TB Infection Control
After going through this module we will understand
1) Administrative controls – the first level in the hierarchy of TB infection-control measures; managerial measures that reduce the risk for exposure to persons who have or are suspected to have TB disease.
Airborne infection isolation (AII) room – formerly called “negative pressure isolation room.” A room with special characteristics to prevent the spread of droplet nuclei expelled by a TB patient, including negative-pressure ventilation.
Close contact – a person who has shared the same air space in a household or other enclosed environment for a prolonged period of time (days or weeks, not minutes or hours) with a person with suspected or confirmed TB disease.
cough-inducing procedures – procedures that make a patient cough, such as sputum induction and bronchoscopy.
2) Environmental controls – the second level in the hierarchy of TB infection-control measures; engineering systems used to prevent the transmission of TB in health care settings, including ventilation, high-efficiency particulate air (HEPA) filtration, and ultraviolet germicidal irradiation.
health care setting – a place where health care is delivered; includes inpatient, outpatient settings, TB clinics, settings in which home-based health-care and emergency medical services are provided, and laboratories handling TB clinical samples.
HEPA filters (high efficiency particulate air filters) – special filters that can be used in ventilation systems to help remove droplet nuclei from personal respirators – special device designed to protect users from inhaling droplet nuclei; used in health care facilities and other settings where TB may be spread.
3) Respiratory-protection controls – the third level in the hierarchy of TB infection-control measures; used to minimize the risk for exposure to M. tuberculosis.
surgical mask – device worn over the nose and mouth of a person with suspected or confirmed infectious TB disease to prevent infectious droplet nuclei from being spread (exhaled) into the air.
Infectiousness is directly related to the number of tubercle bacilli the TB patient expels into the air. Patients who expel many tubercle bacilli are more infectious than patients who expel few or no bacilli.
The number of tubercle bacilli expelled by a TB patient depends on the following factors.
TB patients expel more tubercle bacilli if they have a cough that produces a lot of sputum.
Because there are many tubercle bacilli in a cavity, TB patients who have a cavity in the lung may be expelling large amounts of tubercle bacilli if they are coughing.
- Positive sputum smear result and/or culture
The presence of acid-fast bacilli on a sputum smear or a positive sputum culture indicates that the patient may be expelling many tubercle bacilli.
Usually, only people with TB of the lungs (pulmonary), airway, or larynx are infectious. This is because these people may be coughing and expelling tubercle bacilli into the air. People with extra pulmonary TB other than the airway and larynx (no pulmonary TB) generally are not infectious. This is because tubercle bacilli usually cannot be expelled into the air from a non-respiratory extra pulmonary site.
- Covering mouth and nose when coughing
Patients who do not cover their mouth when they cough are more likely to expel tubercle bacilli.
- Lack of or inadequate treatment
Patients who have NOT been receiving adequate TB treatment are much more likely to be infectious than patients who have been receiving adequate treatment for 2 weeks or longer. Patients who have been receiving adequate treatment usually respond to treatment; in other words, their symptoms improve and eventually go away.
- Cough-inducing procedures
Patients may expel tubercle bacilli if they are undergoing medical procedures that cause them to cough (for example, bronchoscopy or sputum induction).
Patients can be considered noninfectious when they meet all of the following criteria:
- They have been receiving adequate treatment for 2 weeks or longer.
- Their symptoms have improved (for example, they are coughing less and they no longer have a fever); and
- They have THREE consecutive negative sputum smears from sputum collected in 8-24 hour intervals (at least one being an early morning specimen).
TB Infection-Control Program Fundamentals
The main goals of a TB infection-control program are to ensure early and prompt
- Detection of TB disease.
- Isolation of people who have or are suspected of having TB disease (airborne precautions).
- Treatment of people who have or are suspected of having TB disease.
Developing an Infection-Control Program
A health care or congregate setting’s TB infection-control program should be based on a three-level hierarchy of control measures.
The three-levels of control include:
- Administrative controls.
- Environmental controls.
- Respiratory-protection controls.
- Assign responsibility for TB infection control
- Conduct TB risk assessment
- Develop and institute a written TB infection-control plan
- Ensure the timely availability of recommended laboratory processing, testing, and reporting of results
- Implement effective work practices for the management of patients with suspected or confirmed TB disease
- Ensure proper cleaning and sterilization or disinfection of potentially contaminated equipment
- Train and educate health care workers
- Test and evaluate health care workers for TB infection and disease
- Apply epidemiologic-based prevention principles
- Use posters and signs demonstrating and advising respiratory hygiene and cough etiquette
- Coordinate efforts with the local or state health department.
- Reduce concentration of infectious droplet nuclei through following technologies
- Ventilation technologies including Natural ventilation
- High efficiency particulate air filtration (HEPA)
- Ultraviolet germicidal irradiation (UVGI)
- Implement a respiratory protection program.
- Train health care workers on respiratory protection.
- Educate patients on respiratory hygiene and the importance of covering their cough.
Respirator N-95 Mask for Health Care Workers
Infection Control in the Home
Patients who are suspected or confirmed for having TB disease are frequently sent home after starting treatment, even though they may still be infectious. Patients with TB disease can be sent home even if they do not have three negative sputum smears, if the following criteria are met:
- A follow-up plan has been made with the local TB program;
- The patient is on standard TB treatment and directly observed therapy (DOT) has been arranged;
- No infants or children less than 4 years of age or persons with immunocompromising conditions are present in the household;
- All household members, who are not immunocompromised, have been previously exposed to the person with TB; and
- The patient is willing to not travel outside his/her home until he/she has negative sputum smear results.
If all of the above criteria are met, patients with TB disease are allowed to go back home. Additionally they are more likely to have already transmitted TB to members of their household before their TB was diagnosed and treatment was started.
However, TB patients and members of their household should still take steps to prevent the spread of TB in their home. For example, patients with TB should be instructed to cover their mouth and nose with a tissue when coughing or sneezing. Infectious TB patients should sleep alone, not in a room with other household members. Furthermore, TB patients should be advised to not have visitors until they are non-infectious.
Patients with infectious TB should not be allowed to return home where they may expose a person who is at high risk for progressing to TB disease if infected (for example, persons living with HIV, or infants and children). Health care workers in home-based health care or outreach settings should be trained on detecting the signs and symptoms of TB disease. Training should include the role of the health care worker in educating patients about the importance of reporting symptoms or signs. Health care workers should also educate patients and other household members about the importance of taking medications as prescribed.
Health care workers should not perform cough-inducing or aerosol-generating procedures on patients with suspected or confirmed infectious TB disease inside a patient’s home. Sputum collection should be performed outdoors, away from other persons, windows, or ventilation intakes.
Health care workers who visit TB patients at their homes should take these precautions to protect themselves from exposure to M. tuberculosis:
- Instruct patients to cover their mouth and nose with a tissue when coughing or sneezing;
- Wear a personal respirator when visiting the home of an infectious patient with TB or when transporting an infectious patient with TB in a vehicle;
- When it is necessary to collect a sputum specimen in the home, collect the specimen in a well-ventilated area, away from other household members; if possible, the specimen should be collected outdoors; and
- Participate in a TB testing and prevention program.