Home1.3.1. Healthcare settings
The risk of healthcare-associated transmission of M. tuberculosis to HCWs, patients/residents and visitors varies with the type of setting, occupational group, effectiveness of TB IPC measures and patient/resident population. Previous Canadian guidance provided thresholds for annual numbers of patients admitted with respiratory TB that could be used by facilities to determine their risk for healthcare-associated transmission of TB and guide their IPC interventions. Given the annual number of TB cases alone may not accurately reflect risk and that other factors such as effectiveness of IPC measures must be taken into account,43 this type of risk classification may no longer be suitable. A review of the community profile of TB disease and the number of TB admissions in the course of a year, independent of a risk-classification scheme, should inform determination of a healthcare facility and unit risk category as a framework to predict whether and where their HCWs are at increased risk of TB exposure and guide their IPC strategies.
1.3.2. Health care worker activities
Patient-care activities are associated with varying degrees of exposure risk and subsequent infection with M. tuberculosis. Performing high-risk procedures and activities are contributing factors to transmission of M. tuberculosis.16 The risk of transmission increases with the duration of exposure and higher amounts of airborne mycobacteria. As a result, it is recommended that HCWs perform a risk assessment prior to interactions with all patients, including people with confirmed TB or who have symptoms of TB.45 This risk assessment involves evaluating the likelihood of exposure to M. tuberculosis for a specific patient-care activity, with a specific patient, in a specific environment and under particular conditions. This is referred to as a point-of-care risk assessment and is described in the Public Health Agency of Canada’s (PHAC’s) Routine Practices and Additional Precautions for Preventing the Transmission of Infection in Healthcare Settings.45 The point-of-care risk assessment informs HCWs’ decisions regarding the IPC measures needed to minimize the risk of exposure for themselves, other HCWs, patients and visitors.
1.3.2.1. High-risk activities
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Aerosol-generating medical procedures (such as sputum induction, intubation, bronchoscopy)
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High-pressure irrigation of M. tuberculosis infected wounds
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Autopsy
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Morbid/pathologic anatomy
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Mycobacteriology laboratory procedures, especially handling cultures of M. tuberculosis
1.3.2.2. Intermediate-risk activities
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Work requiring regular, direct patient contact on units (including emergency departments as well as inpatient pediatric, neonatal, adult respiratory, medicine and thoracic surgery wards) where patients with respiratory TB may be present (this includes work done by all HCWs in these units).
1.3.2.3. Low-risk activities
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Work requiring minimal patient contact (such as clerical, reception and administration).
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Work on units where patients with respiratory TB disease are unlikely to be present.
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Classification of such units as low risk may be inaccurate if the population they are serving has a high incidence of TB (e.g., patients born or previously residing in countries with a high-TB incidence or other at-risk populations). Some of the longest delays in diagnosis may occur in such settings.14,22
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Risk can be mitigated by use of engineering and administrative controls and appropriate personal protective equipment (PPE).
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