Isolation or transmission-based precautions


Isolation or transmission-based precautions

All of the measures discussed this far (universal precautions, standard precautions and decontamination) are essential practices within healthcare settings. There are times, however, when the risk of nosocomial infections is greatly increased, due to the type of infection found. Under such a scenario, it is important to understand the second tier of CDC’s recommendations.

Since the mid 1990s the CDC have recommended the use of isolation or transmission-based precautions as the second tier in preventing nosocomial infections.

CDC’s guidance on isolation techniques was updated at that time, based upon the latest epidemiological data on the transmission of infections within acute care settings. Isolation precautions are now based on the means of transmission rather than the disease. In addition, this updated information highlighted the fact that many patients who have been infected or colonized with certain organisms could be cared for under universal or standard precautions alone (see Appendix 1).

While the recommendations may need to be adapted for specific settings, the principles relating to prevention of organism transmission still apply


Isolation or transmission-based precautions are intended to prevent organisms from cross infecting via the routes of transmission discussed earlier in the cycle of infection. (Bloodborne transmission has already been discussed under universal precautions).


precautions Since organisms transmissible through the air can be widely dispersed, specific air ventilation is required to manage their dispersion. Techniques include the use of monitored negative airflow ventilation with at least six air changes per hour and filtration of direct exhaust to the outside. If such a system is not available, there is an increased risk that susceptible patients, even some distance away, may inhale the organisms. Surgical masks that cover the mouth and nose should be worn by staff caring for such patients, and by the patient themselves, should they need to leave their designated area. The use of respiratory protection devices is extremely important for patients who have infectious pulmonary tuberculosis (see Module 5).

CDC-recommended devices include the N95 respirator/surgical mask made by 3M. Additionally, there is the 3M 6000 series, which is reusable. These devices ensure that these airborne particles are not inhaled. Other masks do not provide this specific protection. Although it may be difficult to obtain these specialized devices, they are imperative for healthcare workers’ and patients’ protection. The cost and inconvenience of treating cases of cross infection is much higher

Droplet precautions

Organisms transmitted by droplet require close contact. Measures to limit cross infection include placing the patient in a single room or having at least three feet between patients; wearing of surgical masks by staff coming within three feet of the patient, and the wearing of a mask by the patient, when they leave their designated area

Contact precautions

Certain pathogenic organisms such as MRSA, Clostridium difficile, and Vancomycin-resistant enterococci can be transmitted directly through contact with infected or colonized patients, or indirectly through contact with potentially contaminated items or surfaces. Isolation of the patient is essential and can limit the transmission of organisms. In addition protective clothing, including gloves and aprons, should be worn by health staff

Common vehicle transmission

Common vehicle transmission can be prevented by utilizing aseptic, sterile or clean techniques whenever fluids or medications are being made up or given to patients, and by utilizing good principles of food hygiene

Vectorborne transmission

can be avoided by keeping healthcare facilities free of arthropods and insects. The CDC recommendations for isolation precautions concentrate on contact, airborne transmission, and droplet transmission as the most significant risks within healthcare facilities. Examples of organisms, their routes of transmission, and management strategies can be found in Appendix 1