TABLE 1.

Test results for clinical strains of M. tuberculosis (n = 200) for susceptibility to SIRE and PZA

Antibiotic (concn [μg/ml])MGIT 960 resultaRRM resultaOverall agreement (%)Sensitivityb (%)Specificityc (%)PPVd (%)NPVe (%)
SR
STR (1.0)S376979610010086
R157
STR (4.0)S8216928610010084
R102
INH (0.1)S303f999810010091
R167
INH (0.4)S313f999810010091
R166
RIF (1.0)S68100100100100100
R132
EMB (5.0)S10371652710010059
R26
EMB (7.5)S15633842510010083
R11
PZA (100)gS15889277989095
R326
  • a S, susceptible; R, resistant. Values are numbers of isolates.

  • b The sensitivity, i.e., the ability of MGIT 960 to detect true resistance compared with the RRM results.

  • c The specificity, i.e., the ability of MGIT 960 to detect true susceptibility compared with the RRM results.

  • d PPV, positive predictive value.

  • e NPV, negative predictive value.

  • f Mixed cultures (consisting of resistant and susceptible subpopulations).

  • g Five M. tuberculosis isolates did not grow in one of the systems used.