Captain,
Have collected some information on disinfection and sterilization. Please plan on spending 30 minutes to go over it:
Historical Importance: Even though the first article does not directly relate to medical equipment sterilization but does play a role to explain the events that led to this field.
Virus X: Tracking the New Killer Plagues Out of the
Present and Into the Future
By FRANK RYAN, M.D.
Little, Brown and Company
The Age of Delusion
Since the days of the cave man, the earth has never been a Garden of Eden, but a Valley of Decision where resilience is essential to survival....
To grow in the midst of dangers is the fate of the human race.
Rene Dubos
Mirage of Health
It is July 30, 1994, and outside a relief tent on the crown of a hill, a child's eyes glaze over and in a terrible moment, all the more disturbing for its seeming banality, he dies. Another child wanders among corpses wailing. His father, who is somewhere nearby, explains in a quiet voice to a reporter with outheld microphone that the child's mother died the day before. The father has another dead baby strapped to his back. The news photographer's camera pans a scene of pitiable desolation, a field of bodies, men and women, old and young, a scattering of colorful African waxes, exposed heads, naked limbs still clutching their pathetic bundle of transportable possessions, all recently dead, the crop of another morning at a Zairian camp for Rwandan refugees called Munigi.
On the evening news, day after day, the affluent world watched as exhausted men threw bodies off the backs of trucks into mass graves. It was a scene, ominous in its portent, that could have been taken from the descriptions of the Black Death in the Middle Ages.
To most people these harrowing events must have evoked a sense of shock, of disbelief. Surely such ancient horrors, the great plagues of history--cholera, tuberculosis, typhoid, bubonicplague--were no more than nightmarish anachronisms. Those old-fashioned men of death might have been a romantic invention, etched in a gothic woodcut by Albrecht Durer: if remotely recalled, it was with a breath of relief that assumed their place on the dusty shelves of history. Suddenly, in these vivid scenes, carried into people's living rooms by the inquisitive eye of television reporting, such perceptions were disturbingly shaken.
Yet it was not so very long ago that the common perception was very different. A few years ago, I visited the parsonage in the village of Haworth, in north Yorkshire, the home of Charlotte and Emily Bronte. I came away with two powerful impressions. The first was the small size of their gloves, which were so tiny they would barely fit the hands of a child today. The second impression was of a fearful mortality. Indeed, the first writer in the family was neither of the women but the unfairly maligned father, Patrick. When Charlotte and Emily were young children, their father was fighting a personal crusade against a mortality that carried away most of his parishioners before they were thirty. Open sewers coursed down the village streets. Half the children died in infancy.
By the turn of the nineteenth century, the mean life expectancy in Britain, as in the United States, Japan, Germany, and all developed countries, was still only forty-five years. Most of the human race still died from infections.
Sometimes this happened dramatically, as in the bubonic plague, which, in its most formidable manifestation, known as the Black Death, fell upon Europe from its origins in Southeast Asia, killing a third, sometimes even half the population of entire countries.
Plagues seemed to attack out of the blue, or retreat in a similar aura of mystery, creating reigns of terror. Why did plagues happen? Where did they come from? Throughout most of our history, people did not know. But there were clues that might be recognized from the behavior of the plagues. Even during the Middle Ages, people looked hard at their deadly patterns, searching desperately for signs, extrapolating reasons. At the height of the Black Death, people recognized the infectious nature of "buboes" that disfigured the bodies of its victims. They also recognized that the hacking, bloodstained cough of plague victims could transmit the deadly contagion to others. The clothes and the bedcovers of the dead were burned and their bodies buried away from society in grotesque charnel pits quickened with lime.
Even the twentieth century has not been immune to Bunyan's so-called men of death. Fulminating epidemics of influenza and typhus scourged the weary population of Europe in the wake of the First World War, inflicting more casualties than all of the carnage. Though there are hieroglyphs from ancient Egypt depicting the typical wasting of limbs that results from poliomyelitis, the epidemic form of this paralyzing illness only emerged in the first half of this century. Even today, in the tragic dystopias of the developing world, the terror so vividly described by Daniel Defoe in his Journal of the Plague Year is apt to return, little altered from when he wrote it, almost three centuries ago.
