Definitions and Categories of Resistant Tuberculosis
Categories of resistant tuberculosis Microbiologically confirmed: when a biological specimen is positive by smear microscopy, culture, or a rapid diagnostic test for Mycobacterium tuberculosis (M. tuberculosis) recommended by the World Health Organization (WHO). This is also referred to as bacteriologically confirmed. Clinically diagnosed: when a person who does not fulfil the criteria for bacter
Categories of resistant tuberculosis
Microbiologically confirmed: when a biological specimen is positive by smear microscopy, culture, or a rapid diagnostic test for Mycobacterium tuberculosis (M. tuberculosis) recommended by the World Health Organization (WHO). This is also referred to as bacteriologically confirmed.
Clinically diagnosed: when a person who does not fulfil the criteria for bacteriological confirmation has been diagnosed with TB by a medical practitioner who has decided to give the person a full course of RR-TB treatment.
New case: a person with TB disease who has never been treated for TB or has only previously ever taken TB drugs for less than 1 month.
Drug-resistant tuberculosis (DR-TB) refers to tuberculosis disease caused by Mycobacterium tuberculosis bacilli that are resistant to one or more anti-TB drugs. Case definitions [6,8,9] and outcome definitions have recently been revised [9].
Categories of resistant tuberculosis
- Mono-resistant TB: resistance to only one anti-TB drug, without resistance to other drugs.
- Poly-drug resistant TB: resistance to more than one anti-TB drug, other than both isoniazid and rifampicin.
- Multidrug-resistant TB (MDR-TB): resistance to isoniazid and rifampicin with or without resistance to other anti-TB drugs.
- Rifampicin resistant TB (RR-TB): resistance to at least rifampicin, with or without resistance to other drugs. This category includes MDR-TB, rifampicin mono-resistant TB, pre-XDR-TB and XDR-TB.
- Pre-Extensively drug-resistant TB (Pre XDR-TB): TB disease caused by strain of Mycobacterium tuberculosis (M. tuberculosis) complex that is resistant to rifampicin (and may also be resistant to isoniazid), and that is also resistant to fluoroquinolones.
- Extensively drug-resistant TB (XDR-TB): TB disease caused by a strain of Mycobacterium tuberculosis (M. tuberculosis) complex that is resistant to rifampicin (and may also be resistant to isoniazid), and that is also resistant to at least one fluoroquinolone (levofloxacin or moxifloxacin) and to at least one additional Group A drug either BDQ or LZD.
- Extensive (or advanced) pulmonary TB disease: presence of bilateral cavitary disease or extensive parenchymal damage on chest radiography. In children aged below 15 years, severe disease is defined by presence of cavities, parenchymal involvement of more or equal to one full lobe, miliary pattern, or mediastinal lymphadenopathy with airway compression on chest radiography.
- Severe extrapulmonary TB: meningitis, pericarditis, osteoarticular, abdominal or disseminated/miliary disease. In children aged below 15 years, severe EPTB is any extrapulmonary forms of disease other than lymphadenopathy (peripheral nodes) or simple pleural effusion.
Of note, throughout this document, the term “RR-TB” will be used as a general term to encompass all the forms of RR-TB (including MDR-TB, pre-XDR-TB, XDR-TB). When a more specific type of RR-TB is being discussed, it will be referred to in more detail (e.g. “rifampicin mono-resistant TB”; “fluoroquinolone-resistant RR-TB”).
National Department of Health Clinical Management of Rifampicin-Resistant Tuberculosis, September 2023
Definitions