sterilization is considered non-terminal sterilization.The gas method sterilizes wrapped instruments; the chemical method, however,leaves the items unwrapped. Thus, the sterilized instrument needs to be usedimmediately; if it is stored instead, it is still unwrapped and therefore immediatelycontaminated, Favero adds.

The Benefits of Chemical Sterilants

In 1996, according to the Food and Drug Administration (FDA) web site, liquidchemical sterilants used for processing critical and semicritical medicaldevices were exempted from the definition of a pesticide under the FederalInsecticide, Fungicide and Rodenticide Act and are no longer regulated by theEnvironmental Protection Agency (EPA). FDA now has sole regulatoryjurisdiction over liquid chemical sterilants and/or high level disinfectantsused to process reusable critical and semicritical medical devices, says thesite.

The chemical sterilant is a biocidal agent; its effective againstviruses, its tuberculocidal, bactericidal, fungicidal and the granddaddyof all sporicidal. If you can prove that you can effectively kill spores,all the other organisms that are questionable have been killed long before youcan kill spores. Those are the most difficult organisms to kill, says TerriAntonucci, senior director of clinical and customer education at STERISCorporation.

Explains Stephen Loes, vice president of global marketing at STERIS, Whenyoure looking at instruments costing $15,000 to $30,000, you dontnecessarily want to have a large inventory of them. And when youre doing nineor 10 procedures a day, you want to be able to reprocess your scopes quickly andget higher usage of them. The greatest savings come from hospitals and surgerycenters being able to reduce their inventory of very expensive equipment.Instead of one usage a day, theyre getting up to 10.

Liquid chemical systems are designed to be safe for costly temperature-sensitive devices, which include flexible and rigid endoscopes, cameras andlight cords. You can sterilize anything thats immersible, anything thatcould withstand the temperature, which is between 50 and 56 degrees centigrade, notes Antonucci.

These systems may not all reside in the sterile processing department (SPD);instead, they may be located near the site of patient care. There certainlyare several hundred SYSTEM 1 Sterile Processing Systems installed in SPDs, butthey are especially useful at or near the site of patient care, so its anapplication that would be more in the operating room, or in the endoscopy lab,or in the ambulatory surgery department, or in the bronchoscopy lab, saysAntonucci.

When asked who actually processes the devices, Loes says that staff nursesand technicians do it themselves. Its designed for nurses and technicianswho work right in the surgical department to process the devices, Antonucciexplains. They clean them, they prepare them according to the manufacturersrecommendations, then when theyre trained on how to use the process theyre the ones who process the devices.

And when asked how the nurses feel about performing a non-traditional nursingtask by reprocessing instruments, Loes says, They all felt it was a veryvaluable device for the OR and made them more effective. Theyre moreconcerned about infection in the patient.

It gives them a method of controlling their devices, Antonucci agrees. If they need it for the next case, they have it right attheir fingertips. It hasnt left the department and theyre not having tomake calls to see where it is. They have complete control over it.