TB Manual

Medical masks include procedure masks and surgical masks. Either type of medical mask, when worn by patients with respiratory TB, serves as a source-control measure to trap infectious respiratory secretions and is not intended as a form of PPE for the wearer.⁷¹ Although there is concern that because masks are loose fitting they may allow the escape of aerosols (particularly during coughing), tight-fitting respirators may be uncomfortable for patients (particularly those with limited respiratory reserve) and are therefore not recommended for source control.

Airborne precautions for a patient with symptoms of respiratory TB can be discontinued once suspicion of TB is appropriately excluded, based on results of microbiological investigation and establishment of an alternate diagnosis.

Although the degree and duration of infectiousness of patients after initiation of effective therapy remains unclear, it is known that effective therapy will rapidly reduce cough and the number of viable mycobacteria in the sputum. In patients who are no longer able to spontaneously produce a sputum specimen, sputum induction is useful and appropriate. A poor response to therapy should raise the possibility of drug resistance, even before susceptibility results are available, and inform the decision on discontinuing precautions.

Most people with respiratory TB can be managed in the outpatient setting. If hospitalization is needed, patients with TB are not necessarily required to remain in hospital until no longer infectious. While smear-positive patients are still potentially infectious, their household contacts have already been exposed and are often receiving therapy for latent TB infection when discharge from hospital is being considered. The risk of transmission to these contacts should be balanced by the social, mental and physical health benefits of the patient’s return home. Patients with TB should be discharged as soon as there is no further medical indication to continue hospitalization and criteria for home isolation are met (see Appendix B: De-isolation Review and Recommendations).

On the one hand, there is no evidence of TB being transmitted from persons who have received at least 2 weeks of effective anti-TB therapy. On the other hand, the evidence of no transmission is of poor quality. Given the uncertainty that arises from poor evidence and the potential exposure of highly susceptible contacts (e.g., very young children or highly immune-compromised patients), especially within the acute care hospital setting, the decision to discontinue airborne precautions is individualized. As such, airborne precautions may be continued for a longer period of time in hospital, where many patients are immune-compromised, than is the case in community settings.

Recommendations

• We strongly recommend initiating airborne precautions immediately for all those with, or being evaluated for, respiratory TB, both in the healthcare setting and in a long-term care home (good evidence).

• For hospitalized patients being evaluated for respiratory TB, we strongly recommend that criteria for discontinuing airborne precautions in hospitalized adolescents and adults include three consecutive smear-negative sputum samples and an alternative diagnosis that explains the patient’s condition and eliminates suspicion of TB; discontinuation of airborne precautions in hospitalized children cannot be based on negative gastric aspirate smears alone (good evidence).

Good practice statements

• When availability of airborne infection isolation rooms is limited, priorities for placement of patients should be determined by a risk assessment.

  • Patients with, or being evaluated for, respiratory TB should have priority over most other indications for an airborne infection isolation room and should not share rooms with each other.

• In the absence of an airborne infection isolation room, the patient/resident with, or being evaluated for, respiratory TB should be placed in a single room (with the door closed and a portable high-efficiency particulate air filtration unit used if available) and instructed to wear a medical mask until and during transfer to a facility or unit where an airborne infection isolation room is available.

• In the absence of an airborne infection isolation room and when outdoor temperature permits, use natural ventilation to assist in reducing the risk of transmission of airborne pathogens.

• Airborne precautions include the use of respirators by health care workers in direct contact with patients/residents with, or being evaluated for, active respiratory TB.

• Institutional policies should designate Infection Prevention and Control personnel with the authority to discontinue airborne precautions, as well as to manage both breaches of and adherence to airborne precautions.

• The patient should remain in the airborne infection isolation room until airborne precautions are discontinued by designated personnel; patients on airborne precautions may leave the airborne infection isolation room for medical reasons provided they wear a medical mask.

• Patients should be discharged home as soon as there is no further medical indication to continue hospitalization and criteria for home isolation are met.

• Institutional policies should specify the criteria for discontinuing airborne precautions for patients who need continuing hospital care:

  • Hospitalized patient with confirmed respiratory TB

    • Smear-negative, rifampin-susceptible: Airborne precautions can be discontinued once there is clinical evidence of improvement and a minimum of two weeks of effective therapy has been completed.

    • Smear-positive, rifampin-susceptible: Airborne precautions can be discontinued once there is clinical evidence of improvement, a minimum of 2 weeks of effective therapy has been completed and there are 3 consecutive negative acid-fast bacilli sputum smears.

    • Persistent smear-positive, rifampin-susceptible: Discontinuing airborne precautions may be considered once there is clinical evidence of improvement and a minimum of 4 weeks of effective therapy has been completed.

    • Confirmed or suspect rifampin-resistant: Discontinuing airborne precautions may be considered once there is clinical improvement, second-line drug susceptibility results are available, a minimum of 4 weeks of effective therapy has been completed and, for those initially smear-positive, three consecutive sputum smears are negative.

• Discharge to home of any patient presumed to be still infectious should be co-ordinated with the patient’s TB physician and local public health authorities to ensure that:

  • follow-up of household members and home measures to protect any vulnerable individuals are in place, and

  • patients are not being discharged to a setting where they would expose previously unexposed individuals or a large number of people (e.g., congregate settings).

4.1.5. Transport of patients with, or being evaluated for, respiratory TB

There is a potential for exposure to, and transmission of, TB during patient transport that can be prevented by applying appropriate IPC measures.

