The Guideline for Isolation Precautions in Hospitals contains many important changes from previous editions of the manual Isolation Techniques for Use in Hospitals:

1. Rather than recommending only an isolation system based on categories of isolation, we have included an alternative system: disease-specific isolation precautions. For the first time, hospitals can choose one of these alternative systems for isolation—or they can, of course, design their own system. Some hospitals may prefer to continue using the more familiar, convenient, and simple category-specific isolation precautions. Disease-specific isolation precautions, however, may be more economical, in that only the particular precautions to interrupt transmission of the specific disease are recommended, so time and materials are not spent on unnecessary precautions. With disease-specific isolation precautions, we recommend using a single instruction card on which the need for specific precautions can be shown by checking appropriate items and filling in blanks. When isolation categories are used, we still recommend using standard color-coded category-specific instruction cards; however, the colors have been changed and the cards have been revised to correspond to changes made in the category-specific recommendations.

2. Major changes have been made in the titles of and specifications for categories of isolation and the diseases or conditions requiring specific categories of isolation.

a. We have retained 3 categories of isolation (Strict Isolation, Respiratory Isolation, and Enteric Precautions) with modifications. We have substantially modified Enteric Precautions to minimize unnecessary use of gowns and gloves. This modification has permitted infections formerly under Excretion Precautions to be combined with those under Enteric Precautions. We have added and deleted diseases from Strict Isolation and Respiratory Isolation.

To use the new approaches introduced in this guideline most effectively, each hospital's infection control committee must thoroughly review the entire guideline and MAKE A DECISION regarding which of the alternative systems of isolation precautions to use.

The first step is for all members of the committee who will participate in this decision to review the entire guideline carefully. This is necessary because the Guideline for Isolation Precautions in Hospitals contains many changes in recommended procedures as well as format from the previous manual Isolation Techniques for Use in Hospitals. To facilitate this review, we have summarized the most important changes in the introduction to the guideline and have included the rationale for these changes in other sections of the document.

The second step is for the infection control committee to MAKE A DECISION as to whether their hospital will use System A, the Category-Specific System, or System B, the Disease-Specific System, both of which are thoroughly described in this guideline. Of course, in some hospitals the committee may decide instead to use the information and recommendations in this guideline to create their own system of isolation precautions. However, from a logistical point of view, the committee should not try to combine different elements taken from both systems, because mixing the 2 approaches may lead to confusion among hospital personnel who are expected to apply the isolation precautions in patient care. Personnel throughout the hospital who will be using isolation precautions should be trained to apply only the system that is officially adopted by the infection control committee.

Spread of infection within a hospital requires 3 elements: a source of infecting organisms, a susceptible host, and a means of transmission for the organism.

The source of the infecting agent may be patients, personnel, or on occasion, visitors, and may include persons with acute disease, persons in the incubation period of the disease, or persons who are colonized by the infectious agent but have no apparent disease. Another source of infection can be the person's own endogenous flora (autogenous infection). Other potential sources are inanimate objects in the environment that have become contaminated, including equipment and medications.

Patients' resistance to pathogenic microorganisms varies greatly. Some persons may be immune to or able to resist colonization by an infectious agent; others exposed to the same agent may establish a commensal relationship with the infecting organism and become asymptomatic carriers; still others may develop clinical disease. Persons with diabetes mellitus, lymphoma, leukemia, neoplasia, granulocytopenia, or uremia and those treated with certain antimicrobials, corticosteroids, irradiation, or immunosuppressive agents may be particularly prone to infection. Age, chronic debilitating disease, shock, coma, traumatic injury, or surgical procedures also make a person more susceptible.

Microorganisms are transmitted by various routes, and the same microorganism may be transmitted by more than 1 route. For example, varicella-zoster virus can spread either by the airborne route (droplet nuclei) or by direct contact. The differences in infectivity and in the mode of transmission of the various agents form the basis for the differences in isolation precautions that are recommended in this guideline.

There are 4 main routes of transmission—contact, vehicle, airborne, and vectorborne.

