Definitions
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Definitions
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
Extensive (or advanced) tuberculosis (TB) disease: presence of bilateral cavitary disease or
extensive parenchymal damage on chest radiography. In children aged under 15 years, advanced
disease is usually defined by the presence of cavities or bilateral disease on chest radiography.
Extensively drug resistant TB (XDR-TB): TB that is resistant to any fluoroquinolone and to at least
one of three second-line injectable drugs (capreomycin, kanamycin and amikacin), in addition to
multidrug resistance.
2
Longer multidrug-resistant TB (MDR-TB) regimens: used for treatment of multidrug- or rifampicin-
resistant TB (MDR/RR-TB), these regimens last 18 months or more, and are
designed using a hierarchy
of recommended medicines, including a minimum number of medicines considered to be effective
based on drug-resistance patterns or patient history. The features and indications of these regimens
are further elaborated in the Recommendations in these
guidelines.
MDR-TB:
TB caused by Mycobacterium Tuberculosis (M. tuberculosis) strains that are resistant to at
least both rifampicin and
isoniazid.
New case: a newly registered episode of TB in a patient who has never
been treated for TB or has
taken anti-TB medicines for less than 1
month.
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