TABLE 4.
In vitro activities of plazomicin and comparators against MDR Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa
| Organism (no. of isolates) and agent | MIC (µg/ml) |
% of isolates |
||||
|---|---|---|---|---|---|---|
| 50% | 90% | Range | Susceptible | Intermediate | Resistant | |
| MDR Escherichia coli (358)a | ||||||
| Plazomicin | 0.5 | 1 | ≤0.12 to >64 | 99.4 | 0.3 | 0.3 |
| Amikacin | 4 | 8 | ≤1 to >64 | 98.0 | 1.2 | 0.8 |
| Gentamicin | 1 | >32 | ≤0.5 to >32 | 52.8 | 2.2 | 45.0 |
| Tobramycin | 8 | 32 | ≤0.5 to >64 | 42.5 | 14.2 | 43.3 |
| Cefazolin | >128 | >128 | ≤0.5 to >128 | 6.4 | 7.0 | 86.6 |
| Ceftazidime | 8 | >32 | ≤0.25 to >32 | 46.1 | 8.4 | 45.5 |
| Ceftriaxone | 64 | >64 | ≤0.25 to >64 | 22.1 | 1.1 | 76.8 |
| Ciprofloxacin | >16 | >16 | ≤0.06 to >16 | 4.2 | 0 | 95.8 |
| Ertapenem | ≤0.03 | 0.12 | ≤0.03 to >32 | 97.2 | 1.4 | 1.4 |
| Meropenem | ≤0.03 | 0.06 | ≤0.03 to 32 | 99.7 | 0 | 0.3 |
| Piperacillin-tazobactam | 4 | 64 | ≤1 to >512 | 86.3 | 5.9 | 7.8 |
| Tigecycline | 0.25 | 1 | 0.12 to 4 | 99.7 | 0.3 | 0 |
| Trimethoprim-sulfamethoxazole | >8 | >8 | ≤0.12 to >8 | 14.2 | NAc | 85.8 |
| MDR Klebsiella pneumoniae (74)a | ||||||
| Plazomicin | 0.25 | 0.5 | ≤0.12 to >64 | 97.3 | 1.3 | 1.4 |
| Amikacin | 2 | 8 | ≤1 to >64 | 98.6 | 0 | 1.4 |
| Gentamicin | 32 | >32 | ≤0.5 to >32 | 45.9 | 0 | 54.1 |
| Tobramycin | 8 | 32 | ≤0.5 to >64 | 31.1 | 28.4 | 40.5 |
| Cefazolin | >128 | >128 | 2 to >128 | 2.7 | 2.7 | 94.6 |
| Ceftazidime | 32 | >32 | ≤0.25 to >32 | 24.3 | 6.8 | 68.9 |
| Ceftriaxone | >64 | >64 | ≤0.25 to >64 | 6.8 | 0 | 93.2 |
| Ciprofloxacin | 16 | >16 | ≤0.06 to >16 | 14.9 | 9.4 | 75.7 |
| Ertapenem | 0.12 | 8 | ≤0.03 to >32 | 81.1 | 5.4 | 13.5 |
| Meropenem | ≤0.03 | 1 | ≤0.03 to 16 | 91.9 | 2.7 | 5.4 |
| Piperacillin-tazobactam | 16 | >512 | 2 to >512 | 63.5 | 13.5 | 23.0 |
| Tigecycline | 1 | 4 | 0.5 to 4 | 87.8 | 12.2 | 0 |
| Trimethoprim-sulfamethoxazole | >8 | >8 | 0.25 to >8 | 2.7 | NA | 97.3 |
| MDR Pseudomonas aeruginosa (256)b | ||||||
| Plazomicin | 8 | 64 | ≤0.12 to >64 | NA | NA | NA |
| Amikacin | 8 | 64 | ≤1 to >64 | 80.5 | 6.2 | 13.3 |
| Gentamicin | 4 | >32 | ≤0.5 to >32 | 61.7 | 9.4 | 28.9 |
| Tobramycin | 1 | 64 | ≤0.5 to >64 | 72.3 | 4.7 | 23.0 |
| Ceftazidime | 32 | >32 | 2 to >32 | 16.8 | 24.2 | 59.0 |
| Ciprofloxacin | 2 | >16 | ≤0.06 to >16 | 30.9 | 21.4 | 47.7 |
| Meropenem | 8 | 32 | 0.25 to >32 | 15.2 | 21.5 | 63.3 |
| Piperacillin-tazobactam | 64 | 512 | ≤1 to >512 | 20.7 | 36.3 | 43.0 |
MDR Enterobacteriaceae were defined as isolates nonsusceptible to ≥1 antimicrobial agent in ≥3 of the following antimicrobial agent categories: aminoglycosides (amikacin, gentamicin, tobramycin), antipseudomonal penicillins and β-lactamase inhibitors (piperacillin-tazobactam), carbapenems (ertapenem, meropenem), extended-spectrum cephalosporins (ceftazidime, ceftriaxone), fluoroquinolones (ciprofloxacin), folate pathway inhibitors (trimethoprim-sulfamethoxazole), and glycylcyclines (tigecycline).
MDR Pseudomonas aeruginosa isolates were defined as isolates nonsusceptible to ≥1 antimicrobial agent in ≥3 of the following antimicrobial agent categories: aminoglycosides (amikacin, gentamicin, tobramycin), antipseudomonal penicillins and β-lactamase inhibitors (piperacillin-tazobactam), antipseudomonal carbapenems (meropenem), antipseudomonal cephalosporins (ceftazidime), and fluoroquinolones (ciprofloxacin).
NA, MIC breakpoint not applicable.