Dramatically, between the 1940s and the 1960s, the medical and biological sciences discovered many new and effective answers. Thanks to the genius of Paul Ehrlich, the drug treatments of infection had started with salvarsan, used from the early 1900s to treat syphilis. Penicillin, discovered by Alexander Fleming in the late 1920s, was first manufactured for general use in the 1940s. Prontosil rubrum, the sulphonamide prototype discovered in Germany by Domagk, Klarer, and Mietzsch, had by then been generally available since 1935. Stimulated, ironically, by the military objectives of the Second World War, science had entered a new era of enlightenment that has been termed "continuous revolution." In 1943 the two antituberculosis drugs, streptomycin and para-aminosalicylic acid (PAS), were simultaneously discovered by, respectively, Waksman and Schatz in America and Lehmann and Rosdahl in Sweden.(1) These were quickly followed by a proliferation of further antibacterial discoveries, including Hubert Lechevalier's neomycin,the first antifungals, the cephalosporins, and the macrolides. Every known bacterial infection became treatable.
On all fronts, the biological and medical sciences, and the applications that derived from them, had entered a stage of acceleration more dramatic than had ever been seen before.
And even those most refractory infections of all, those caused by viruses--formerly dismissed as untreatable because viruses disappeared into the inner labyrinths of the living cells, merging into the very genomes--were becoming amenable to early treatments: idoxyuridine, designed as an anti-DNA metabolite, proved useful for herpes simplex infections, as did virugon for influenza; methisazone, derived from Domagk's thiosemicarbazones, was showing potential in the treatment of early smallpox. A new front line of antiviral drugs--the interferons, based on the body's own antiviral mechanisms--seemed to harbor exceptional promise.
The global spirit of optimism that followed was aptly summed up in a speech made by U.S. President Richard Nixon before Congress in 1971. "I would ask for an appropriation of $100 million to launch an intensive campaign to find the cure for cancer.... The time has come in America when the same kind of concentrated effort that split the atom and took man to the moon should be turned towards conquering this dread disease."
Gone was the fear of infection. In declaring war on cancer, President Nixon was no more than iterating the zeitgeist of popular medical and lay opinion. On December 4, 1967, Dr. William H. Stewart, the U.S. Surgeon General, informed a meeting of state and territorial health officials that infectious diseases were now conquered. Under the umbrella of "A Mandate for State Action," he extolled the findings of the Centers for Disease Control a year earlier. Epidemic diseases such as smallpox, bubonic plague, and malaria were things of the past. Typhoid, polio, and diphtheria were heading in the same direction.
While syphilis, gonorrhea, and tuberculosis were not quite so readily defeated, it was only a matter of time before every plague that had ever struck fear into the heart of decent Americans would be a distant memory. Cervical cancer was listed as one of the diseases
that could be brought under effective control. Even cancer, it seemed, would be quickly solved. All that was needed was the money to cate the intellects of scientists.
In such a climate of optimism, Stewart urged the experts to focus the lion's share of health resources onto the "new dimensions" of ill health, the problems that would face the space age: chronic diseases.(2) Confidence was brimming over. It was as if in a single intoxicating summer, humanity had convinced itself that winter would never come.
Since 1960, when global war was declared against the disease, tuberculosis, which had killed roughly three quarters of a billion people in the century and a half up to 1960, was being beaten back on all fronts. Year by year, as a result of a massive and coordinated campaign, in America, in England, Europe in general, in Japan, and even Russia, its prevalence was declining. But it was never an easy victory. The battle still harnessed great expenditures of ingenuity, money, and manpower. Nevertheless, it seemed just a matter of time before those same methods that had worked for affluent countries would be put into effect to bring down the horrific death rate from tuberculosis throughout the developing world, where a staggering 3 million people were still dying from the disease each year.
