TABLE 1.
GIs and CFU counts of M. tuberculosis H37Rv in INH and RIF susceptibility testing by the BACTEC 460 methoda
| Drug, concn (μg/ml), and culture | GI at day:
|
Final count (CFU/ml) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8b | 15b | 22b | 28b | ||
| INH, 0.1 | ||||||||||||
| Control | 3 | 0 | 1 | 3 | 7 | 15 | 22 | 37 | ||||
| Wk 1 | 16 | 12 | 8 | 6 | 4 | 6 | 5 | 5 | 1.2 × 103 | |||
| Wk 2 | 20 | 14 | 10 | 8 | 7 | 9 | 5 | 5 | 18 | 3.1 × 103 | ||
| Wk 3 | 18 | 13 | 8 | 7 | 4 | 7 | 4 | 4 | 19 | 72 | 2.4 × 104 | |
| Wk 4 | 16 | 11 | 7 | 8 | 3 | 5 | 3 | 3 | 17 | 60 | 251 | 1.22 × 105 |
| INH, 0.4 | ||||||||||||
| Control | 3 | 0 | 1 | 3 | 7 | 15 | 22 | 37 | ||||
| Wk 1 | 15 | 9 | 0 | 6 | 4 | 5 | 4 | 2 | 55 | |||
| Wk 2 | 18 | 12 | 9 | 8 | 6 | 7 | 6 | 5 | 17 | 3.6 × 103 | ||
| Wk 3 | 17 | 10 | 7 | 6 | 4 | 6 | 5 | 4 | 14 | 93 | 1.45 × 104 | |
| Wk 4 | 15 | 11 | 8 | 7 | 4 | 0 | 4 | 3 | 9 | 36 | 106 | 1.32 × 104 |
| RIF, 2 | ||||||||||||
| Control | 3 | 0 | 1 | 3 | 7 | 15 | 22 | 37 | ||||
| Wk 1 | 10 | 5 | 3 | 1 | 0 | 1 | 0 | 0 | 0 | |||
| Wk 2 | 11 | 8 | 3 | 2 | 0 | 1 | 2 | 0 | 0 | 0 | ||
| Wk 3 | 10 | 6 | 2 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | |
| Wk 4 | 15 | 4 | 2 | 2 | 0 | 1 | 0 | 0 | 0 | 2 | 0 | 0 |
a
M. tuberculosis H37Rv was inoculated into vials containing 0.1 or 0.4 μg/ml INH or 2 μg/ml RIF and incubated at 37°C for 4 weeks. GI values were measured daily within the first week and then weekly for 4 weeks. Colony counts were measured once a week by taking aliquots from each vial and plating on solid media without antibiotic. The beginning CFU for this experiment is 2.0 × 104.
b
Time when a culture vial was taken out and subcultures and colony counts were made.