This section contains information essential to understanding and properly using the isolation precautions that appear in the guideline and on the instruction cards. Many of the techniques and recommendations for isolation precautions are appropriate not only for patients known or suspected to be infected but also for routine patient care. For example, gowns are appropriate for patient-care personnel when soiling with feces is likely, whether or not the patient is known or suspected to be infected with an enteric pathogen, and caution should be used when handling any used needle.

Handwashing is the single most important means of preventing the spread of infection. Personnel should always wash their hands, even when gloves are used, after taking care of an infected patient or one who is colonized with microorganisms of special clinical or epidemiologic significance, for example, multiply-resistant bacteria. In addition, personnel should wash their hands after touching excretions (feces, urine, or material soiled with them) or secretions (from wounds, skin infections, etc.) before touching any patient again. Hands should also be washed before performing invasive procedures, touching wounds, or touching patients who are particularly susceptible to infection. Hands should be washed between all patient contacts in intensive care units and newborn nurseries. (See Guideline for Hospital Environmental Control: Antiseptics, Handwashing, and Handwashing Facilities.)

When taking care of patients infected (or colonized) with virulent or epidemiologically important microorganisms, personnel should consider using antiseptics for handwashing rather than soap and water, especially in intensive care units.

Category-specific isolation precautions is 1 of 2 isolation systems recommended by CDC. This system was the only one recommended in the first 2 editions of the CDC manual, Isolation Techniques for Use in Hospitals. Isolation categories are derived by grouping diseases for which similar isolation precautions are indicated. For diseases to be grouped into isolation categories, more isolation precautions must be required with some diseases than just those that are necessary to prevent transmission of those diseases. (Hospitals wishing to avoid overuse of isolation precautions may use the alternative isolation system, disease-specific isolation precautions.) Nevertheless, category-specific isolation precautions have advantages in that they are easier to administer and to teach personnel.

Seven isolation categories are used: Strict Isolation, Contact Isolation, Respiratory Isolation, Tuberculosis (AFB) Isolation, Enteric Precautions, Drainage/Secretion Precautions, and Blood/Body Fluid Precautions. The specifications for each category and the diseases and conditions included in the category are discussed below. (Additional information essential to understanding and properly using category-specific isolation precautions is contained in the preceding section, Techniques for Isolation Precautions, and in Table A, Category-Specific Isolation Precautions.)

Strict Isolation is an isolation category designed to prevent transmission of highly contagious or virulent infections that may be spread by both air and contact.

1. Private room is indicated; door should be kept closed. In general, patients infected with the same organism may share a room.

2. Masks are indicated for all persons entering the room.

3. Gowns are indicated for all persons entering the room.

Patients requiring intensive care are usually at higher risk than other patients of becoming colonized or infected with organisms of special clinical or epidemiologic significance. Three reasons are that contacts between these patients and personnel are frequent, the patients are clustered in a confined area, and many of them are unusually susceptible to infection. Moreover, critically ill patients are more likely to have multiple invasive procedures performed on them. Because there is ample opportunity for cross-infection in the Intensive Care Unit (ICU), infection control precautions must be done scrupulously. Frequent in-service training and close supervision to ensure adequate application of infection control and isolation precautions are particularly important for ICU personnel. (See Guideline for Hospital Environmental Control: Intensive Care Units.)

Most ICUs pose special problems for applying isolation precautions, hence some modifications that will neither compromise patient care nor increase the risk of infection to other patients or personnel may be necessary. The isolation precaution that will most often have to be modified is the use of a private room. Ideally, private rooms should be available in ICUs, but some ICUs do not have them or do not use them for patients who are critically ill if frequent and easy accessibility by personnel is crucial. When a private room is not available or is not desirable because of the patient's critical condition, and if airborne transmission is not likely, an isolation area can be defined within the ICU by curtains, partitions, or an area marked off on the floor with tape. Instructional cards can be posted to inform personnel and visitors about the isolation precautions in use.

Isolation precautions for newborns and infants may have to be modified from those recommended for adults because 1) usually only a small number of private rooms are available for newborns and infants, and 2) during outbreaks, it is frequently necessary to establish cohorts of newborns and infants. Moreover, a newborn may need to be placed on isolation precautions at delivery because its mother has an infection.

