TABLE 1.
In vitro inhibitory activities of amikacin, isepamicin, kanamycin, tobramycin, gentamicin, streptomycin, and capreomycin against 117 isolates of M. abscessus, 48 isolates of M. fortuitum, and 20 isolates of M. chelonae
| Bacterium and antimicrobial agent | MIC (μg/ml)
|
% (no.) of isolates with indicated MICa (μg/ml)
|
||||
|---|---|---|---|---|---|---|
| Range | 50% | 90% | ≤16 | 32 | ≥64 | |
| M. abscessus (n = 117) | ||||||
| Amikacin | 4->128 | 16 | 32 | 87.2 (102) | 10.3 (12) | 2.6 (3) |
| Isepamicin | 2->128 | 8 | 16 | 95.7 (112) | 2.6 (3) | 1.7 (2) |
| Kanamycin | 1->128 | 8 | 8 | 98.3 (115) | 0 (0) | 1.7 (2) |
| Tobramycin | 4->128 | 8 | 16 | 94.9 (111) | 3.4 (4) | 1.7 (2) |
| Gentamicin | 8->128 | 32 | 64 | 10.3 (12) | 69.2 (81) | 20.5 (24) |
| Streptomycin | 4->128 | 128 | >128 | 1.7 (2) | 11.1 (13) | 87.2 (102) |
| Capreomycin | 64->128 | 128 | >128 | 0 (0) | 0 (0) | 100 (117) |
| M. fortuitum (n = 48) | ||||||
| Amikiacin | 0.5-4 | 1 | 4 | 100 (48) | 0 (48) | 0 (48) |
| Isepamicin | 2-64 | 8 | 16 | 93.8 (45) | 4.2 (2) | 2.1 (1) |
| Kanamycin | 2->128 | 8 | 32 | 89.6 (43) | 6.3 (3) | 4.2 (2) |
| Tobramycin | 2-128 | 16 | 64 | 52.1 (25) | 29.2 (14) | 18.8 (9) |
| Gentamicin | 1-32 | 16 | 32 | 64.6 (31) | 35.4 (17) | 0 (0) |
| Streptomycin | 16->128 | 64 | 128 | 4.2 (2) | 14.6 (7) | 81.3 (39) |
| Capreomycin | 1-128 | 8 | 32 | 81.3 (39) | 12.5 (6) | 6.3 (3) |
| M. chelonae (n = 20) | ||||||
| Amikacin | 4-16 | 8 | 8 | 100 (20) | 0 (0) | 0 (0) |
| Isepamicin | 4-8 | 4 | 8 | 100 (20) | 0 (0) | 0 (0) |
| Kanamycin | 2-64 | 4 | 8 | 90 (18) | 5 (1) | 5 (1) |
| Tobramycin | 4-128 | 16 | 32 | 80 (16) | 15 (3) | 5 (1) |
| Gentamicin | 16-64 | 16 | 32 | 60 (12) | 58.3 (7) | 5 (1) |
| Streptomycin | 32-128 | 64 | 128 | 0 (0) | 15 (3) | 85 (17) |
| Capreomycin | 32->128 | 128 | 128 | 0 (0) | 5 (1) | 95 (19) |
a
RGM isolates with amikacin MICs of ≤16, 32, and ≥ 64 μg/ml were within the susceptible, intermediate, and resistant ranges for amikacin, respectively, according to the CLSI guidelines.