TABLE 3.
Comparison of ranges, MIC50s, MIC90s, and percentage of isolates susceptible/intermediate to imipenem, meropenem, and ertapenem for Nocardia isolates by broth microdilution
| Complex or species and drug | Intermediate breakpoint (μg/ml) | No. of isolates tested | MIC (μg/ml) |
% susceptible/intermediate | ||
|---|---|---|---|---|---|---|
| Range | 50% | 90% | ||||
| N. cyriacigeorgica | ||||||
| Imipenem | 8 | 25 | ≤1–32 | 8 | >16 | 60 |
| Meropenem | 8 | 25 | 4–>16 | 8 | >16 | 68 |
| Ertapenem | 4a | 26 | 2–>16 | 8 | >16 | 15 |
| N. nova complex | ||||||
| Imipenem | 8 | 57 | ≤0.5–8 | ≤1 | 2 | 100 |
| Meropenem | 8 | 54 | ≤0.5–16 | ≤1 | 4 | 94 |
| Ertapenem | 4a | 57 | 0.5–16 | 2 | 4 | 96 |
| N. abscessus | ||||||
| Imipenem | 8 | 13 | 2–32 | >16 | 32 | 23 |
| Meropenem | 8 | 11 | 1–8 | 2 | 4 | 100 |
| Ertapenem | 4a | 13 | 0.5–4 | 2 | 4 | 100 |
| N. brasiliensis | ||||||
| Imipenem | 8 | 23 | 16–>32 | >16 | >32 | 0 |
| Meropenem | 8 | 23 | 4–>16 | >16 | >16 | 48 |
| Ertapenem | 4a | 23 | 4–>16 | >16 | >16 | 26 |
| N. farcinica | ||||||
| Imipenem | 8 | 19 | ≤1–>16 | 8 | >16 | 63 |
| Meropenem | 8 | 18 | 4–>16 | 8 | >16 | 33 |
| Ertapenem | 4a | 19 | 4–>16 | 8 | 16 | 21 |
| N. transvalensis complex | ||||||
| Imipenem | 8 | 18 | 4–>32 | 16 | >32 | 22 |
| Meropenem | 8 | 18 | 2–16 | 8 | 16 | 83 |
| Ertapenem | 4a | 18 | 2–>16 | >16 | >16 | 22 |
a
Based on the CLSI breakpoint for bacteria (8).