Table 2– Drugs to which Mycobacterium tuberculosis strains were resistant by extensively drug-resistant tuberculosis (XDR-TB) patient group
XDR aloneXDR+2sliXDR+sliG4XDR+sliG4EZ
Group 1
 Ethambutol222/280 (79)55/68 (81)30/30 (100)30/30 (100)
 Pyrazinamide138/230 (60)47/51 (92)32/32 (100)32/32 (100)
Group 2
 Fluoroquinolones#301/301 (100)68/68 (100)48/48 (100)42/42 (100)
Group 3
 Streptomycin208/292 (71)68/68 (100)27/27ƒ (100)26/26ƒ (100)
 Kanamycin/amikacin279/301 (93)68/68 (100)48/48 (100)42/42 (100)
 Capreomycin26/207 (13)68/68 (100)48/48ƒ (100)12/12ƒ (100)
 Resistant to kanamycin/amikacin and capreomycin14/301 (5)68/68 (100)12/12ƒ (100)12/12ƒ (100)
 Resistant to all injectables+0/301 (0)68/68 (100)12/12ƒ (100)12/12ƒ (100)
Group 4§
 Ethionamide or prothionamide138/257 (54)38/64 (59)47/47 (100)41/41 (100)
 Cycloserine or terizidone59/235 (25)12/59 (20)26/26 (100)26/26 (100)
 Para-aminosalycilic acid87/228 (38)26/56 (46)21/21 (100)21/21 (100)
 Resistant to less than half of group 4 drugs tested164 (63)40 (61)00
 Resistant to half or two-thirds of group 4 drugs tested60 (23)11 (17)00
 Resistant to all group 4 drugs tested38 (15)15 (23)48 (100)42 (100)
  • Data are presented as n, n/N (%) or n (%). No information was collected regarding group 5 drug susceptibility test results. XDR alone: resistance to isoniazid and rifampicin, plus any fluoroquinolone and any second-line injectable drug (sli); XDR+2sli: XDR-TB, plus resistance to both an aminoglycoside injectable (kanamycin/amikacin) and to capreomycin; XDR+sliG4: XDR-TB, plus resistance to all second-line TB drugs tested, with, as a minimum, resistance to kanamycin and to at least one group 4 drug (G4); XDR+sliG4EZ: XDR-TB, plus resistance to all first- and second-line TB drugs tested, with, as a minimum, resistance to kanamycin, one group 4 drug and either pyrazinamide (Z) and/or ethambutol (E). #: all patients were, by definition, resistant to fluoroquinolones as they all met the definition of extensive drug resistance. Nearly all laboratories reported a single result for fluoroquinolones susceptibility testing; generally for ofloxacin susceptibility. : kanamycin and amikacin susceptibility results are shown together because participating laboratories tested for one drug or the other but very few tested for both. Hence these results were considered equivalent. +: resistant to streptomycin, kanamycin, amikacin and capreomycin. §: group 4 drug resistance was categorised as: resistant to less than half of those tested; resistant to half or two-thirds of those tested; and resistant to all group 4 drugs tested. ƒ: in these groups, patients were resistant to all injectables tested, but the minimum requirement was that they were tested for susceptibility to kanamycin/amikacin. Hence many were not tested for susceptibility to capreomycin and/or streptomycin.