II . CDC Isolation Recommendations
A. Background
The 1996 CDC guidelines supercede all previous recommendations for isolation precautions in hospitals. They were revised to be as simple and user friendly as possible and to use new terms to avoid confusing them with older systems. In addition, the guidelines are based on the latest epidemiologic information on transmission of infection in hospitals. NOTE: Since each hospital is unique, they have the option to modify the CDC guidelines to meet the needs of their institution. HCW’s will note some of these differences as they change places of employment.
B. Precautions categories
1. Tier I- Standard Precautions
In the care of all patients in hospitals, regardless of diagnosis or presumed infection status, Standard Precautions is the primary strategy. These precautions always come first and are the most important precaution the HCW can implement. (for more detail refer to part I of this course).
2. Tier II- Transmission Based Precautions
These precautions are designed for patients who are diagnosed or suspected to be infected with highly transmissible pathogens. In these situations additional precautions (beyond Standard Precautions) are needed to interrupt transmission in hospitals.
In order for transmission of infections to occur, these elements must be present: a Source, a Host, and a Route of Transmission.
a. Source -
Sources include patients and HCWs with either acute disease, persons in a chronic carrier state, or persons colonized (without any apparent disease). Also, the source could be inanimate environmental objects such as medical equipment, medications or furniture.
b. Host -
A host is a person who becomes infected. Persons most susceptible to infections include the elderly, infants, persons with other underlying diseases (diabetes, HIV) , certain treatments with antibiotics , corticosteroids or other immunosuppressive agents, irradiation, surgical operations, anesthesia, and invasive devices such as IV’s, central lines, chest tubes, and urinary catheters.
c. Route of transmission -
This describes the manner in which a microorganism is transmitted from a source to a susceptible host. The goal is to interrupt the route of transmission by implementing the appropriate isolation precautions as described in the Isolation Guidelines. The CDC provides an extensive list of selected infections and conditions and the recommended type of precautions to prevent transmission. This list should be available to HCW’s in order to select or confirm the category needed for specific infections. Most hospitals provide such a list in their Infection Control Manual.
3. Isolation Categories
a. Contact Precautions
Contact precautions are designed to prevent or reduce transmission of microorganisms by direct or indirect contact.
1.) Direct is described as skin to skin contact and includes such patient care activities as bathing and turning patients (eg. by hand contact)
2.) Indirect includes contact with inanimate objets in the patient’s environment such as IV pumps, electronic thermometers, bedrails, telephones, and light switches used by the patient or by a caregiver after direct contact with the patient. The Contact mode of transmission encompasses a long list of diseases and should be one that HCW’s become familiar with for frequent use. In addition to Standard Precautions, patients should be placed in a private room or cohorted with another patient who has the same infection. Gloves should be worn when entering the room. Remove the gloves before leaving the room and immediately wash hands. NOTE: do not touch the patient or any equipment or surface as you exit the room. Wear a gown when entering the room if you anticipate your clothing will have contact with patient surfaces or items within the room. (Some hospitals require a gown for any entry to the room, so check your employers’ policies). Avoid sharing equipment between patients but if unavoidable, clean and disinfect before use on another patient. Limit patient movement from the isolation room to essential purposes only. Ensure that isolation precautions are maintained during transport and be certain to inform the receiving department of the isolation status.
b. Airborne Precautions
These precautions are designed to prevent or reduce the transmission of microorganisms that are airborne in very small droplet particles or in dust particles. The microorganisms can be scattered widely by air currents and may be inhaled by a susceptible host either in the same room or over a long distance such as through a ventilation system. The list of diseases in this category is small. The most important ones include pulmonary tuberculosis and the viruses that cause rubeola and varicella (Chicken Pox).
In addition to Standard Precautions, place the patient into a private room with monitored negative air pressure. Keep doors and windows closed. All persons entering the room must wear approved and properly fitted respiratory protection. Limit patient movement from the room for essential purposes only. When necessary, place a surgical mask or an N95 respirator mask on the patient.
The HCW needs to be properly educated about the requirements for this category. Federal OSHA has required that healthcare facilities provide a written TB plan. Information regarding TB and OSHA will be found in part III of this course.
c. Droplet Precautions
Droplet precautions are designed to prevent or reduce the transmission of large droplets containing microorganisms generated from an infected source during coughing, sneezing, talking, and during certain procedures such as suctioning, and bronchoscopy. Transmission occurs when infected droplets travel a short distance and are deposited on a hosts’ mucosa of eyes, nose or mouth. The large droplets do not remain suspended in the air. No special air handling and ventilation is required. Transmission requires close contact between source and host persons as droplets generally travel 3 feet or less through the air.
Among the more common diseases requiring Droplet Precautions are Meningococcal Meningitis, Rubella, Mumps, and some types of Influenza.
In addition to Standard Precautions, Droplet Precautions require a private room. HCW’s must wear gloves and a surgical mask when working within 3 feet of the patient. Patient transport should be limited to essential purposes only and when necessary, place a surgical mask on the patient prior to transport.
d. Combination of Isolation Precautions
More than one type of Isolation Precautions may be required for diseases that have two routes of transmission. The most frequently seen use of combinations occur with Varicella (Chicken Pox) and Disseminated Herpes Zoster (or localized HZ in immunocompromised patients). For both of these situations use Contact and Airborne precautions.
4. Multi Drug Resistant Organisms
In some states and regions resistant bacteria may be judged by the Infection Control Committee to be of special clinical or epidemiological significance. As a result, special policies may be in place to identify persons with a history of infection or colonization for routine placement in Precautions. Examples of Multi-drug resistant organisms are:
MRSA- Methicillan Resistant Staphylococcus Aureus
VRE - Vancomycin Resistant Enterococcus
These two conditions require Contact Precautions. A special emphasis should be made to HCWs regarding the transmission of microorganisms by both direct and indirect contact. Patients colonized with MRSA or VRE should be placed into Contact Precautions to prevent nosocomial spread to vulnerable patients.
5. Empiric, temporary precautions
Often the risk of transmission of infection may be highest before a definitive diagnosis can be made and before precautions can be put into place. Certain High Risk conditions may warrant placing patients in precautions prior to obtaining a definitive diagnosis. Examples include:
Escherichia Coli 0157:H7 - E.Coli
Neisseria Meningitidis - Meningitis
Mycobacterium tuberculosis - TB
Pertussis - Whooping Cough
Respiratory infections - RSV
Multi Drug Resistant - MRSA and VRE
Some hospitals may have policies in place for Empiric precautions.