Malaria, second in line for the distinction of greatest killer among the infections, was responding dramatically to antimalarial drugs, drug prophylaxis, and efforts at mosquito control. Plans were formulated, the banners aloft, for two of the greatest plagues that had afflicted humanity to be wiped off the face of the earth. Similar hopes existed for poliomyelitis, the plague that paralyzed children. Thanks to Albert B. Sabin's brave initiative with live virus coating sugar lumps, paralytic poliomyelitis was largely eradicated in the developed world. Triple vaccine was reducing the incidence of tetanus, whooping cough, and diphtheria to such low levels that young doctors might not see a case throughout the years of their training. Measles vaccine would soon be added.
These planners did not perceive themselves as overly optimistic. On the contrary, they were imbued with certainty, based on a sound understanding of the microbes they were battling and on the most up-to-date results of vaccine development, epidemiology, and
antibacterial drugs. So, in a broad front of what amounted to a clandestine third world war, the men of death of the medieval imagination were being faced on the battlefield, beaten back, in some instances would soon be dead and buried.
When it came to plague viruses, none had ever caused such a fearful global mortality as smallpox. Believed to have originated in India in ancient times before first ravaging the Roman world as early as A.D. 165, since then it had scourged humanity in what amounted to a permanent pandemic, causing incalculable loss of life and misery through morbidity and disfigurement.(3) In its more virulent form caused by the virus Variola Major, it still caused up to 50 percent mortality in its victims. In 1958, when Russian doctors pressed for a concerted world campaign against it through the World Health Organization, 2 million people still died from its effects each year. The resultant global campaign against smallpox began in 1967, involved the vaccination of as many as 250 million people yearly, and was led by the tenacious American physician Donald A. Henderson. After ten years of backbreaking struggle, pressing to isolate cases and vaccinate populations through famine and war zones, success was finally announced in 1977. It was a remarkable achievement to match that of the defeat of tuberculosis, the realization of a hitherto impossible human dream. But it fueled a growing hubris among scientists. If we could eradicate smallpox, we could eradicate all of the viral plagues as well.
A certain vainglorious spirit of celebration was surely understandable. There was universal hope for the advance of human civilization. Other more subtle wars had been fought in real, philosophical, and sociological fronts against a historical legacy of tyranny, and those wars had, in part or in whole, been won. Outmoded despotic arrogance had been supplanted by a democratic spirit of emancipation, which, though led by Western enlightenment, was rapidly disseminating throughout the world. Civil rights and sexual liberation went hand in hand with the new expectation of health. In developed countries families condensed to the nuclear 2.2 average number of children: liberated from the fear of epidemics, women could make full use of the newly available systems of birth control to facilitate their own emancipation. The same generation that had created hydrogen bombs, jet air transport, and rockets to take men to the moon had every reason for optimism. While that spirit and courage might, in retrospect, appear naive, it was also laudable.
To them their aims were not unreasonable and they fought very hard to achieve them. It is tragic that their lofty ideals were not altogether realized. Perhaps it reflected, in part, a regrettable separation of clinicians from basic scientists.
In fact those people whose living depended upon a study of microbes, of their potential and durability, were never deluded. A prescient few, such as Rene Dubos, warned us openly that the optimism was unjustified.(4) But on the whole people were not inclined to
listen. Most doctors, never mind members of the public, were infected with the prevailing overconfidence, hardly perceiving the growing threat of social changes inherent to the "global village." They seemed unable to grasp the new potential afforded to a very ancient peril arising from world travel. Diseases that once took months to cross the Atlantic with Columbus or the Pilgrim Fathers could now circumnavigate the globe in a single day.
Today, as one after another of the dismissed plagues returns to haunt us, as new plagues every bit as deadly as anything seen in previous history threaten our species, it is obvious that the postwar years were an age of delusion. It was comforting, a very understandable delusion, but a delusion nevertheless.
