These guidelines are recommendations from the Center for Disease Control and Prevention. They are not intended to be used as rules from regulatory agencies. It is up to the facility to determine if these guidelines are appropriate for their setting.

1. Rationale

Transmission of infection within any health care facility requires three elements: a source of infecting organisms; a susceptible host, and a means of transmission for the organism.

2. Source

Human sources of infecting microorganisms in health care may be patients, personnel, and on occasion visitors. Some of these individuals maybe carrying epidemiological strains of bacteria (i.e., MRSA) and thereby are considered colonized and not infected. However, these strains may be spread to other patients/residents if good hygiene (i.e., handwashing) is not performed. The patient/resident’s own indigenous flora may be a source for infection (i.e., Escherichia coli causing UTI’s). Sometimes environmental objects may be a source, however this often occurs rarely in healthcare settings.

3. Host

Resistance to both disease (pathogenic) and opportunistic microorganisms varies greatly. Some persons may demonstrate resistance to colonization of an infectious organism; others exposed to the same agent may establish a commensal (a parasitic organism that causes no harm to the host) relationship with the infecting organism and demonstrate no symptoms (carrier) or indications of a disease state. However, others may develop clinical signs of infections. There are a variety of host factors that may contribute to a disease state. For example, age, underlying disease, treatment with antimicrobials, corticosteriods or other immunosuppressive drugs; irradiation, and breaks in skin can contribute to the susceptibility of a host to infection. Patients/residents have

to be flagged according to their susceptibility to disease in their charts.

4. Transmission

Microorganisms are transmitted in healthcare by several routes and the same organism may be transmitted by more than one route. There are five main routes of transmission: contact, droplet, airborne, common vehicle, and vector-borne. Common vehicle and vector-borne transmission occurs very seldom in health care facilities in the United States and thus plays an insignificant role in nosocomial (healthcare acquired) infections.

1. Contact transmission

The most important and frequent mode of transmission of nosocomial infections is contact transmission. Contact transmission is divided into two subgroups:

1. direct contact - involves a direct body surface-to-body surface contact and physical transfer of microorganisms between a susceptible host and an infected or colonized person, such as occurs when a person turns a patient/resident, gives a patient/resident a bath, or some other direct patient/resident activity that requires personal contact. Direct contact transmission can also occur between two patient/residents where one serves as a host the other the source of the infecting organism. This is often seen in long-term care settings.

2. indirect-contact - involves contact of a susceptible host with a contaminated intermediate object, usually inanimate (not human or animal), such as contaminated instruments, needles, or dressings, or contaminated gloves that are not changed between patients/residents.

2. Droplet transmission

This is considered a form of contact transmission. However, the mechanism of transfer of the pathogen to the host is quite distinct from either direct-or indirect- contact transmission. Droplets are generated from the source person primarily during coughing, sneezing, and talking and during the performance of certain procedures such as suctioning and bronchoscopy. Transmission occurs when droplets containing microorganisms generated from infected persons are propelled a short distance (within a 3 feet range) through the air and deposited on the host’s conjunctivae (membrane lining the eyelids and covering the eyeball), nasal mucosa, or mouth.. Because droplets do not remain suspended in the air, special air handling and ventilation are not required to prevent droplet transmission.

3. Airborne transmission

Airborne transmission occurs by dissemination of either airborne droplet nuclei (small particle residue which are 5 micrometers or smaller in diameter) of evaporated droplets containing microorganisms that remain suspended in the air for long periods of time. Microorganisms carried in this manner can be widely dispersed by air currents and may become inhaled by a susceptible host within the same room or over a longer distance from the source patient/resident.. To prevent this from occurring special air handling and ventilation are required to prevent airborne transmission. Microorganisms transmitted by airborne transmission include Mycobacterium tuberculosis, rubeola and varicella viruses.

4. Common vehicle transmission

This manner of transmission applies to microorganisms transmitted by contaminated by food, water, medications, devices and equipment. The infection control practitioner must be able to obtain sufficient data to prove that these items are responsible for an outbreak.

Please check with the microbiologist in your laboratory to discuss the type of specimens that must be submitted for cultures.

5. Vector-borne transmission

This form of transmission occurs when vectors such as mosquitoes, flies, rats and other vermin transmit microorganisms. This type of transmission route is rare in the United States.

Remember that isolation precautions are designed to prevent transmission of microorganisms by these routes in all health care areas. Nursing homes generally are incapable of maintaining a resident with tuberculosis. However, both the medical and nursing staff should be able to recognize symptoms for tuberculosis so that a transfer to a hospital is done as rapidly as possible.

