TABLE 2.
Drug susceptibility testing by different methodology in a case of acquired drug resistance while on a standardized MDR-TB regimen
| Medicationa | Pretreatment | During treatment |
|---|---|---|
| Ofloxacin | ||
| APM | Susceptible | NAb |
| MGIT 960 | Susceptible | Resistant |
| MIC (breakpoint, 2.0 μg/ml) (μg/ml) | 4.0 | 8.0 |
| Moxifloxacin | ||
| APM | NA | NA |
| MGIT 960 | Susceptible | Resistant |
| MIC (breakpoint, 1.0 μg/ml) (μg/ml) | 2.0 | 4.0 |
| Kanamycin | ||
| APM | Susceptible | NA |
| MGIT 960 | Susceptible | Resistant |
| MIC (breakpoint, 5.0 μg/ml) (μg/ml) | 1.2 | 20.0 |
| Amikacin | ||
| APM | NA | NA |
| MGIT 960 | NA | NA |
| MIC (breakpoint, 4.0 μg/ml) (μg/ml) | 0.25 | >16.0 |
| Ethionamide | ||
| APM | NA | NA |
| MGIT 960 | Resistant | Resistant |
| MIC (breakpoint, 5.0 μg/ml) (μg/ml) | 40.0 | 10.0 |
| p-Aminosalicylic acid | ||
| APM | NA | NA |
| MGIT 960 | Susceptible | Susceptible |
| MIC (breakpoint, 2.0 μg/ml) (μg/ml) | ≤0.5 | 2.0 |
| Cycloserine | ||
| APM | NA | NA |
| MGIT 960 | NA | NA |
| MIC (breakpoint, 16.0 μg/ml) (μg/ml) | 16.0 | 32.0 |
| Pyrazinamide | ||
| APM | NA | NA |
| MGIT 960 | Resistant | Resistant |
| MIC | NA | NA |
a
APM, agar proportion method on solid agar at the national referral laboratory. The proposed breakpoints are for MIC testing on the MycoTB plate whereby visible growth at the concentration represents conventional resistance.
b
NA, not available.