Prior to 1950, device sterilization was largely the responsibility of the medical practitioner's staff or the hospital's entral supply departement. Medical devices, primarily made of metal, were not adversely affected by dry heat,steam or chemical sterilizing solutions. These procedures, however, were not always effective. The term "nosocomial infection" was coined to describe infections caused by hospital procedures. Widespread studies indicate that their incidence rate was alarmingly high.
Present:
In today's world, the need for infection control has never been greater. The most effective way to prevent the spread of infection is proper use of sterilization equipment. This includes steam, dry heat, chemical sterilization including Sterox and Ster-O3-Zone.
Sterilizers are recommended by health care professionals world wide including the World Health
Organization (WHO) and the Centers for Disease Control (CDC), USA. Disease-causing microbes, some of them impervious to antibiotics, may inadvertently be carried from patient to patient by health-care workers who only touched surfaces in the room of an infected person, say scientists at a meeting of the American Society for Microbiology.
"Since 1989, we've seen the emergence and rapid dissemination of strains of enterococci (bacteria that infect the intestines) resistant to most of the antibiotics available," says John M. Boyce, professor of medicine at Brown University, Providence, R.I.
Drug-resistant staphylococcus aureus, bacteria that can cause illnesses ranging from skin boils to pneumonia, also have been of growing concern, he says. "Even though hospitals have had policies designed to help prevent the spread of these, we continue to see them more and more commonly."
Infected patients, even those who don't get sick from these organisms and are not known to be infected, can "shed" the microbes onto sheets ( A killer for the Laudry boys), bed rails and other surfaces, he says. "The consensus has been for years that those kinds of contaminated equipment items probably resulted in very little transmission to other patients," he says, but new studies
"suggest maybe we need to worry more about the environment."
He says tests found drug-resistant bacteria on gloves worn by health-care workers who touched room surfaces but not the infected patients. "Their gloves or hands would not look soiled," he says. The study shows "in circumstances of heavy contamination, health-care workers can spread (bacteria) to another patient if they don't wash their hands."
Hospital outbreaks have been traced to electronic thermometers, improper ventilation systems and water sources such as sinks, showers, tubs and flower vases, says David Jay Weber, University of North Carolina, Chapel Hill. Transmission can be prevented through strict infection control procedures, but more research is needed to determine what measures are most effective.
"The infection has to get from somewhere to the patient," Weber says. "If we know the routes, we can take steps to preclude it."
STERILIZATION OR DISINFECTION OF MEDICAL DEVICES:
GENERAL PRINCIPLES
The following principles are applicable to most questions CDC receives about sterilization or disinfection of patient-care equipment. However, these statements are not comprehensive.
1.In general, reusable medical devices or patient-care equipment that enters normally sterile tissue or the vascular system or through which blood flows should be sterilized before each use. Sterilization means the use of a physical or chemical procedure to destroy all microbial life, including highly resistant bacterial endospores. The major sterilizing agents used in hospitals are a) moist heat by steam autoclaving, b) ethylene oxide gas, and c) dry heat. However, there are a variety of chemical germicides (sterilants) that have been used for purposes of reprocessing reusable heat-sensitive medical devices and appear to be effective when used appropriately, i.e., according to manufacturer's instructions. These chemicals are rarely used for sterilization, but appear to be effective for high-level disinfection of medical devices that come into contact with mucous membranes during use (e.g., flexible fiberoptic endoscopes). 2.Disinfection means the use of a chemical procedure that eliminates virtually all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial endospores) on inanimate objects. There are three levels of disinfection: high, intermediate, and low. High-level disinfection kills all organisms, except high levels of bacterial spores, and is effected with a chemical germicide cleared for marketing as a sterilant by the Food and Drug Administration. Intermediate-level disinfection kills mycobacteria, most viruses, and bacteria with a chemical germicide registered as a "tuberculocide" by the Environmental Protection Agency (EPA). Low-level disinfection kills some viruses and bacteria with a chemical germicide registered as a hospital disinfectant by the EPA.
