TABLE 1.
Resistance profiles, mutations, and MICs of four phenotypically INH-resistant but RMP-susceptible strainsa
| Strain | Resistance to first-line agents | inhA and katG mutationsb | INH susceptibility determined by MGIT 960 at MIC (μg/ml) of: |
rpoB mutation(s) | RMP susceptibility at indicated MIC (μg/ml) determined by: |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LJ medium |
MGIT 960 |
|||||||||||||||
| 0.1 | 1 | 3 | 10 | 1.25 | 2.5 | 5 | 10 | 20 | 40 | 0.25 | 0.5 | 1 | ||||
| 1 | INH, SM | −15 C/T, S315T | R | R | R | R | L533P | R | R | S | S | S | S | R | S | S |
| 2 | INH, SM | WT, S315T | R | R | S | S | D516Y, N518D | B | S | S | S | S | S | S | S | S |
| 3 | INH, EMB | −15 C/T, WT | R | S | S | S | L533P | R | R | R | S | S | S | R | S | S |
| 4 | INH | −8 T/A, S315T | R | R | R | R | E510H, D516Y | R | R | R | R | R | S | R | R | S |
a
Abbreviations: INH, isoniazid; SM, streptomycin; EMB, ethambutol; R, resistant; S, susceptible; B, borderline.
b
Designations such as −15 C/T indicate a C/T exchange at position −15. WT, wild type.