Week 4 Chapter 9 infection preventioin and control Flashcards
bacteria
Bacteria are unicellular microorganisms that can be spherical (cocci, meaning “berry”), rod shaped (bacilli, meaning “little staff”), spiral (spirochetes, which are corkscrew shaped), or comma shaped (vibrios, curved rods), which can grow together to form S shapes. Bacteria can reproduce by cell division about every 20 minutes, giving them the ability to develop huge numbers very quickly. Some also have the ability to produce a highly resistant form known as an endospore. This is a resting, nonactive state. Because they are not active (i.e., not reproducing or metabolizing), endospores have no activity to be disrupted by a chemical or physical agent. Therefore, they are extremely resistant to much of the environment, to chemical agents, and to physical procedures applied to them. Bacteria can remain viable for years and then germinate when the environment becomes favorable to them. Some bacteria are capable of producing an endotoxin that is toxic to mammals. This endotoxin is responsible for producing the high fevers associated with a bacterial infection.
biohazard
Contaminated Waste Disposal
The hospital should have policies and procedures for disposing of all items. These are not optional; such policies are regulated by both OSHA and the EPA. Some departments may require the separation of glass, plastic, and paper into clearly labeled, covered containers, whereas others may place all disposable items in the same bag or box. Recent regulations demand that objects contaminated with blood or body fluids be discarded in a suitable container and marked with the biohazard symbol (Fig. 9-3). If your department does not have a written set of procedures, you should inquire about them.
disinfection
“Sterilization and Disinfection
Standard sterilization and disinfection procedures for patient-care equipment currently recommended for use in a variety of health-care settings—including hospitals, medical and dental clinics and offices, hemodialysis centers, emergency-care facilities, and long-term nursing-care facilities—are adequate to sterilize or disinfect instruments, devices, or other items contaminated with blood or other body fluids from persons infected with blood-borne pathogens including HIV.
Instruments or devices that enter sterile tissue or the vascular system of any patient or through which blood flows should be sterilized before reuse. Devices or items that contact intact mucous membranes should be sterilized or receive high-level disinfection, a procedure that kills vegetative organisms and viruses but not necessarily large numbers of bacterial spores. Chemical germicides that are registered with the U.S. Environmental Protection Agency (EPA) as “sterilants” may be used either for sterilization or for high-level disinfection depending on contact time.”
fomite
Mode of Transport
There are four main routes of transmission for infection, as follows:
Fomite (indirect contact). An object that has been in contact with pathogenic organisms is a fomite. Think about what might be a fomite in the radiology department: the x-ray table, the CT or MRI patient couch, the chin rest on the chest board, the calipers, positioning sponges, the ultrasound transducer, the gamma camera surface, a mishandled syringe or needle, or even the patient’s chart. The worst (and most often forgotten) fomite is the pillowcase not changed after each patient.
People have no idea how often they touch different things without thinking. Certainly, microbiologists and infection control specialists understand the role that hands play in transferring infection from one person to another. It is not only about self-protection, but also about protecting the next person or patient contacted. Careless technique can increase patient-to-operator contamination as well as patient-to-patient contamination. Studies have shown that people, especially health care workers, are not diligent about washing their hands after bathroom use. Contemplate the number of patients and staff using the restroom each day. Just how clean is that “exit” door handle?
fungi
Fungi (Eumycetes) are familiar in many forms and sizes, such as lichen, mushrooms, toadstools, puffballs, molds, and yeasts. Some of these are pathogenic (disease causing). Some nonpathogenic forms may be equally dangerous because of allergic reactions. Fungal diseases are called mycoses; the drug Mycostatin (nystatin) is used as an antifungal agent (myco, fungal; statin, stopping reproduction). Fungi live on dead or decaying matter, need an abundant amount of moisture and oxygen, and grow best at room temperature. Warm, humid environments will accelerate their growth, and they grow well in environments that contain sugar or are slightly acidic. Fungi reproduce through spore formation, which is more like seed production than the types of bacterial spores discussed earlier. Aside from their negative effects, fungi are also widely used industrially for such products as antibiotics, cheese, bread, beer, and wine.
hepatitis B virus (HBV)
In addition, these patients may be exposed to particularly virulent strains of microorganisms. Staphylococcus aureus is an example of a relatively benign microbe evolving into a deadly threat. One of the most life-threatening infections is a hospital-acquired staphylococcal (“staph”) infection. These organisms have been so exposed to antimicrobial agents that they have mutated into strains that are resistant to chemical agents. One can sterilize equipment that is contaminated, but one cannot sterilize a patient’s arm. These hospital-acquired infections are called nosocomial. They also pose a threat to health care workers. Thousands of health care workers are infected with the **hepatitis B virus (HBV) **each year; as many as 2% of those infected die. This particular strain of hepatitis is highly infectious, requires intensive treatment, and may lead to lifelong health problems. In 1991 the Occupational Safety and Health Administration (OSHA) published regulations requiring health care employers to provide HBV immunizations to employees, as well as procedures and equipment to prevent the transmission of HIV and other bloodborne diseases to which employees are exposed. There is also a strain labeled hepatitis D that “piggybacks” on HBV. The most distressing fact is that hepatitis B is preventable with immunization, and therefore hepatitis D is also preventable. No health care worker should be without this immunization.