3.Heat stable reusable medical devices that enter the blood stream or enter normally sterile tissue should always be reprocessed using heat-based methods of sterilization (e.g., steam autoclave or dry heat oven). 4.Laparoscopic or arthroscopic telescopes (optic portions of the endoscopic set) should be subjected to a sterilization procedure before each use; if this is not feasible, they should receive high-level disinfection. Heat stable accessories to the endoscopic set (e.g., trocars, operative instruments) should be sterilized by heat-based methods (e.g., steam autoclave or dry heat oven).
5.Reusable devices or items that touch mucous membranes should, at a minimum, receive high-level disinfection between patients. These devices include reusable flexible endoscopes, endotracheal tubes, anesthesia breathing circuits, and respiratory therapy equipment.
6.Medical devices that require sterilization or disinfection must be thoroughly cleaned to reduce organic material or bioburden before being exposed to the germicide, and the germicide and the device manufacturer's instructions should be closely followed.
7.Except on rare and special instances (as mentioned below), items that do not ordinarily touch the patient or touch only intact skin are not involved in disease transmission, and generally do not necessitate disinfection between uses on different patients. These items include crutches, bedboards, blood pressure cuffs, and a variety of other medical accessories. Consequently, depending on the particular piece of equipment or item, washing with a detergent or using a low-level disinfectant may be sufficient when decontamination is needed. If noncritical items are grossly soiled with blood or other body fluids, follow instructions outlined in the section on HIV-related sterilization and disinfection of this information system. Exceptional circumstances that require noncritical items to be either dedicated to one patient or patient cohort, or subjected to low-level disinfection between patient uses are those involving 1.Patients infected or colonized with vancomycin-resistant enterococci or other drug-resistant microorganisms judged by the infection control program, based on current state, regional, or national recommendations, to be of special or clinical or epidemiologic significance
or 2.Patients infected with highly virulent microorganisms, e.g., viruses causing hemorrhagic fever (such as Ebola orLassa).
TB spread by dirty instruments ( An Interesting article)
Hospitals didn't follow proper cleaning procedures
Tuberculosis germs are easily spread by close contact with an infected patient, necessitating strict hospital procedures.
By Charlene Laino
MSNBC
Dirty hospital instruments are responsible for at least two recent outbreaks of tuberculosis, two separate teams of researchers reported .In each case, the germs from a TB patient were carried on the dirty instruments, infecting others treated with the same devices. Even if only 10 percent of bronchoscopes are contaminated,about 460 to 2,300 people might be exposed to disease-causing viruses each year.
Medical college Virginia BLAME FOR TWO recent TB outbreaks goes to hospital personnel who failed to follow national guidelines for cleaning and disinfecting the long tube-like devices used
to examine the lung's airways known as bronchoscopes, researchers said. The outbreaks were uncovered after intensive medical detective work, with DNA fingerprints pinning down the culprits.
In one case, scientists at Johns Hopkins and the Maryland State Department of Health and Mental Hygiene in Baltimore found identical DNA fingerprints in bacterial cultures isolated from two TB patients. Since the TB cases were detected six months apart, a link between the two sources was unsuspected until DNA fingerprinting revealed a perfect match, said study head Dr.
William Bishai, an assistant professor of molecular microbiology and immunology at Johns Hopkins. But the two patients lived in different cities, worked in different places and had no other previous contact with each other, he said.
After pouring over the patients' medical records, the researchers realized that the only link between the two patients was the hospital where they both had been bronchoscoped - with the same instrument, in the same operating room. Subsequent study showed that the hospital had not
adequately cleaned and disinfected the bronchoscopes, Bishai said. About 460,000 patients undergo bronchoscopy each year in the United States.
