Table 8– Number of possibly effective drugs included in treatment regimens by extensively drug-resistant tuberculosis (XDR-TB) patient group
XDR aloneXDR+2sliXDR+sliG4XDR+sliG4EZ
Subjects301684842
Number of possibly effective drugs
 0–136 (12)10 (15)36 (75)35 (83)
 241 (14)23 (34)5 (10)2 (5)
 376 (25)15 (22)4 (8)3 (7)
 468 (23)9 (13)1 (2)0 (0)
 580 (27)11 (16)2 (4)2 (5)
  • Data are presented as n or n (%). Possibly effective means sensitive, or not tested for that drug. All group 5 drugs were considered possibly effective because no drug susceptibility testing was available for these drugs. Later generation fluoroquinolones were considered possibly effective, even though (by definition) all patients' isolates were resistant to fluoroquinolones. 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 (G4) drug; 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).