Good practice statements

• Prior to transport, health care workers involved in patient transport, transport personnel and the receiving healthcare facility should be advised of the need for airborne precautions.

• If transport between facilities is required, or for infectious patients traveling to outpatient appointments, patients should not use public transportation (e.g., buses, ride share services, commercial flights).

• Patients should be transported in well-ventilated vehicles (ie, with the windows open when possible).

• Where air transport is required (e.g., from remote settings), transport personnel should refer to their organization’s policies on medical transport of patients with respiratory TB.

4.1.6. Education of health care workers

An important component of any TB IPC Program is HCW education on how to recognize and protect themselves from exposure to M. tuberculosis. This includes information on epidemiologic and medical risk factors for TB, signs and symptoms of TB (respiratory and non-respiratory), mechanisms of transmission and principles of control.⁷²

Recommendations

• We conditionally recommend that all health care workers receive education on TB that is relevant to their work activity, both at the time of hiring and periodically thereafter (poor evidence).

• We conditionally recommend that all health care workers be educated on the principles of engineering, administrative (including signage) and personal protective equipment controls in the prevention of transmission of TB and how to apply them (poor evidence).

4.1.7. Health care worker testing and treatment for TB infection

The importance of conducting a baseline HCW assessment for the presence of latent TB infection cannot be overemphasized. At the time of employment, there may be HCWs with latent TB infection because of prior exposure, particularly the situation for HCWs born or previously living in high-TB-incidence countries (see Appendix 2, Table 2a).^4,6,37,73 Foreign-born HCWs represent an increasing proportion of the workforce in Canadian hospitals and long-term care homes.⁷⁴ HCWs with reactivation of a latent TB infection can be a source of TB transmission in the healthcare setting where they work.^6,75 As per the evidence summary in Appendix 1, Tables 1a and 1b, 7 out of 16 identified exposure events were due to an index HCW case. Testing and treating for TB infection is expected to reduce this source of exposures.

Historically, the tuberculin skin test (TST) has been the standard for making a diagnosis of latent TB infection. More recently, interferon-gamma release assays (IGRAs) have been introduced as another diagnostic test. However, the use of IGRA for serial (repeated) testing of HCWs is not recommended because serial-testing studies have shown high rates of conversions and reversions, unrelated to exposure or treatment (see Chapter 4: Diagnosis of Tuberculosis Infection).

Prior exposure to M. tuberculosis or Bacille Calmette-Guérin (BCG) vaccination can result in a boosting phenomenon due to immune recall to a mycobacterial antigen, which may be misdiagnosed as a TST conversion. Interpreting a positive TST performed as part of contact tracing in response to a potential TB exposure in an individual with preexisting latent TB infection or BCG vaccination and for whom an employment test result is unknown can incorrectly over-count TST conversions in relation to a healthcare exposure event. Therefore, a 2-step TST is recommended to establish baseline (see Chapter 4: Diagnosis of Tuberculosis Infection).^4,76

Studies from the United States and the United Kingdom indicate that HCWs in low-incidence countries are at no higher risk for TB than the general population, when adjusted for country of origin (see Appendix 2,Table 2b ).^4,6,77 As such, there is no indication for routine organization-wide periodic TST of all HCWs.^29,76 Periodic screening (e.g., annual testing) of HCWs at higher risk for occupationally acquired TB, based on the organization risk assessment, may be warranted. Examples of such situations might be HCWs working in bronchoscopy suites or on units identified as having exposure episodes.

Any HCW identified as having had unprotected exposure (termed an exposure episode) to a patient/resident/client or coworker confirmed to have respiratory TB disease should be assessed for TB infection (see See section 9 in this chapter and Chapter 11: Tuberculosis Contact Investigation and Outbreak Management).

Recommendations

• We strongly recommend that all health care workers should have a baseline TB screening, including:

  1. an individual risk assessment that identifies risks for TB (temporary or permanent residence in a high-incidence country, prior TB, current or planned immune suppression or close contact with someone who has had infectious TB since the last tuberculin skin test);

  2. a symptom evaluation; and

  3. a tuberculin skin test for those without documented prior TB disease or latent TB infection (good evidence).

• We strongly recommend against routine periodic TB testing of all health care workers with negative baseline tuberculin skin test (good evidence).

Good practice statements

• The tuberculin skin test is the preferred diagnostic test for pre-employment and periodic testing (if indicated) for TB infection among health care workers.

• While volunteers should be screened for risk factors for latent TB infection, consideration could be given to performing a tuberculin skin test only in those who expect to volunteer at least one-half day/week or who have risk factors for latent TB infection.

• A baseline 2-step tuberculin skin test should be done unless there is documentation of a prior negative 2-step test, in which case a single-step test should be done, and all results entered into the health care worker’s health record.

• All health care workers with a positive tuberculin skin test should be assessed for active TB disease, including a chest x-ray and a medical evaluation, including consideration for treatment of TB infection by a physician experienced in management of TB and latent TB infection; they should also be educated on the signs and symptoms of TB.

• A tuberculin skin test should not be performed on a health care worker who was previously TST-positive or has prior documented TB disease.

• Health care organizations can consider whether periodic screening for selected health care workers is warranted based on their organizational risk assessment.

• Symptom evaluation for all health care workers should be performed by Occupational Health Safety and Wellness when an exposure is recognized and referral for medical assessment be made as required.

• The health care worker with a baseline negative tuberculin skin test should have another such test 8 weeks after exposure.

• Treatment of health care workers with latent TB infection is encouraged in the absence of contraindications to the recommended medications.