TABLE IV. Mechanisms of carbapenem resistance and antimicrobial resistance among clinical Pseudomonas aeruginosa isolates from infection.
| Mechanisms of resistance: efflux system, AmpC, oprD mutation* (number of isolates) | Antimicrobial resistance profile** (number of isolates) | MIC*** (μg/mL) | |
|---|---|---|---|
|
| |||
| IPM | MER | ||
| +,+,+ (3) | IPM MEM FEP CIP CAZ TZP TOB GEN (1) | 32 | 32 |
| IPM MEM (1) | 24 | 12 | |
| IPM (1) | 12 | 4 | |
| +,-,+ (3) | IPM MEM AMK FEP CIP CAZ TZP TOB GEN (1) | 24 | > 32 |
| IPM MEM FEP CIP CAZ TZP TOB GEN (1) | 16 | > 32 | |
| IPM (1) | 6 | 1.5 | |
| -,+,+ (3) | IPM MEM FEP CIP CAZ TZP TOB GEN (2) | 24 | > 32 |
| 32 | > 32 | ||
| IPM (1) | 16 | 2 | |
| -,-,+ (1) | IPM MEM FEP CIP CAZ TZP TOB GEN (1) | 4 | 6 |
| +,+,-(1) | Susceptible (1) | 1.5 | 0.38 |
| -,+,- (3) | Susceptible (3) | 1.5-0.75 | 0.19-0.38 |
| -,-,- (21) | AMK FEP CIP CAZ TZP TOB GEN (2) | 0.75-1.5 | 0.094-2 |
| AMK FEP CIP CAZ TOB GEN (2) | 0.75 | 1 | |
| AMK FEP CAZ PIP (1) | 0.75 | 0.19 | |
| TOB, GEN (1) | 1 | 0.25 | |
| Susceptible (15) | 0.5-1 | 0.064-0.5 | |
*: assessed by comparison of carbapenem minimum inhibitory concentration (MIC) and in combination with PAβN or cloxacillin and sequencing of oprD. Antimicrobial susceptibility was determined by disc diffusion (**) or E-test (***); + or - : presence or absence of mechanism of resistance, respectively; AMK: amikacin; CAZ: ceftazidime; CIP: ciprofloxacin; FEP: cefepime; GEN: gentamicin; IPM: imipenem; MEM: meropenem; TZP: piperacillin-tazobactam; TOB: tobramycin; IMP and MER MIC interpretation: ≤ 2, susceptible; 4, intermediate; ≥ 8, resistant.