DID YOU KNOW?
host
Viruses are perhaps the simplest form of life. They cannot live outside a living cell because they are missing some of the components absolutely necessary for their own reproduction. Viruses use the organelles and metabolic functions of the host cell to produce new viruses. When the reproduction phase is complete, the new viral particles are released from the host, often by bursting the host cell, which leads to cell death. One of the interesting properties of viruses is that they must find a compatible receptor site on the host cell. Have you ever had a cold sore? This lesion is caused by herpes simplex, a virus. The interesting fact is that herpesvirus is found on soft tissue that is not attached to bone. One can have herpes lesions on the lips, face, or genital mucosa, but they do not appear on the gum tissue that covers the bone, even though this tissue is exposed to millions of virulent viral cells. The reason is because there are no compatible receptor sites. There are two major medical concerns about viruses: (1) the limited pharmacotherapeutic drugs available and (2) the ability of viruses to mutate. Our advanced medical field still depends predominantly on the patient’s own immune system to fight viral infections
human immunodeficiency virus (HIV)
The first known case of HIV was in 1959, but the medical community as a whole did not really become aware of HIV until the late 1970s or early 1980s. Rare types of pneumonia, cancer, and other diseases were being reported in disproportionate numbers in California and New York among homosexual men. The condition was first labeled acquired immunodeficiency syndrome (AIDS) because of the conditions being observed. Opportunistic infections such as Kaposi’s sarcoma and Pneumocystis carinii pneumonia were increasing. Microorganisms that did not cause an infection in healthy people were causing death in persons with a compromised immune system. The virus reduces the host’s resistance to infection because it destroys T lymphocytes (infection-fighting cells). The progression of HIV is a story of irony. In brief, T lymphocytes are the body’s defense against infection. The AIDS virus uses the T lymphocyte as its host cell to replicate. When the virus is released, the T cell dies. More new virus in the blood signals the body to send more T cells. The additional T cells provide more places for the AIDS virus to replicate. The T cells are supposed to kill the virus, but the virus uses the T cells to reproduce and then kills the T cell.
The term AIDS is now used to refer to the stage when persons who are HIV positive have developed additional illnesses from opportunistic microorganisms. In 1982 the virus was discovered and initially named “HTLV” (human T cell lymphotrophic virus). The name was later changed to HIV. In 1999, international scientists reported tracing the origin of HIV to a single virus found in a subspecies of equatorial West African chimpanzee.
To clarify terminology, “HIV” is the name of the virus. Persons who have positive results from blood tests for HIV are “HIV positive.” In recent years, there have been rumors and statements that persons who are HIV positive do not necessarily develop AIDS. This is certainly misleading. Not all people who are HIV positive have AIDS because the illness has not progressed to that stage. At present, the outcome of contracting HIV is ultimately AIDS and death.
HIV is primarily transmitted through infected blood and blood products and through reproductive fluids. Although the virus has been found in tears, sweat, and saliva, no cases of transmission through those fluids has been documented. The case can be made for inadequate amount of microorganisms in those fluids.
infection cycle
INFECTION PREVENTION AND CONTROL
Removing any one of the six factors described earlier will stop the infection cycle (see Fig. 9-1). This discussion concentrates on techniques used by the health care worker to stop transmission from the reservoir to the susceptible host because this is the predominant factor they can control. However, it is important to note that the imaging technologist who works when his or her resistance is low as a result of fatigue, stress, a low-grade infection, or trauma increases personal susceptibility as a host.
medical asepsis
A great deal of infection control and prevention is common sense. Consider the following analogies from daily life. If you don’t want to get paint splatter on your furniture, you cover it. If you don’t want to get dirt on your hands when you garden, wear gloves. If you don’t want to breathe drywall dust, wear a mask. If you can’t clean all the little crevices in the broiler pan, cover it with aluminum foil before you use it. These common practices are all barriers.
Barrier techniques are the front line of medical asepsis. You cannot get your hands truly clean by washing, even if you use a hand brush; wear gloves. You do not want blood to splatter on you, so you wear a gown, mask, gloves, and protective eyewear. Additionally, masks and eyewear can keep droplet and airborne pathogens away from the mucous membrane of your nose, mouth, and eyes. Using gloves also reduces the potential for spread of nosocomial infections from direct contact with antibiotic-resistant staphylococci. The authors make these statements with the understanding that “using” means using properly
microorganisms
MICROBIOLOGY OF INFECTIONS
Some basic microbiologic terms must be defined to avoid confusion in discussing infection prevention and control. Organisms that are too small to be seen without the aid of a microscope are called microorganisms. For the purposes of this discussion, microorganisms are categorized as bacteria, viruses, protozoa, and fungi. Within each of these “categories” are many different types and mutations. There are also some microorganisms that are more like “kissing cousins” to bacteria: rickettsiae, chlamydiae, and mycoplasmas.
