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| Rethinking Steam Sterilization and
Hospital Cleanliness |
| Microorganisms or as some of us like to call them, “Bugs,” are one of the earth’s earliest life forms. Their simple architecture and DNA structure allows them to adapt to various environmental stresses and even elude human efforts to kill off the undesirable ones. In recent years, one need only glance at front covers of Newsweek and U.S. News & World Report to see what these
microorganisms are doing to our food supply (causing millions of cases of
food borne illness.) Other microbes pervade hospital walls and cause nosocomial infections, about 2 million cases annually in the United States alone.
With their ability to adapt to new environments and develop resistance to human weapons such as antibiotics, it is not surprising that microbes have become such formidable enemies. For many years one antimicrobial weapon against pathogenic microbes has been the steam sterilizer (autoclave). Its effectiveness was demonstrated decades ago and it is currently widely used in hospitals and research laboratories. A study recently conducted by Consolidated Stills and Sterilizers (Boston, MA) has demonstrated the release of bacteria from the exhaust/purge cycle of steam-jacketed autoclaves! The study was performed at the Tufts University School of Medicine and the results are presented in the British Journal of Biomedical Science (Marshall, et al., 1999).
A standard procedure in steam sterilization involves evacuating the air in the chamber so that the steam will have minimal resistance in penetrating the materials to be sterilized. Steam rapidly enters the sterilizer chamber and displaces the air within. This air is exposed to the microbes that may be present in the chamber (i.e. pathogen-contaminated garments and linens). At the start of the cycle the now contaminated air is expelled through the exhaust port and into the surrounding environment (e.g. hospital room). Coupled with this, it has long been known that sub-lethal heat can induce a stress response in which microbes temporarily become more heat resistant than they were previously. Furthermore, heat can cause DNA damage resulting in mutations. These mutations would usually go unnoticed but if there were a “selective pressure” the mutation could manifest itself. In a hospital environment one selective pressure could be antibiotics. The multiple resistance of Staphylococcus aureus from hospital environments is well-known and this organism is a common cause of nosocomial infections. What about other microbes?
In light of these findings Consolidated has developed a simple but effective solution to this problem. The accessory, known as the Consolidated
Bug Buster (patented), utilizes a high-efficiency filter to remove bacteria from the purged air. Any condensate formed is heated, vaporized, and discharged as a sterile vapor back into the sterilizer. Furthermore, the hot vapor sterilizes the filter thus killing any residual harmful bacteria.
The escape of microorganisms from steam sterilizers is a serious issue, especially for those individuals involved in the medicare industry, pharmaceutical industry, and research and development. It is prudent that steps be taken to prevent the release of any microorganisms from steam sterilizers. It’s time to rethink how we use such a common piece of laboratory equipment.
Marshall, B.M., H. Shin-Kim, D. Perlov, and S.B. Levy. Release of bacteria during the purge cycles of steam-jacketed sterilizers. British Journal of Biomedical Sciences 1999;56:247-252. |
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| Concerns For Hospitals, Research Laboratories, Universities, and Clean Room Applications |
Most people's gut feeling tells them not to stay in a hospital any longer than necessary. Hard-nosed managed care insurers agree, with an eye on the bottom line. Bill Barnstead, founder and president of Consolidated Stills & Sterilizers in Boston, Massachusetts, passionately agrees, but for a different reason: nosocomial infection. Not a household word yet by any means, but if Bill Barnstead has his way, it will be on the tongues and in the minds of dramatically more people, and "Soon" isn't soon enough.
Nosocomial (from the Greek "noso" for infection or disease and "comial" for hospital) infections are those contracted in the hospital environs. In recent years, the nature of nosocomial infections has become increasingly deadly with some hospitals dangerously contaminated by life-threatning strains of bacteria.
Four newborns were killed by bacteria in a Boston hospital recently. And while publicity about E-coli, a deadly and terrifying disease, brought drug resistant bacteria and infectious organisms into the kitchen and living room, public health concerns for some time have been focused critically on drug resistant infections such as tuberculosis. It is returning with significantly greater immunity to medications that have been, until now, effective in wiping them out. The Center for Disease Control (CDC) and the American Medical Association are concentrating their efforts on reducing overuse of the most powerful antibiotics such as Vancomycin, Streptomycin et al, to hopefully extend their effectiveness against a range of diseases while new drugs are being developed.
So what is Consolidated Stills' involvement in all of this? For starters, one needs to recognize Bill Barnstead as one who prefers to "Follow not where the path may lead, but go instead where there is no path and leave a trail." Many, if not most, of the innovations in stills, used to purify water for intravenous solutions, and sterilizers, used to kill bacteria and other organisms on medical and laboratory equipment, originated with his company.
Twenty-eight years ago, a question from a public health worker related to nosocomial infections triggered his thinking and he began to focus Consolidated's research on the role of hospital sterilizers.