It has often been recommended that infected newborns or those suspected of being infected (regardless of the pathogen and clinical manifestations) should be put in a private room. This recommendation was based on the assumptions that a geographically isolated room was necessary to protect uninfected newborns and that infected newborns would receive closer scrutiny and better care in such a room. Neither of these assumptions is completely correct.

Separate isolation rooms are seldom indicated for newborns with many kinds of infection if the following conditions are met: 1) an adequate number of nursing and medical personnel are on duty and have sufficient time for appropriate handwashing, 2) sufficient space is available for a 4- to 6-foot aisle or area between newborn stations, 3) an adequate number of sinks for handwashing are available in each nursery room or area, and 4) continuing instruction is given to personnel about the mode of transmission of infections. When these criteria are not met, a separate room with handwashing facilities may be indicated.

Patients with certain diseases (for example, leukemia, cancer, and extensive skin conditions, such as severe burns or dermatitis) and patients who are receiving certain therapeutic regimens (for example, total body irradiation, steroid or antimetabolite therapy) are highly susceptible to infection. These compromised patients are often on special “protective” patient-care regimens intended to reduce the risk of infection. One such regimen, Protective Isolation (as outlined in the previous editions of Isolation Techniques for Use in Hospitals), does not appear to reduce this risk any more than strong emphasis on appropriate handwashing during patient care.

Protective isolation, as previously outlined, may fail to reduce the risk of infection because compromised patients are often infected by their own (endogenous) microorganisms or are colonized and infected by microorganisms transmitted by the inadequately washed hands of personnel or by nonsterile items used in routine protective isolation. Such items may include patient-care equipment, food, water, and air. Some studies suggest that vigorous efforts to exclude all microorganisms by using patient-isolator units, eradicating endogenous flora, and sterilizing food, water, and fomites may prevent or delay onset of some infections; thus, these procedures have been recommended by some for use with very-high-risk patients who have a predictable temporary period of high susceptibility. However, these extraordinary and expensive precautions do not appear warranted for most compromised patients.

Burn wounds have been classified as major or minor by various investigators according to several risk factors for burn-associated complications. We have considered only the infectious complications of burns. Therefore, we have classified major burn wounds as those that cannot effectively be covered or whose drainage cannot effectively be contained by use of dressings. The drainage from a minor burn can be covered and contained by dressings.

Most major burn wounds and many minor ones have become infected by the second or third day after the burn occurs. Care of burn patients, therefore, involves efforts to prevent colonization and infection of the wound, and isolation precautions to prevent transmission to other patients. Other important methods of care include use of topical and systemic antimicrobials, vaccines, and general supportive measures.

It is beyond the scope of this guideline to present comprehensive infection control recommendations for taking care of patients with burns. We have, however, made recommendations for isolation precautions for both major and minor burns infected with various pathogens. Rather than listing burn wounds separately, we have grouped them under the subheading “skin, wound, or burn infection.”

In the United States, about 5 million persons work in more than 7,000 hospitals. These personnel may become infected through exposure to infected patients if proper precautions are not used, or acquire infection outside the hospital. They may then transmit the infection to susceptible patients or other hospital personnel, members of their households, or other community contacts. In this guideline, we focus on diseases that are of particular concern to hospital personnel because of the possibility of transmission. In some instances we focus our discussion on transmission of infectious disease from patient-care personnel to patients. In other instances we focus on transmission of disease from patients to patient-care personnel. Recommendations for prevention and control are limited to these areas. We frequently refer to the Guideline for Isolation Precautions in Hospitals, where suggestions can be found on precautions that personnel may use when taking care of patients to prevent the spread of infection to themselves, other personnel or patients, and visitors.

Personnel who have direct contact with patients include nursing personnel, medical house staff, clinical faculty, attending physicians, paramedical staff, and nursing and medical students. Since other hospital personnel may have exposure to patients that is comparable in quality, intensity, and duration to that of patient-care personnel, hospitals may also consider them in applying these recommendations. Risk to patients from personnel with whom patients have only brief casual contact, or risk to these personnel, is generally felt to be low.