Placing a patient/resident in isolation precautions often create many disadvantages such as use of specialized equipment, environmental modifications, increase in personnel activity, private rooms (decreases valuable space that might otherwise accommodate more than one patient/resident), and etc. All of these disadvantages plus the added anxiety of the patient/resident and visitors not to mention increased in health care cost. So if a patient/resident is going to be placed in isolation one has

to think about all these factors. However, the placement of a patient/resident in isolation must be weighed against the healthcare’s mission to prevent the spread of serious and epidemiological important microorganisms.

5. Fundamentals of isolation precautions

A variety of infection control measures are used for decreasing the risk of transmission of microorganisms in a healthcare setting. For example:

1. Handwashing and gloving

Handwashing is the single most important measure to reduce the risks of transmitting microorganisms from one person to another or from one site to another on the same patient (i.e., perianal region to the G-tube).Washing hands as promptly and thoroughly as possible between patient contacts and after contact with blood, body fluids, secretions, excretions, and equipment or articles contaminated by them is an important component of infection control and isolation precautions.

1. Gloves

Gloves are worn for three important reasons:

1. Gloves are worn to provide a protective barrier and prevent gross contamination of the hands when touching blood, body fluids, secretions, excretions, mucous membranes, and nonintact skin (OSHA’s bloodborne pathogen rule, 1991).
2. Gloves are worn to reduce the likelihood that microorganisms present on the hands of personnel will be transmitted to patients during invasive or other patient care procedures that involve touching a patient’s mucous membrane.
3. Gloves are worn to reduce the likelihood that hands of personnel contaminated with microorganisms from a patient or fomite can transmit these microorganisms to another patient. Gloves must be changed between patients and hands washed after gloves are removed.

Wearing of gloves does not replace the need for hand washing for the following reasons:

1. Gloves may have small inapparent defects or be torn during use.
2. Hands can become contaminated during removal of gloves.

FAILURE TO CHANGE GLOVES BETWEEN PATIENT/RESIDENT CONTACTS IS AN INFECTION CONTROL HAZARD.

2. Patient placement

Appropriate patient placement is a significant component of isolation precautions. A private room is important to prevent direct or indirect contact transmission when the source patient has poor hygienic habits, contaminates the environment or cannot be expected to assist in maintaining infection control precautions (i.e., infants, children, and patients with altered mental status). When possible, a patient with highly transmissible or epidemiological important microorganisms (i.e., MRSA, VRE or aminoglycoside resistant gram negative organism) is placed in a private room with hand washing and toilet facilities to reduce opportunities for transmission of microorganisms.

Patients infected with the same organism can usually share a room provided:

1. they are not infected with other potentially transmissible organisms;
2. the likelihood of reinfection with the same organism is minimal.

Such sharing of rooms, also referred to as cohorting patients, is especially useful during outbreaks or when there is a shortage of private rooms. When a private room is not available and cohorting is not achievable, it is important to consider the epidemiologic pattern and mode of transmission of the infecting organism and the population being served in determining patient placement. When an infected patient shares a room with a noninfected patient, it is important that patients, personnel, and visitors take precautions to prevent the spread of infection and that roommates are carefully selected.

A private room with appropriate air handling and ventilation is particularly important for reducing the risks of transmission of microorganisms from a source patient to susceptible patients and other persons in healthcare when the microorganism is spread by airborne transmission. Long-term care facilities, unless associated with an acute care hospital can not practice airborne isolation because of the lack of adequate ventilation. However, the importance of recognizing symptoms (i.e., tuberculosis), and placing the resident in a private before transferring to an acute care setting reduces the chances of over exposure with these types of organisms. Please see CDC recommendations concerning tuberculosis control.

3. Transporting infected patients

Limiting the movement and transport of patients infected with virulent or epidemiologically important microorganisms and ensuring that such patients/residents leave their rooms only for essential purposes reduces the opportunities for transmission of microorganisms in any healthcare environment. When transportation is necessary it is important to follow three recommendations:

1. appropriate barriers (masks, barrier-proof dressings) are worn or used by the patient to reduce the opportunity for transmission of pertinent microorganisms to other patients, personnel, and visitors and to reduce the contamination of the environment;
2. personnel in the area to which the patient/resident is to be taken are notified of the impending arrival of the patient and of the precautions to be used to reduce the risk of transmission of infectious microorganisms.
3. patients are informed ways by which they can assist in preventing the transmission of their infectious microorganisms to others.

4. Masks, respiratory protection, face shields

Various types of masks, goggles, and face shields are worn alone or in combination to provide barrier protection.

