Table 1

Evaluation of the ligase chain reaction (LCx) assay in culture confirmed Mycobacterium tuberculosis infection

Culture positive for M tuberculosis (n = 131)Culture negative for M tuberculosis (n = 1989)
Specimens (no.)LCx positiveLCx negativeLCx positiveLCx negative Sensitivity (%)Specificity (%)PPV (%)NPV (%)
*Sixty eight were contaminated cultures.
**Nine were positive by culture for non-tuberculous mycobacteria; six were culture negative.
NPV, negative predictive value; PPV, positive predictive value.
All (2120)10922331956*85.698.479.998.9
Smear positive (114)9117 15**98.975.992.995.7
Smear negative (2006)182126194165.098.760.098.9
Respiratory (2058)912133191384.298.377.298.9
Non-respiratory (49)5104385.7100.0100.097.7
Quality control (13)10003100.0100.0100.0100.0