TABLE 4.
M. tuberculosis bacilli that reactivate late in the variant C model are phenotypically altered, and the rate of reactivation is not increased by dexamethasone treatmenta
| Day of treatment | Group | Mouse no. | CFU in:
|
AFBc | Growth in 7H9 | IS6110 PCR | |
|---|---|---|---|---|---|---|---|
| Spleen | Lung | ||||||
| 50 | DEX | 1 | 416 | 1,296 | − (lung) | − | + |
| 2 | 0 | 0 | NAb | NA | NA | ||
| 3 | 0 | 0 | NA | NA | NA | ||
| 4 | 0 | 0 | NA | NA | NA | ||
| Control | 1 | 0 | 0 | NA | NA | NA | |
| 2 | 0 | 0 | NA | NA | NA | ||
| 3 | 0 | 0 | NA | NA | NA | ||
| 4 | 0 | 0 | NA | NA | NA | ||
| 80 | DEX | 1 | 0 | 40 | + | + | + |
| 2 | 276 | 0 | + | + | + | ||
| 3 | 0 | 0 | NA | NA | NA | ||
| 4 | 0 | 0 | NA | NA | NA | ||
| Control | 1 | 3,176 | 0 | + | + | + | |
| 2 | 0 | 40 | − | − | + | ||
| 3 | 0 | 0 | NA | NA | NA | ||
a
Mice were infected with M. tuberculosis for 4 weeks, treated with INH-PZA for 12 weeks, rested for 11 weeks, and then treated with normal rat IgG for 16 weeks before treatment with dexamethasone (DEX) (0.08 mg/day; s.c.) or with PBS s.c. The limit of detection for CFU determination was 10 CFU/organ. −, negative; +, positive.
b
NA, not applicable.
c
AFB, acid-fast bacillus staining.