TABLE 3.
In vitro activities of various antimicrobial agents against epidemic and sporadic A. baumannii isolates
| A. baumannii group (no. of strains tested) | Antibiotic | MIC (mg/liter)a
|
% Susceptible | |||
|---|---|---|---|---|---|---|
| Range | 50% | 90% | Geometric mean | |||
| Outbreak isolates (16) | Gentamicin | 1–>8 | >8 | >8 | 12.1 | 25 |
| Amikacin | 2–>32 | 8 | >32 | 27.6 | 63 | |
| Amoxicillin-clavulanate | 4/2–>32/2 | 32/2 | >32/2 | 37.5 | 25 | |
| Mezlocillin | 8–>32 | >32 | >32 | 45.5 | 31 | |
| Piperacillin-tazobactam | ≤1/4–32/4 | 4/4 | 16/4 | 7.0 | 94 | |
| Meropenem | ≤0.25–4 | 1 | 2 | 0.96 | 100 | |
| Imipenem | ≤0.25–1 | ≤0.25 | 0.5 | 0.25 | 100 | |
| Cefuroxime | 16–>32 | 32 | >32 | 41.0 | 0 | |
| Cefepime | 2–64 | 8 | 16 | 11.8 | 81 | |
| Ceftriaxone | 4–>32 | 16 | >32 | 33.5 | 44 | |
| Cefotaxime | 4–>16 | 16 | >16 | 18.7 | 44 | |
| Ciprofloxacin | 0.5–>8 | 8 | >8 | 10.6 | 13 | |
| Sporadic isolates (18) | Gentamicin | 0.5–>8 | 1 | >8 | 5.0 | 67 |
| Amikacin | 1–16 | 4 | 8 | 3.6 | 100 | |
| Amoxicillin-clavulanate | ≤0.25/2–>32/2 | 4/2 | >32/2 | 12.8 | 61 | |
| Mezlocillin | 8–>32 | 16 | >32 | 23.6 | 61 | |
| Piperacillin-tazobactam | ≤1/4–32/4 | ≤1/4 | 16/4 | 5.3 | 100 | |
| Meropenem | ≤0.25–1 | 0.5 | 1 | 0.51 | 100 | |
| Imipenem | ≤0.25–0.5 | ≤0.25 | ≤0.25 | 0.14 | 100 | |
| Cefuroxime | 16–>32 | 32 | >32 | 36.4 | 0 | |
| Cefepime | 1–8 | 2 | 8 | 3.3 | 100 | |
| Ceftriaxone | 4–>32 | 8 | 16 | 11.8 | 63 | |
| Cefotaxime | 4–>16 | 8 | >16 | 11.8 | 63 | |
| Ciprofloxacin | 0.5–4 | 0.5 | 4 | 1.3 | 100 | |
a
50% and 90%, MICs at which 50 and 90% of the isolates are inhibited. Values separated with a shill apply to the first- and second-listed antibiotics of the compound, respectively.