TABLE 3.
Antimicrobial susceptibility testing of reference strains of rapidly growing mycobacteria by checkerboard broth microdilution methoda
| Mycobacterial strain | Rifabutin + clarithromycin |
Rifabutin + amikacin |
Rifabutin + cefoxitin |
Rifabutin + ceftibuten |
Rifabutin + clofazimine |
Rifabutin + doxycycline |
Rifabutin + linezolid |
Rifabutin + moxifloxacin |
Rifabutin + imipenem |
Rifabutin + tigecycline |
||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | MIC (mg/liter) |
FICI | |||||||||||||||||||||||||||||||
| A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | A | a | B | b | |||||||||||
| M. abscessus subsp. abscessus ATCC 19977 | 32 | 32 | 0.5 | 0.5 | 2 | 32 | 4 | 32 | 8 | 0.38 | 32 | 32 | >256 | >256 | 2 | 32 | 16 | 256 | 128 | 1 | 32 | 16 | 2 | 1 | 1 | 32 | 32 | >64 | >64 | 2 | 32 | 16 | 64 | 32 | 1 | 32 | 32 | 16 | 32 | 3 | 32 | 8 | 16 | 4 | 0.5 | 32 | 8 | 0.5 | 0.12 | 0.49 |
| M. abscessus subsp. bolletii BCRC 16915 | 16 | 2 | 4 | 0.25 | 0.19 | 16 | 8 | 32 | 16 | 1 | 16 | 16 | 32 | 32 | 2 | 16 | 4 | 256 | 128 | 0.75 | 16 | 16 | 2 | 2 | 2 | 16 | 16 | >64 | >64 | 2 | 16 | 8 | 64 | 32 | 1 | 16 | 16 | 32 | 32 | 2 | 16 | 1 | 16 | 0.5 | 0.09 | 16 | 2 | 0.5 | 0.06 | 0.25 |
| M. abscessus subsp. massiliense BCRC 16916 | 8 | 2 | 0.5 | 0.25 | 0.75 | 8 | 4 | 32 | 16 | 1 | 8 | 2 | 64 | 32 | 0.75 | 8 | 2 | 256 | 128 | 0.75 | 8 | 8 | 2 | 2 | 2 | 8 | 1 | 2 | 0.25 | 0.25 | 8 | 4 | 32 | 16 | 1 | 8 | 8 | 32 | 32 | 2 | 8 | 0.25 | 64 | 4 | 0.09 | 8 | 0.5 | 2 | 0.25 | 0.19 |
| M. peregrinum ATCC 700686 | 16 | 8 | 0.5 | 0.25 | 1 | 16 | 4 | 1 | 0.25 | 0.5 | 16 | 4 | 16 | 2 | 0.38 | 8 | 8 | 256 | 256 | 2 | 16 | 8 | 1 | 0.5 | 1 | 8 | 1 | 0.5 | 0.25 | 0.63 | 8 | 4 | 8 | 4 | 1 | 8 | 8 | <0.25 | <0.25 | 2 | 8 | 1 | 4 | 0.25 | 0.19 | 8 | 4 | 0.12 | 0.06 | 1 |
| M. chelonae ATCC 35752 | 16 | 16 | 0.25 | 0.25 | 2 | 8 | 2 | 64 | 16 | 0.5 | 16 | 16 | >256 | >256 | 2 | 16 | 16 | 256 | 256 | 2 | 16 | 16 | 2 | 2 | 2 | 16 | 4 | 32 | 4 | 0.38 | 8 | 8 | 2 | 2 | 2 | 16 | 8 | 0.5 | 0.25 | 1 | 16 | 1 | 4 | 0.5 | 0.19 | 16 | 2 | 0.5 | 0.015 | 0.16 |
| M. chelonae (clinical) | 32 | 32 | 1 | 2 | 3 | 32 | 4 | 64 | 16 | 0.38 | 32 | 32 | >256 | >256 | 2 | 32 | 32 | 256 | 256 | 2 | 32 | 32 | 1 | 1 | 2 | 32 | 4 | 1 | 0.25 | 0.38 | 32 | 32 | 32 | 32 | 2 | 32 | 32 | 16 | 16 | 2 | 32 | 8 | 32 | 8 | 0.5 | 32 | 8 | 0.5 | 0.12 | 0.49 |
a
A, MIC of rifabutin (drug A) tested alone; a, MIC of rifabutin (drug A) tested with the second drug in the combination (drug B); B, MIC of the standard antimycobacterial drug B tested alone; b, MIC of the standard antimycobacterial drug B tested in combination with rifabutin; FICI, fractional inhibitory concentration index. FICIs of ≤0.5, indicating synergism, are in boldface.