A mask that covers both the nose and

mouth and goggles or a face shield are

worn by personnel in health care during procedures and patient-care activities that are likely to generate splashes or sprays of blood, body fluids, secretions, or excretions to provide protection of the mucous membranes of the eyes, nose, and mouth from contact transmission of pathogens. The wearing of masks, eye protection, and face shields in specified circumstances to reduce the risk of exposures to blood-borne pathogens is mandated by the OSHA blood-borne pathogens final rule. A surgical mask is generally worn by healthcare personnel to provide protection against spread of infectious large-particle droplets that are transmitted by close contact and generally travel only short distances (up to 3 feet) from infected patients who are coughing or sneezing.

An area of major concern and controversy over the last several years has been the role and selection of respiratory protection equipment and the implications of a respiratory protection program of tuberculosis in healthcare. Traditionally, although the efficacy was not proven, a surgical mask was worn for isolation precautions when patients/residents were known or

suspected to be infected with pathogens spread by the airborne route of transmission. In 1990, CDC proposed that surgical masks may not be effective in preventing the inhalation of droplet nuclei (1 - 5 micrometers in diameter) and recommended the use of particulate respirators despite the fact that the efficacy of particulate respirators in protecting persons from inhalation of Mycobacterium tuberculosis had not been demonstrated. A great deal of controversy followed. In July 1995, NIOSH finally provided a broader range of certified respirators that meet the performance criteria for protection. NIOSH has indicated that the N95 (N category at 95% efficiency) meets the CDC performance criteria for tuberculosis respirators.

5. Gowns and protective apparel

Various types of gowns and protective apparel are worn to provide barrier protection and reduce opportunities for transmission of microorganisms in health care environments. Gowns are worn to prevent contamination of clothing

and protect the skin of personnel from blood and body fluid exposure. Gowns that will prevent soak-through are to be used. Patient gowns are not acceptable. Gowns are also worn by personnel during the care of patients infected with epidemiologically important organisms to reduce the opportunity for transmission of pathogens from patients/residents or items in their environment to other patient/residents environments. Health care personnel should know the limitations of the gowns that they are using, where are they found and how to remove them if grossly contaminated, and final disposition of such gowns.

6. Patient-care equipment and articles

Many factors determine whether special handling and disposal of used patient-care equipment and articles are prudent or required, including the likelihood of contamination with infective material. For example:

1. the ability to cut, stick or otherwise cause injury;
2. severity of disease;
3. environmental stability of the pathogens.

Some used articles are enclosed in containers or bags to prevent

to prevent inadvertent exposure to patients, personnel, visitors and to prevent contamination of the environment.

Used sharps are placed in puncture resistant containers.

Other articles are placed in a bag. One bag is adequate if the bag is sturdy and the article can be placed in the bag without contaminating the outside of the bag.

Contaminated, reusable critical medical devices or patient-care equipment (i.e., equipment that enters normally sterile tissue or through which blood flows) or semicritical medical devices or patient-care equipment (i.e., equipment that touches mucous membranes) are sterilized or disinfected (reprocessed) after use to reduce the risk of transmission of microorganisms to other patients. The type of reprocessing is determined by the article and its intended use.

Non-critical equipment (i.e., equipment that touches intact skin) contaminated with blood, body fluids, secretions, or excretions is cleaned with an EPA registered disinfectant that has tuberculocidal activity. Disposable equipment is handled and transported in a manner that will not cause injury or environmental contamination.

7. Linen and laundry

Although soiled linen may be contaminated with a high concentration of both pathogenic and opportunistic organisms, the risk of disease transmission is negligible if it is handled, transported and laundered in a manner that avoids transfer of microorganisms to patients, personnel and the environment.

Rather than rigid rules and regulations, hygienic and common sense storage and processing of clean and soiled linen are recommended. Guidelines for handling and processing linens have been published by the Joint Commission on Health Care Laundry Guidelines. There is absolutely no need to wash linens from isolated areas separately. The processing of linens (i.e., detergents, sours, rinsing, drying) produces a biologically safe product.

8. Dishes, glasses and cups, and eating utensils

Disposable dishes are not needed for persons in isolation because the processing destroys all disease producing organisms. The combination of hot water and detergents used in healthcare dishwashers in sufficient to decontaminate glasses, cups and eating utensils. It is important that all food processing equipment is broken down and washed and allowed to air-dry before reassembling.

9. Routine and terminal cleaning

The room or cubicle and bedside equipment of patients on Transmission- based Precautions are cleaned with the same procedures used for all patient/residents on Standard Precautions unless the infecting organism requires special decontamination (bloodborne pathogens) procedures (tuberculocidal EPA registered disinfectant). It is important that housekeepers use common sense procedures in cleaning. Procedure manual should be written and updated on a yearly basis (or as often needed by regulatory agencies). Supervisors must be involved in in-servicing of all personnel to make certain that proper handling and use of disinfectants are being employed. Contamination of the environment by any body fluid from patients/residents must be cleaned up as soon as possible. Organisms such as Enterococcus faecalis (some strains are now showing resistance to vancomycin) can actually survive for prolonged periods of time in the environment. Staphylococcus aureus has demonstrated survival on glass cover slips under laboratory conditions for as long as 2 weeks. The methods, thoroughness, and frequency of cleaning and the products used are determined by the healthcare facility.

