A Practical Guide to Decontamination in Healthcare

Gerald E. McDonnell, Denise Sheard

• Publisher: Wiley-Blackwell
• Year: 2012
• ISBN:
  9781118321317
• Edition: 1
• Topic: Medicine
• Subtopic: Infectious Diseases

Prevention is the first line of defence in the fight against infection. As antibiotics and other antimicrobials encounter increasing reports of microbial resistance, the field of decontamination science is undergoing a major revival. A Practical Guide to Decontamination in Healthcare is a comprehensive training manual, providing practical guidance on all aspects of decontamination including: microbiology and infection control; regulations and standards; containment, transportation, handling, cleaning, disinfection and sterilization of patient used devices; surgical instrumentation; endoscopes; and quality management systems.

Written by highly experienced professionals, A Practical Guide to Decontamination in Healthcare comprises a systematic review of decontamination methods, with uses and advantages outlined for each.Up-to-date regulations, standards and guidelines are incorporated throughout, to better equip healthcare professionals with the information they need to meet the technical and operational challenges of medical decontamination.

A Practical Guide to Decontamination in Healthcare is an important new volume on state-of-the-art decontamination processes and a key reference source for all healthcare professionals working in infectious diseases, infection control/prevention and decontamination services.

1 Introduction

What is decontamination?

First “to do no harm”
Of the Epidemics, Hippocrates ∼400 BC)

Health is an important subject to all. It affects us as ­individuals, our families and the communities in which we live. Our health is improved by promoting well-being and preventing disease or other negative health impacts. A disease may be defined as any effect that impairs/harms the body’s normal function and therefore has an impact on our health (mild, moderate or even severe). Diseases can be infectious or non-infectious (such as cancer, effects of drug abuse, stress, chemicals, etc.). Infectious diseases are a leading cause of sickness and death worldwide. They are caused by living creatures that cannot be seen by the naked eye, known as “microorganisms”, such as viruses and bacteria. It is estimated that infectious ­diseases affected our breathing, digestive and immune systems are responsible for ~17% of human death worldwide (the next highest cause of death is coronary heart disease at ~12%). These rates are estimated across the whole world, but are even higher in lower income regions. Examples of health efforts to reduce these risks in the general public include improving drinking water quality (chemical and microbiological), immunization (vaccination), and safe handling/disposal of waste. Many of these efforts influence our daily lives, but the risk of infectious disease significantly increases when we are sick or when our bodies are otherwise compromised (e.g. when undergoing a surgical procedure). For these reasons, healthcare institutions (such as hospitals and clinics) have many procedures and practices in place to control the spread of infectious disease within these facilities, and to protect patients, staff and the general public. It is an important philosophy in medical practice: First “to do no harm” or in Latin “primum non nocere”. These are collectively referred to as “safe” or “infection control/prevention” practices that prevent the spread of disease or other negative effects from one patient to another (or to/from staff or visitors within these ­facilities). These practices include:

• Immunization
• Isolation of patients with specific diseases
• Decontamination of equipment and various surfaces

As “contamination” refers to something being “dirty” or “soiled”, “decontamination” is the means to render it safe for handling, use or disposal. Dirt or soil may include things like dust, patient materials (such as blood, feces, various tissues from surgical procedures, etc.) and associated microorganisms that can cause disease. In this book, the terms “decontamination” and “reprocessing” are used interchangeably. In healthcare facilities a variety of physical and/or chemical products or processes are used for decontamination. These include:

• Cleaning, the removal of soil to make something “clean”
• Disinfection, the antimicrobial reduction of micro­organisms; other widely used terms that refer to disinfection can include antisepsis, pasteurization, sanitization and fumigation
• Sterilization, the complete eradication of all microorganisms

These are all methods of decontamination and are explained further in this book. Examples of specific decontamination practices will include:

• Hand and skin hygiene, including routine hand ­disinfection and preparation of the skin for a surgical procedure
• Taking surgical or medical instruments that have been used on one patient and decontaminating them in ­preparation for use on another
• Cleaning and disinfection of linens or other materials (including patient bed sheets, sterile towels and cottons fabrics)
• Disinfection of water for drinking or sterilization of water for injection use
• Cleaning and disinfecting environmental surfaces such as floors and beds
• Sterilization of contaminated waste materials for safe disposal (including incineration)

In some cases decontamination is a one-step process, for example sterilization of contaminated waste materials, but is most often a two-step process to include cleaning (the physical removal of soil) and disinfection or steri­lization (as the antimicrobial process to inactivate the various types of microorganisms that we cannot see). For re-­usable medical and surgical instruments this will normally include at least cleaning and disinfection, but will often include sterilization, this being the highest level of safety. Decontamination is therefore an integral part of infection prevention and should not be underestimated.

