Table 1.
Activity and frequency of individual and cross-resistance resistance development for the different antipseudomonals, according to mechanisms implicated
| Antimicrobiala | PIP-TZ | CAZ | FEP | TOL-TZ | ATM | IMP | MER | FQ | AMG | COL | FOS | MIC(mg/L) | MPC(mg/L) | Primary R MEC | Secondary R MEC |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PIP/TZ | +++ | +++ | ++ | - | ++ | - | + | -/+ | - | - | - | 2 | >32 | ↑ AmpC | ↑ MexAB |
| CAZ | +++ | +++ | ++ | -/+ | ++ | - | + | -/+ | - | - | - | 1 | >32 | ↑ AmpC | ↑ MexAB |
| FEP | ++ | ++ | +++ | -/+ | +++ | - | ++ | + | + | - | - | 1 | >32 | ↑ MexAB/XY | ↑ AmpC |
| TOL/TZ | -/+ | + | + | + | -/+ | - | -/+ | - | - | - | - | 0.5 | 2 | ↑ AmpC+mut AmpC | PBP3 |
| ATM | ++ | ++ | +++ | -/+ | +++ | - | ++ | + | - | - | - | 4 | >32 | ↑ MexAB/XY | ↑ AmpC |
| IMP | -/+ | -/+ | -/+ | - | -/+ | +++ | ++ | -/+ | - | - | - | 1 | >32 | OprD | MexST (↑ MexEF ↓ OprD) |
| MER | + | + | + | - | + | ++ | ++ | + | - | - | - | 0.5 | 8 | OprD | ↑ MexAB, PBP3 |
| FQb | + | + | ++ | - | ++ | -/+ | + | +++ | + | - | - | 0.12 | 2 | QRDR | ↑ MexAB/XY/CD/EF |
| AMGc | - | - | + | - | - | - | - | + | ++ | - | - | 1 | 8 | ↑ MexXY | FusA |
| COL | - | - | -/+ | - | - | -/+ | -/+ | -/+ | + | - | 0.5 | 2 | pmrAB/phoPQ | parRS | |
| FOS | - | - | - | - | - | - | - | - | - | - | ++++ | 64 | >1,024 | GlpT |
PIP-TZ: piperacillin-tazobactam; CAZ: ceftazidime; FEP: cefepime; TOL-TZ: ceftolozane-tazobactam; ATM: aztreonam; IMP: imipenem; MER: meropenem; FQ: Fluoroquinolones; AMG: aminoglycosides; COL: colistin; FOS: fosfomycin. MIC: minimum inhibitory concentration. MPC: mutant prevention concentration (concentration preventing selection of resistant mutants). R MEC: resistance mechanism
Frequency of spontaneous development of clinical resistance (EUCAST resistance breakpoints) to antibiotics in columns by exposure to antibiotics in rows. (++++) Extremely elevated resistance development, (+++) Very elevated resistance development, (++) Elevated resistance development, (+) Moderate resistance development, (-/+) Low or improbable resistance development, (-) Non expected resistance development. Data shown in the Table refer to wild-type strains without acquired mechanisms of resistance, using as reference strain PAO1 (28;236; A. Oliver data non published).
FQ resistance development: levofloxacin > ciprofloxacin (pumps hyperexpression). Data shown in the Table refer to ciprofloxacin.
Resistance development aminoglycosides: gentamicin > amikacin > tobramycin. Data shown in the Table refer to tobramycin.