Gene Xpert MTBRIF assayn117 Smear Culture ve Gene
Gene. Xpert MTB/RIF assay(n=117) Smear + / Culture +ve Gene xpert + ve 75 (64%) (Live bacilli) (37 Pulm & 48 EPTB) Smear & Culture - ve Gene xpert +ve 37 (32%) (Dead bacilli) Smear & Culture + ve Gene xpert -ve 5 (4%) (Atypical Mycobacteria)
GENE XPERT PERFORMANCE SPUTUM (n = 54) Gold Standard Gene xpert+ve Gene xpert - ve Culture+ve 15 (T+ve) 0 (F-ve) Aty Mb Culture -ve 5 (F +ve) Dead 34 (T –ve)
GENE XPERT PERFORMANCE BRONCHIAL WASH (n = 52) Gold Standard Gene xpert+ve Gene xpert - ve Culture+ve 12 (T+ve) 0 (F-ve) Aty Mb Culture -ve 3 (F +ve) Dead 37 (T –ve)
GENE XPERT PERFORMANCE Extra-Pulmonary Samples (n=153) Specimen No. C+ ve Ge. X +ve Sensitivity (%) Specificity(%) PPV(%) NPV (%) CSF 78 4 100 89. 19 33. 3 100 Asp. Pus Tissue (bon) 26 18 100 52. 63 43. 75 100 23 11 100 78. 95 50 100 Lymph node 26 15 100 63. 64 33. 3 100
Extra-Pulmonary Samples – Culture & Gene. Xpert Negative (n=61) SPECIMEN NO. Pleural fluid 26 Ascitic fluid 22 Synovial fluid 6 Aspirated fluid 5 Pericardial fluid 1 Peritoneal fluid 1
GENE XPERT PERFORMANCE-Sensitivity • Analytical sensitivity • 5 genome copies of purified DNA • 131 CFU/ml of M. tb • Sensitivity = 100% • Negative Predictive value = 100% • Test accuracy = 100% • (detected all smear +ve / Culture +ve)
GENE XPERT PERFORMANCE -Specificity Specimen Specificity (%) PPV (%) Sputum 87 75 Bronchial wash 93 80 CSF 90 33 Asp. Pus 53 44 Tissue (bone) 79 50 Lymph node 64 33 32% Dead bacilli - Already treated cases ? ?
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