6. Isolation Precautions

There are two tiers of isolation precautions.

1. Standard precautions which is designed to care for all patients in healthcare regardless of their diagnosis or presumed infection status.
2. Transmission-based precautions are for patients known or suspected to be infected by epidemiologically important pathogens spread by airborne or droplet transmission or by contact with dry skin or contaminated surfaces.

 

Standard Precautions apply to:

1. blood
2. all body fluids, secretions, and excretions except sweat, regardless whether they contain visible blood
3. nonintact skin
4. mucous membranes

Standard Precautions are designed to reduce the risk of transmission of microorganisms from both recognized and unrecognized sources of infection in healthcare.

Transmission-based Precautions

They may be combined together for diseases that have multiple routes of transmission (See Appendix A). When used either singularly or in combination, they are to be used in addition to Standard Precautions.

Airborne Precautions

NOTE: Surgical masks can not be used by healthcare workers to protect themselves against tuberculosis suspected or diagnosed patients.

Airborne transmission occurs by dissemination of either airborne droplet nuclei (small particle residue with a diameter of 5 micrometers or less) of evaporated droplets that may remain suspended in the air for long periods of time or dust particles containing infectious agents. Microorganisms carried in this manner can be widely spread by air currents and may become inhaled or deposited on a susceptible host within the same room or over a longer distance from the source patient. Special air handling and ventilation are required to prevent airborne transmission. Airborne Precautions apply to patients/residents know or suspected to be infected with epidemiologically important pathogens that can be transmitted by the airborne route. Since long-term care facility do not have the capacity to perform Airborne Precautions, it is important that the nursing and medical staff recognize symptoms or the probability of a disease (i.e., tuberculosis) which may require such precautionary measures so transportation to an acute care setting is done as soon as possible to prevent personnel, resident, and visitor exposure. The types of diseases or conditions that require Airborne Precautions can be seen in Appendix A.

Droplet Precautions

Droplet transmission involves contact of the conjunctivae, or the mucous membranes of the nose or mouth of a susceptible with large particle droplets (larger than 5 micrometers in diameter) containing microorganisms generated from a person who has a clinical disease or a carrier of the microorganism. Droplets are generated from the source person primarily during coughing, sneezing, or talking, and during performance of certain procedures such as suctioning and bronchoscopy. Transmission via large-particle droplets requires close contact between source and recipient persons because droplets do not remain suspended in the air and generally travel only short distances, usually 3 feet or less through the air.

Because droplets do not remain suspended in the air, special air handling and ventilation are not required to prevent droplet transmission. Droplet Precautions apply to any patient known or suspected to be infected with epidemiologically important pathogens that can be transmitted by infectious droplets. Please see Appendix A for infections or conditions that require Droplet Precautions.

Direct-contact transmission involves skin-to-skin contact and physical transfer of microorganisms to a susceptible host from an infected or colonized person, such as occurs when personnel turn a patient, gives a patient a bath, or performs other patient care activity that requires physical contact.

Direct-contact transmission can also occur between two patients (i.e., by hand contact), with one serving as the source of infectious microorganisms and the other as a susceptible host. Indirect-contact transmission involves contact of a susceptible host with a contaminated intermediate object, usually inanimate, in the patient’s environment. Contact Precautions apply to specified patients known or suspected to be infected or colonized (presence of microorganisms in or on patients/residents but without clinical signs and symptoms of infection) with epidemiologically important microorganisms that can be transmitted by direct contact or indirect contact. See Appendix A for those infections or conditions that require Contact Precautions.

These guidelines were revised by CDC for the following reasons:

1. To be epidemiologically sound;
2. To recognize the importance of all body fluids, secretions, and excretions in the transmission of nosocomial pathogens;
3. To contain adequate precautions for infections transmitted by the airborne, droplet, and contact routes of transmission;
4. To be as simple and user friendly as possible;
5. To use new terms to avoid confusion with existing infection control and isolation systems.

In order to implement these guidelines, educational forums must be developed in order to reach all levels of employees. The purpose of this document is to help staff development coordinators develop the first step in the educational process - notes.

If you have any questions concerning the organisms or this document, please call me at Consulting Services, 859-623-3973

Raymond B. Otero, Ph.D.
Consultant

Reference:

Guideline for isolation precautions in hospitals.

Hospital Infection Control Practices Advisory Committee. Center for Disease Control and Prevention. 1996.