nosocomial
Susceptible Host
In addition, these patients may be exposed to particularly virulent strains of microorganisms. Staphylococcus aureus is an example of a relatively benign microbe evolving into a deadly threat. One of the most life-threatening infections is a hospital-acquired staphylococcal (“staph”) infection. These organisms have been so exposed to antimicrobial agents that they have mutated into strains that are resistant to chemical agents. One can sterilize equipment that is contaminated, but one cannot sterilize a patient’s arm. These hospital-acquired infections are called nosocomial. They also pose a threat to health care workers. Thousands of health care workers are infected with the hepatitis B virus (HBV) each year; as many as 2% of those infected die.
pathogen
Microorganisms are present throughout the life cycle. Those capable of causing disease are called pathogens (Table 9-1). Some microorganisms live within the human body. Bacteria are found on the skin (staphylococci). Enormous numbers of bacteria are found in the feces. Many live in the saliva and mucus, some of which are capable of causing severe illness. The presence of pathogens is only one of the necessary components for disease or infection; the other factors are discussed in the following section. Removing any one of these components will break the chain of infection. This knowledge is the basis for infection prevention and control procedures: finding a way to break the chain
protozoa
Protozoa are unicellular and colonial organisms that exhibit characteristics typical of animal life. All classes of protozoa are thought to contain some species that cause disease in humans. These diseases can be transmitted through contact with contaminated feces, either directly or by mechanical transmission (e.g., from flies). They can also be transmitted through insect bites, such as malaria from mosquitoes, or directly from person to person, as with trichomoniasis, a protozoan sexually transmitted disease (STD). Protozoa are classified according to their motility (amoeba-like, flagellate, ciliar, or nonmotile). Some protozoa are able to form their own environment (cysts), which is resistant to chemical and physical changes. This allows them to survive outside the host organism.
reservoir
FUNDAMENTALS OF INFECTION
The presence of microorganisms alone does not necessarily mean an infection will ensue. The process is interdependent on the following factors:
Reservoir
Microorganisms must live and grow somewhere. Hosts who have developed infections or disease from these microbes and manifest clinical symptoms are those seen as patients. Common sense leads the health care worker to be careful around people who look or act sick or diseased. It is easy to practice wise infection control measures when potential harm is perceived. However, some pathogens live in the bodies of seemingly healthy individuals without causing readily apparent symptoms. These people may develop the disease after an appropriate incubation period, or they may be immune and may never develop the disease at all. These persons are most likely to pose a problem to health care workers. The classic example is the person who has been infected with HIV and has no symptoms. An individual may even have a negative blood test if the incubation period has not been sufficiently long to develop the marker for the test. Interestingly, the actual microbial count in the blood is often higher during the incubation period than at any other time. In short, patients are the most infectious during the time that they are asymptomatic. Carelessness usually occurs with a “healthy” patient, who may not be as healthy as he or she appears. Reservoirs may also be something other than a person. Contaminated food and water, human and animal waste, and insect toxins and wastes have all been identified and linked to major epidemics. This link in the chain of infection is what motivates health care facilities to ensure optimal “housekeeping” procedures.
universal precautions
Universal Precautions
In 1983 the CDC published “Guidelines for Isolation Precautions in Hospitals,” which directly addressed the issue of body fluid and bloodborne pathogens. In 1987 the CDC revised the recommendations by publishing “Recommendations for Prevention of HIV Transmission in Health-Care Settings.” This document changed the recommendations to state that blood and body fluid precautions should be consistently used for all patients regardless of their bloodborne infection status; that is, precautions should be universal. The recommendations were to protect the health care worker from the transmission of HIV, HBV, and other bloodborne pathogens. It should be stressed that the term “universal” refers to universal treatment of blood and certain body fluids, requiring them to be treated the same, regardless of the patient’s apparent infectious state. It does not refer to “universal protection” from transmission of all diseases. Droplet, airborne, and contact transmission of infections such as influenza, TB, and methicillin-resistant Staphylococcus aureus may or may not be addressed with “universal precautions.”
This CDC document was again revised in a 1988 publication that clarified such issues as which body fluids should be treated as potentially infectious, HBV immunization of health care workers, special settings, use of protective barriers, specific guidelines for “sharps,” and waste management. Universal procedures apply to blood or any other body fluids that contain visible blood, as well as to semen and vaginal secretions. These procedures also apply to tissues and the following fluids: cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic. However, these procedures do not apply to feces, nasal secretions, sputum, tears, sweat, urine, or vomitus. Remember, however, that universal precautions were created to deal with HIV and HBV only, so this in no way indicates that these fluids are not contaminated with other pathogens.
The rest of this chapter focuses on general procedures and how to adapt them to your setting. These recommendations are factual and clearly written but will work only if put to actual use. The key to effective protection is a consistent approach to all contact with all body substances of all patients at all times (Box 9-1).
