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Infection Control in Health-Care Settings
TB can be transmitted in just about any setting. It can be spread in places such as homes or worksites. However, TB is most likely to be transmitted in health care settings when health care workers and patients come in contact with persons who have unsuspected TB disease, who are not receiving adequate treatment, and who have not been isolated from others. All health-care settings need an infection-control program designed to ensure the following:
- Prompt detection of TB disease;
- Airborne precautions; and
- Treatment of people who have suspected or confirmed tuberculosis (TB) disease.
Overview of TB Infection-Control Measures
The TB infection-control program should be based on the following three-level hierarchy of control measures:
- Administrative controls
- Environmental controls
- Use of respiratory protective equipment
The first and most important level of the hierarchy, administrative controls, are management measures that are intended to reduce the risk or exposure to persons with infectious TB. These control measures consist of the following activities:
- Assigning someone the responsibility for TB infection control in the health care setting;
- Conducting a TB risk assessment of the setting;
- Developing and implementing a written TB infection-control plan;
- Ensuring the availability of recommended laboratory processing, testing, and reporting of results;
- Implementing effective work practices for managing patients who may have TB disease;
- Ensuring proper cleaning, sterilization, or disinfection of equipment that might be contaminated (e.g., endoscopes);
- Educating, training, and counseling health care workers, patients, and visitors about TB infection and disease;
- Testing and evaluating workers who are at risk for exposure to TB disease;
- Applying epidemiology-based prevention principles, including the use of setting-related TB infection-control data;
- Using posters and signs to remind patients and staff of proper cough etiquette (covering mouth when coughing) and respiratory hygiene; and
- Coordinating efforts between local or state health departments and high-risk health-care and congregate settings.
The second level of the hierarchy is the use of environmental controls to prevent the spread and reduce the concentration of infectious droplet nuclei. This includes two types of environmental control.
- Primary environmental controls consist of controlling the source of infection by using local exhaust ventilation (e.g., hoods, tents, or booths) and diluting and removing contaminated air by using general ventilation.
- Secondary environmental controls consist of controlling the airflow to prevent contamination of air in areas adjacent to the source airborne infection isolation (AII) rooms; and cleaning the air by using high efficiency particulate air (HEPA) filtration, or ultraviolet germicidal irradiation.
The third level of the hierarchy is the use of respiratory-protection control. It consists of the use of personal protective equipment in situations that pose a high risk of exposure to TB disease.
Use of respiratory protection equipment can further reduce risk for exposure of health care workers to infectious droplet nuclei that have been expelled into the air from a patient with infectious TB disease. The following measures can be taken to reduce the risk for exposure:
- Implementing a respiratory protection program;
- Training health care workers on respiratory protection; and
- Educating patients on respiratory hygiene and the importance of cough etiquette procedures.
Determining the Infectiousness of TB Patients
The infectiousness of a TB patient is directly related to the number of droplet nuclei carrying M. tuberculosis (tubercle bacilli) that are expelled into the air. The number of tubercle bacilli expelled by a TB patient depends on the following factors:
- Presence of a cough
- Cavity in the lung
- Acid-fast bacilli on sputum smear
- TB disease of the lungs, airway, or larynx
- Patient not covering mouth and nose when coughing
- Not receiving adequate treatment or having prolonged illness
- Undergoing cough-inducing procedures
- Positive sputum cultures
Patients can be considered noninfectious when they meet all of the following three criteria:
- They have three consecutive negative AFB sputum smears collected in 8- to 24-hour intervals (one should be an early morning specimen);
- They are compliant with an adequate treatment regimen for two weeks or longer; and
- Their symptoms have improved clinically (for example, they are coughing less and they no longer have a fever).
CDC recommendations on infection control provide evidence-based guidance. For regulations in your area, refer to state and local regulations and contact your local Occupational Safety and Health Administration (OSHA) officeexternal icon (https://www.osha.gov/html/RAmap.html).
CDC. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005pdf icon. MMWR 2005; 54(No. RR-17).
Respiratory Protection in Health-Care Settings – Fact Sheet