Table 1.
Susceptibility testing results of serial ST410 E. coli isolates
| Antimicrobials | MICs (mg/L) | ||
|---|---|---|---|
| E. coli EC1 (Baseline) |
E. coli EC2 (Day 14) |
E. coli EC3 (Day 65) |
|
| Aztreonam (ATM) | 2 (S) | 4 (S) | 32 (R) |
| Piperacillin/tazobactam (TZP) | ≥128 (R) | ≥128 (R) | ≥128 (R) |
| Cefotaxime (CTX) | 4 (R) | 8 (R) | ≥64 (R) |
| Ceftriaxone (CRO) | 4 (R) | 8 (R) | ≥64 (R) |
| Ceftazidime (CAZ) | 4 (S) | 4 (S) | ≥64 (R) |
| Ceftazidime/avibactam (CZA) | 0.75 (S)b | 1.5 (S)b | >256 (R)b |
| Cefepime (FEP) | ≤1 (S) | 8 (SDD) | 16 (R) |
| Ertapenem (ETP) | ≤0.5 (S) | 4 (R) | 0.5 (S)a |
| Imipenem (IMI) | ≤0.25 (S) | 2 (I)a | 2 (I)a |
| Meropenem (MEM) | ≤0.25 (S) | 2 (I)a | 1 (S) |
| Cefiderocol (FDC)c | 0.5 (S) | 0.25 (S) | 8 (R) |
All testing was performed using Vitek2 unless otherwise indicated. R, resistant; S, susceptible; SDD, susceptible dose dependent.
Testing completed with Etest (bioMérieux).
Testing completed with gradient diffusion strip (Liofilchem).
Testing completed with the iron-depleted broth microdilution protocol (see Methods).