In the second case, Tracy Agerton at the Centers for Disease Control and Prevention in Atlanta studied eight South Carolinians with a rare, drug-resistant TB strain with
identical DNA fingerprints. Five were family members or close friends, Agerton said, confirming close contact and normal transmission by air. But in the other three patients, the hospital bronchoscope was again the only common thread.
Both studies appear in this week's issue of the Journal of the American Medical Association. "The key message is that hospitals and clinics cannot afford to trivialize the importance of routine and thorough cleaning of reusable parts of the bronchoscope," Dr.Wenzel said. "Strict protocols for routine and appropriate chemical disinfection or sterilization must be incorporated into a hospital's infection control plan."
Solutions :
The solution to this problem was provided by the disposable medical product industry. Single use device, procedure kits and trays were produced and packaged to maintain product sterility up to the point of use. Two new technologies contributed to this development:
The development of low cost biocompatible plastic resins with physical characteristics appropriate for medical devices and their packaging.
The discovery that both gas fumigation and gamma radiation could be used as effective low-temperature sterilizing methods.
Initially, the most economical and adaptable method involved gas fumigation using ethylene oxide (EtO). Gas chambers of various sizes were designed for use by physicians' offices, hospitals and device manufacturers. While their capacities were limited, additional chambers could be added as the need arose. The cost of the gas itself was relatively low, and its toxic and carcinogenic characteristics were not yet fully known. Conversely, gamma sterilization equipment required very large financial investments. Thus, its use was confined to only the very large manufacturers whose product throughput was great enough to justify the cash outlays required for a large-scale gamma facility.
One manufacturer, Johnson & Johnson, decided to make these investments for sutures and other products and went on to develop many of the techniques and controls that were to later prove appropriate for the widespread use of gamma sterilization.
Sterilzation Methods
Autoclave
Autoclaves are vessels, usually made of metal, that are able to withstand very high temperatures and pressures. Instruments are sterilized by being placed in water in an autoclave and heating the water above its boiling point under pressure. Autoclave is the sterilization method used in most hospitals and other institutions that require the removal of microbial organisms from instruments. Autoclave is ideal for metal instruments. However, many of the polyethylene were unable to withstand the high temperature and pressure conditions.
Ethylene Oxide
Initially, ethylene oxide (EtO) was the low temperature sterilization method of choice. Gas chambers of various sizes were designed for use by physicians' offices, hospitals, and device manufacturers. While their capacities were limited, additional chambers could be added as the need arose. The cost of the EtO gas was low, and its effectiveness as a sterilant was better than autoclave sterilization. It appeared to be a viable solution to the problem of low temperature sterilization.
As the use of EtO grew through the industry, its characteristics became better known and defined. Its use as a sterilant was limited.
1.EtO is only useful as a surface sterilant. It is unable to reach blocked-off surfaces, such as
those found in hypodermic plunger/barrel interfaces in hypodermic needles.
2.EtO requires careful and simultaneous control of six variable but interdependent parameters:
gas concentration, vacuum, pressure, temperature, relative humidity, and time of exposure.
These considerations become secondary when discussing the potential effect of EtO on workers and patients. Initially, it was thought that
Initially, it was thought that EtO was so volatile that it was incapable of leaving a residue on treated products. However, it was discovered that EtO reacts with moisture and chloride ions to form ethylene glycol and 2-cholorethanol, a non-volatile toxic residue. Beginning in 1968, studies performed with both human and animal subjects verified EtO's potential to be toxic, carcinogenic, and mutagenic (SteriGenics). For these reasons, EtO is now used on radiation sensitive materials, such as custom procedure kits containing unit dose drugs contained hermetically sealed packages.
Gamma Radiation
Gamma rays, high energy, neutrally charged electromagnetic waves, are emitted from a Cobalt 60 or Cesium 137 source encapsulated by a double layer of stainless steel to prevent the escape of radioactivity to the environment. The devices to be sterilized are placed near the emitting source until they have been exposed to the required amount of radiation. No radiation is "absorbed" by the devices (that is, they are not radioactive after sterilization), so they can be used immediately after sterilization.
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