Adverse event: Any untoward medical occurrence that may present in a person with tuberculosis (TB) during treatment with a pharmaceutical product but that does not necessarily have a causal relationship with the treatment.

Bacteriologically confirmed TB case: A case from whom a biological specimen is positive by smear microscopy, culture or a World Health Organization (WHO) recommended rapid diagnostic (e.g. Xpert® MTB/RIF).

Drug susceptibility testing (DST): In vitro testing using either molecular, genotypic techniques to detect resistance-conferring mutations, or phenotypic methods to determine susceptibility to a medicine.¹

Drug-susceptible TB (DS-TB): A bacteriologically confirmed or clinically diagnosed case of TB, without evidence of infection with strains resistant to isoniazid and rifampicin.

Extensive (or advanced) pulmonary TB disease: The presence of bilateral cavitary disease or extensive parenchymal damage on chest radiography (CXR). In children aged under 15 years, advanced disease is usually defined by the presence of cavities or bilateral disease on CXR.

Multidrug-resistant TB (MDR-TB): TB caused by Mycobacterium tuberculosis strains that are resistant to at least both isoniazid and rifampicin.

Multidrug- or rifampicin-resistant TB (MDR/RR-TB): The term used in this handbook and elsewhere to group MDR-TB and RR-TB cases; both MDR-TB and RR-TB cases are eligible for treatment with MDR-TB regimens. MDR/RR-TB usually refers to all patients affected by either MDR-TB or RR-TB.

Non-severe pulmonary TB: A form of TB defined as intrathoracic lymph node TB without airway obstruction; uncomplicated TB pleural effusion; or paucibacillary, non-cavitary disease confined to one lobe of the lungs and without a miliary pattern.

Rifampicin-resistant TB (RR-TB): TB caused by M. tuberculosis strains that are resistant to rifampicin. RR-TB strains may be susceptible to isoniazid or resistant to it (i.e. multidrug-resistant TB), or resistant to other first-line or second-line TB medicines.

Serious adverse event: An adverse event that leads to death or a life-threatening experience, to hospitalization or prolongation of hospitalization, to persistent or significant disability, or to a congenital anomaly. Includes adverse events that do not immediately result in one of these outcomes but that require an intervention to prevent such an outcome from happening.

Severe extrapulmonary TB: The presence of disseminated (miliary) TB or tuberculous meningitis. In children aged under 15 years, extrapulmonary forms of disease other than lymphadenopathy (peripheral nodes or isolated mediastinal mass without compression) are considered as severe.

Treatment support: Used here to describe an approach to supporting patients who are taking prescribed doses of TB medicines, to help ensure adherence to treatment and maximize its efficacy. Treatment support needs to be provided in the context of people-centred care and should be based on the individual patient’s needs, acceptance and preferences. It includes aspects of support, motivation and understanding of patients without coercion. Historically, this group of interventions were labelled as “directly observed treatment”

¹ Implementing tuberculosis diagnostics: a policy framework. Geneva: World Health Organization; 2015 (

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