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Table 2 Performance of the Genotype MTBDRplus assay in detecting resistance in clinical isolates of Mycobacterium tuberculosis

From: Diagnostic accuracy and usefulness of the Genotype MTBDRplus assay in diagnosing multidrug-resistant tuberculosis in Cameroon: a cross-sectional study

Gold standard: BACTEC MGIT DST 960 System(# of Mtb isolates)
   RIF INH MDR-TB
Test assay   Resistant Susceptible aResistant Susceptible Resistant Susceptible
(n = 49) (n = 176) (n = 60) (n = 165) (n = 49) (n = 176)
MTBDRplus Resistant 48 0 55 1 46 0
Susceptible 1 176 5 164 3 176
Sensitivity (95% CI) 98 (89–100) 92 (82–96) 94 (83–98)
Specificity (95% CI) 100 (98–100) 99 (97–100) 100 (98–100)
PPV (95% CI) 100 (93–100) 98 (91–100) 100 (92–100)
NPV (95% CI) 99 (97–100) 97 (93–99) 98 (95–100)
Cohen’s kappa (95% CI) 0.99 (0.96–1.00) 0.93 (0.88–0.99) 0.96 (0.92–1.00)
  1. Abbreviations: CI Confidence interval, RIF Rifampicin, INH Isoniazid, MDR-TB Multidrug resistant Tuberculosis, PPV Positive Predictive Value, NPV Negative Predictive Value
  2. aINH Resistant (n = 60) refers to all INH resistant isolates that is; INH and RIF drug-resistant (n = 49), INH mono drug-resistant (n = 6) and INH poly drug-resistant (n = 5)