A brief history of decontamination

It is clear from many ancient documents that decontamination practices have been considered to have health ­benefits. Examples include:

• In approximately 1400–1200 BC (estimated to be at the time of Moses), a sanitary code was outlined in the Leviticus, Numbers and Deuteronomy chapters of the Bible. It was noted even at this time that when dealing with disease that hands should be washed under running water and that there was a value in boiling water to make it safe for drinking or other purposes.
• The Eber’s Papyrus, a medical document from about 1500 BC, describes a method of combining animal and vegetable oils with alkaline salts to form a soap-like material used for treating skin diseases, as well as for washing hands.
• The world’s oldest known medical text outlines the procedures for wound management practiced by the Sumerians (∼2000 BC). The wound was cleansed with beer (which contained alcohol) and then bandaged with a cloth soaked in wine and turpentine. The practice of using alcoholic beverages and turpentine would remain the treatment of choice until the modern era.
• Similar examples of wound, water or air treatments have been described by the ancient Greek and Roman cultures. Aristotle (384–322 BC), a Greek philosopher, even described boiling to treat water. Homer (∼850 BC), in his epic poem the Odyssey, described the use of sulfur as an area disinfectant.
• Ancient methods of preserving foods from rotting ­during storage (which we now know is caused by microorganisms) included drying, heating and use of sugar or vinegar.

From these ancient times to the 19th century, infection was a major cause of mortality and morbidity in humans. It would take many thousands of years for the microbiological origin and transmissibility of infection to be discovered. A recurring theme in history was the belief that epidemic diseases were spread by something in the air. Hippocrates (460–370 BC) was an ancient Greek doctor and is often referred to as the father of medicine, being still referred to today by new doctors taking the Hippocratic oath. He put this belief into practice when attempting to drive the plague (now know to be a bacterial disease) from Athens by lighting fires of aromatic wood in the streets. This belief that diseases were spread by something in the air continued throughout history.

Many ancient physicians well understood that when the skin was broken in any way (by a wound or during attempts at surgery) the risks of “bad” things happening was significantly increased. It was unknown at the time that wound infections were caused by various types of microorganisms, particularly bacteria, with dramatic consequences, including destruction of limbs and death. Infections in such cases of skin damage were the major contributor to death and suffering, which is why surgical procedures were attempted only as a last resort. Through the ages operations were performed with little regard for a “clean” environment. Surgeons’ hands, rarely washed, were placed directly into the patient’s wounds. Frequently, onlookers were encouraged to “take a feel” for educational purposes. Surgical instruments used in such procedures were crudely wiped, placed back into their velvet carriers, and re-used, some having been sharpened on the sole of the surgeon’s boot. The floors of the surgical wards were covered with whatever came from the patient, which could include feces, urine, blood and pus, and hygiene practices in other areas of such facilities (if indeed dedicated facilities where used) at the time were also unknown. Not surprisingly, surgical site infection was the major contributor to morbidity and mortality rates, occurring after practically all operations and taking the lives of almost half of all surgical patients.

Hippocrates was one of the first recorded to hold an opinion on the cause of such problems, stating that the formation of pus (suppuration) was not a natural part of the healing process and should be avoided. His ­recommendations for managing wounds were: cleansing with wine, applying a bandage, and then pouring wine on the bandage. Another Greek physician Claudius Galen (∼AD 130–200) recommended soap for both medicinal and cleansing purposes. He, however, disagreed with Hippocrates, that the formation of pus was not a normal occurrence; he believed that pus was essential for wound healing. It is often considered that this was originally an Arabic idea. Suppuration was actively encouraged by ­surgeons in traumatic and painful procedures. This dis­agreement would continue to be debated for centuries.

One thousand years later, the Italian Theodoric Borgognoni (1205–1298) challenged Galen’s view of suppuration. He dedicated his career to finding the ideal conditions for wound healing and became one of the most famous surgeons during the Middle Ages. He argued that a wound should be maintained clean and closed (sutured) to control infection (and preserve life). Because his views were contrary to the established teachings, he was denounced by his colleagues and even by the church. Indeed, the surgeon would often welcome the signs of suppuration, depending on how it looked. Wounds were classified into two categories: those with suppuration and those without. Wounds with “laudable pus” (a creamy yellow ooze) tended to run a chronic course, taking months to heal, but the patients were generally free of other negative signs and did not die! Wounds with a thin, watery discharge were associated with a fatal outcome, with the patient dying of sepsis within days. It is not, therefore, surprising that even the most conscientious surgeons preferred and even encouraged the formation of pus. Galen’s doctrine of suppuration would remain the rule for wound management until the late 19th century.