As a result of its efforts over a 15 year period, Consolidated found cause to believe that sterilizers were inadvertently contributing to the problem of airborne germs in hospitals. For a very basic reason: Standard procedure in steam sterilization involves evacuating the air in the sterilization chamber so that the steam will have minimal resistance in penetrating the materials to be sterilized and that air, exposed to and contaminated by whatever germs are present, is being routinely expelled at the start of the process either into hospital atmosphere or externally to the unprotected environs. Hospital and laboratory personnel handling such materials are, of course, properly clothed and protected. But not the various environs into which these infectious organisms are being released and stay for long periods.
In addition to those "bugs" that escape the sterilization process via forced evacuation, other organisms with strong drug resistance may survive the full sterilization cycle. Barnstead explains that no bacteria is more dangerous than one with strong drug resistance which has been down for the count of nine and survived. Now it is in position to pass on it's greatly enhanced immunity to some of the most powerful drugs in our arsenal. The word arsenal is not lightly used, Barnstead says. "Hospitals have become the sites of such virulent bacteria because they have been virtual battlefields in the ongoing war between men and microbes."
Each time an infection is dosed with an antibiotic most of the microbes die; but a few, those with a mutant gene that allows them to resist the drug, survive and multiply. "Since a single bacterium can multiply exponentially within hours", he notes, "it doesn't take long for these battle-hardened bugs to get the upper hand. Such bacteria are precisely the ones we are most concerned about being released to unprotected environments." What is equally disturbing is the facility with which these organisms can almost immediately pass on their enhanced drug resistance to other bacteria, by contact and in solution, as observed by microbiology researchers.
Deadly Silence
Until now, very little has been written or discussed about this frightening medical problem. The average citizen is unaware of it; professionals in the scientific world do not want to talk about it. After all, if following manufacturer and government mandated procedures for effective sterilization and using the best equipment doesn't solve the problem, what do you do? You sure don't talk about it.
"Yes, you do", says Barnstead. With and estimated two million patients acquiring in-hospital infections each year, he wages a determined campaign to raise the awareness of people at every level...medical, scientific and lay. (He's even handing out little buttons with the word "NOSOCOMIAL" overprinted with the international symbol for "no")
Eliminating the Threat
On a positive note, Barnstead's tenacity has led Consolidated to pursue an aggressive program to demonstrate that this inadvertent release of harmful organisms is, in fact, being done world-wide on a routine basis. And, having done so, he has gotten other researchers interested in substantiating his findings in their own environments. Consolidated is ready and willing to show hospitals and medical and food research laboratories how to conduct their own tests that will verify that this ongoing contamination does exist.
Consolidated's more than ten years of focused research and development has resulted in devices and methods for eliminating or at least dramatically reducing the threat of in-hospital infection from incomplete sterilization. They represent the first breakthrough in steam sterilization in over fifty years.
The company has developed, and has patents in process*, covering several devices and techniques to insure that most infectious organisms do not leave the sterilizing chamber.
"It may take a bit longer to get to the 100% point," says Barnstead "but perfection is not easy to come by, if it is ever attained. Our research staff is still at work!" |
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| Are You Using
Clean Steam? |
Problem:
Steam sterilizers/autoclaves use steam as a sterilizing medium. With the aid of steam to complete heat transfer, we are able to significantly reduce both cycle length and temperature previously required in dry heat sterilization while also ensuring the necessary kill ratio for microbial targets. Steam is therefore a very desirable and effective method of sterilization.
The steam required in a sterilizer can be supplied in many ways. Steam can be manufactured specifically for an individual sterilizer in an integral electric steam generator, a gas fired generator, or an indirect steam heated generator. Steam can also be taken from a central steam source such as a separate steam generator or a building steam line.
When steam is supplied from a central source it is often what is termed "dirty steam". This refers to the quality of the steam and indicates that the steam contains chemicals, salts, and other undesirable elements/compounds used to clean large boiler systems. The carry over of these elements is the cause of various sterilization problems including, but not limited, to the following:
Shortened life span of the autoclave itself due to corrosive qualities of these elements exacerbated by naturally occurring high temperature and pressure conditions.
Shortened life span of expensive stainless steel and gold instruments and scissors exposed to these conditions.
- Staining of materials, color changes in cloths and fabrics.
- Carry over of rust, dirt, and other harmful solids into goods being sterilized.
- Incomplete sterilization due to the encapsulation of bacteria by rust, dirt and other particulates.
- Expensive additional maintenance and cleaning, not only for the chamber, but also in all solenoid valves, steam traps, door gaskets, etc.
Solution:
The good news is that this situation can easily and inexpensively be resolved:
1. The best solution is the application of an indirect heated steam generator. The theory behind the generator is simplicity itself. Use the available dirty steam in a heat transfer bayonet to heat a good water source. No carry over of undesirable elements, no costly filters to change, and a good water source can be ordinary tap water. Low purity D.I., R.O., and distilled water are also good choices, but avoid high quality (1 megaOhm or more) and softened water.
2. An electrically heated steam generator or a gas fired steam generator would be a second option. If you do not have a steam, they are the only alternative.
3. A third alternative would be to use your dirty steam, interrupted by a steam filter. This will purify your steam and has the advantage of drying what is called "wet steam". Unfortunately, the cartridges need to be changed every 6-8 weeks.
Let Consolidated help you solve your tough sterilization problems!
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