Table 1.
Phenotypic characteristics of the pandrug-resistant K. pneumoniae
| Method | Antimicrobial | MIC (mg/L) | Interpretationa | |
|---|---|---|---|---|
| Single susceptibility testing | ||||
| Vitek-2® | ||||
| amoxicillin/clavulanic acid | ≥32 | resistant | ||
| cefotaxime | ≥64 | resistant | ||
| ceftazidime | ≥64 | resistant | ||
| cefoxitin | ≥64 | resistant | ||
| ciprofloxacin | ≥4 | resistant | ||
| trimethoprim/ sulfamethoxazole | ≥320 | resistant | ||
| gentamicin | ≥16 | resistant | ||
| imipenem | ≥16 | resistant | ||
| meropenem | ≥16 | resistant | ||
| nitrofurantoin | 256 | resistant | ||
| piperacillin/tazobactam | ≥128 | resistant | ||
| tobramycin | ≥16 | resistant | ||
| Gradient test | ||||
| amikacin | >256 | resistant | ||
| aztreonam | >256 | resistant | ||
| ceftazidime/avibactam | >256 | resistant | ||
| ceftolozane/tazobactam | >256 | resistant | ||
| doripenem | >32 | resistant | ||
| eravacycline | 4 | resistant | ||
| fosfomycin | >256 | resistant | ||
| imipenem | >32 | resistant | ||
| meropenem | >32 | resistant | ||
| plazomicin | >256 | unknown | ||
| sulbactam | >256 | unknown | ||
| tigecycline | 6 | resistant | ||
| Broth microdilution | ||||
| colistin | 16 | resistant | ||
|
| ||||
|
MIC mg/L |
||||
| Antimicrobial | single | combined with aztreonam | Interpretationb | |
|
| ||||
| Gradient test superposition | ||||
| amoxicillin/clavulanic acid | >256 | 12 | synergy | |
| ceftazidime/avibactam | >256 | 0.5 | synergy | |
| ceftolozane/tazobactam | >256 | 48 | synergy | |
| colistin | 8 | 12 | no synergy | |
| meropenem | >32 | 16 | synergy | |
| piperacillin/tazobactam | >256 | 32 | synergy | |
a
According to EUCAST (www.eucast.org).
b
Synergy was defined as the occurrence of an inhibition zone when an antimicrobial was combined with aztreonam.