In addition to wound infection, general standards of public hygiene and their impacts on public health were not widely appreciated. As an example in Europe, following the eventual fall of Rome in AD 467 many simple hygiene practices were neglected. Examples included a decline in bathing habits, lack of personal cleanliness and unsanitary living conditions (lack of waste disposal, etc.). It is well appreciated that such conditions contributed heavily to the great plagues of the Middle Ages, and especially to the Black Death of the 14th century. At the same time, it was understood that contact with sick individuals could rapidly spread a disease, as highlighted by the fear associated with bacterial diseases such as leprosy and bubonic plague; in fact, infected bodies have been used over the ages as effective weapons in battles and sieges! Equally, infected bodies and materials were often dealt with by burning (incineration).

Hieronymus Fracastorius (1478–1553) suggested that the cause of infectious disease was from invisible living “seeds” (seminaria contagionum). He even at this period described three modes of disease spread: direct contact with infected persons, indirect contact with fomites and airborne transmission. Ambroïse Paré (1510–1590), ­considered one of the fathers of modern surgery, believed that infection was introduced from the environment. In 1625 Francis Bacon described some methods to prevent or control wound infections, such as by the use of salt or excluding air. In the 1670s Anton van Leeuwenhoek was the first microbiologist to observe individual, live microorganisms, by using a simple microscope. He called these animalcules or “little animals”. He also described the first direct evidence of disinfection in observing the death of animalcules treated with pepper (in water) or vinegar. Similar disinfection studies were described shortly after by Edmund King and John Pringle. It could be argued that this was the start of the modern era of understanding infectious diseases and their control, but even then the “microbial theory” remained debated for the next few centuries.

In the meantime, the benefits of disinfection practices continued to be better understood. Ancient disinfection methods had been previously recognized, such as the benefits of storing water and other liquids in copper or silver vessels (as a preservative method from the release of copper or silver into the water), burning with fire (as a method of incineration) and boiling water. In the modern era further advances where made such as:

• In 1680 Dennis Papin developed the first recognizable steam generating machine.
• In 1774 Scheele discovered chlorine and its antimicrobial effects.
• In the 1830s William Henry published studies on the “disinfection power of increased temperatures”.
• In the mid-1800s copper sulphate, zinc chloride and sodium permanganate, acids, alkalis, sulfurs and alcohols were recognized as disinfectants.

In the late 1840s, Dr Ignaz Semmelweis, whilst working in the maternity wards of a Vienna hospital, observed that the mortality rate in a delivery room staffed by medical students was up to three times higher than in a second delivery room staffed by midwives. Expectant mothers were terrified of the room staffed by the medical students! Semmelweis observed that the students were coming straight from their lessons in the autopsy room to the delivery room. He believed that they were carrying infectious agents from the lab to their patients. When he implemented a hand washing protocol at the hospital the mortality rate dropped to less than 1%. Today, he is ­recognized as the father of hand hygiene, one of the most important measures to be taken by healthcare practitioners to reduce cross-contamination. Due to the lack of indoor plumbing at the time, it was difficult to get water to wash hands, making this an unpopular idea. In order to make the water comfortably warm, it would have to be heated over a fire. Besides, contact with water was associated with diseases such as malaria and typhoid fever. Unknown to him, similar results had been described a few years previously by the American scientist Oliver Wendell Holmes. Both suggestions fell on deaf ears. Semmelweis, for his efforts, was committed to an asylum and died of a blood infection.

Despite the earlier work by others such as van Leeuwenhoek, the prevailing theory at the time was known as “spontaneous generation”. This is often ­originally attributed to the Greek philosopher Aristotle (384–322 BC) and simply regards the origins of life as being from inanimate matter or non-living substances. Many famous names in the modern history of infection control, such as Pouchet, Nightingale and Virchow ­subscribed. Louis Pasteur was born in 1822 in France and in 1857 he proposed the “germ theory of disease”, which is regarded as one of the most important dis­coveries in decontamination history. The theory proposed that most infectious diseases are caused by germs; he also ­specifically described the existence of bacteria. In the 1860s Pasteur commenced his anti-spontaneous g...