Article Figures & Data
Tables
- TABLE 1.
Reproducibility testing
Drug (concn in μg/ml) No. of tests performeda No. of results agreeing with reference method (BACTEC 460 TB) Agreement (%) INH (0.1) 170 170 100 INH (0.4) 170 165 97.1 RIF (1.0) 170 169 99.4 EMB (5.0) 170 170 100 EMB (7.5) 167 166 99.4 STR (1.0) 170 169 99.4 STR (4.0) 170 170 100 S Total of tests 1,187 1,179 99.3 ↵ a Center 1, 10 strains in duplicate at three different times (thus, six replicates per strain); center 2, 10 strains in triplicate at three different times (thus, nine replicates per strain); and center 3, 10 strains in triplicate (thus, two replicates per strain).
- TABLE 2.
Drug susceptibility results of clinical strains of M. tuberculosis as determined by BACTEC MGIT 960 and BACTEC 460 TB systema
Drug (concn in μg/ml) No. of tests No. of results that were: Agreement (%) S by both tests R by MGIT 960; S by 460 TB S by MGIT 960; R by 460 TB R by both tests INH (0.1) 110 81 4 25 96.4 INH (0.4) 29 5 3 21 89.7 RIF (1.0) 110 92 1 17 99.1 EMB (5.0) 110 93 3 1 13 96.4 EMB (7.5) 17 7 3 7 82.4 STR (1.0) 110 76 9 25 91.8 STR (4.0) 34 12 10 12 70.6 Total of tests 520 366 33 1 120 93.5 ↵ a S, susceptible; R, resistant.
- TABLE 3.
Resolution of discrepant results by proportion method on solid LJ mediuma
Drug (concn in μg/ml) Initial results for: Resolved resultsb for: R by MGIT 960; S by 460 TB S by MGIT 960; R by 460 TB R by MGIT 960 and PM (true resistant) S by MGIT 960 and PM (true susceptible) R by MGIT 960; S by PM (false-resistant ME) INH (0.1) 4 1 3 INH (0.4) 3 1 2 RIF (1.0) 1 1 0 EMB (5.0) 3 1 0 1 3 EMB (7.5) 3 1 2 STR (1.0) 9 1 8 STR (4.0) 10 6 4 Total of tests 33 1 11 1 22 - TABLE 4.
Accuracy of BACTEC MGIT 960 compared with that of BACTEC 460 TB system after resolution of discrepanciesa
Drug (concn in μg/ml) Sensitivity (%) Specificity (%) PPV (%) NPV (%) INH (0.1) 100 96.4 89.7 100 INH (0.4) 100 97.7 91.7 100 RIF (1.0) 100 100 100 100 EMB (5.0) 100 96.9 81.3 100 EMB (7.5) 100 98.0 80 100 STR (1.0) 100 90.5 76.5 100 STR (4.0) 100 89.8 81.2 100 ↵ a PPV, positive predictive value; NPV, negative predictive value.
- TABLE 5.
Time required for drug susceptibility testing of M. tuberculosis
No. of strains Time (days) required for: MGIT 960 460 TB Median Range Median Range 85a 6.3 4.6–11.7 7.0 4.0–10.0 25 7.1 5.7–10.9 5.0 5.0–7.0 110 6.5 4.6–11.7 7.0 4.0–10.0 ↵ a Eighty-five strains were from center 1; 25 from center 2; and 110 from centers 1 and 2.
