Table 1.
MICs, sequence type, CMY variant and number of passages with cefepime of E. coli Ec-1, and its cefepime-resistant derivatives.
| Ec-1 | Ec-2 | EC-4 | EC-16 | EC-32 | ||
|---|---|---|---|---|---|---|
| Antibiotic MIC, mg/L (interpretation)a | Cefepimec | 0.125 (S) | 48 (R) | 4 (I) | 32 (R) | 256 (R) |
| Ampicillin | ≥32 (R) | ≥32 (R) | ≥32 (R) | ≥32 (R) | ≥32 (R) | |
| Piperacillin-tazobactam | ≤4 (S) | 8 (S) | 8 (S) | 64 (R) | 64 (R) | |
| Ticarcillin-clavulanate | ≤8 (S) | ≥256 (R) | ≥256 (R) | ≥256 (R) | ≥256 (R) | |
| Cephalothinb | ≥32 (R) | ≥32 (R) | ≥32 (R) | ≥32 (R) | ≥32 (R) | |
| Cefoxitinb | 64 (R) | ≥128 (R) | ≥128 (R) | ≥128 (R) | ≥128 (R) | |
| Cefotaxime | 4 (R) | 64 (R) | 64 (R) | ≥128 (R) | ≥128 (R) | |
| Cefotaxime-clavulanate | 4 (NA) | 32 (NA) | 32 (NA) | 64 (NA) | 64 (NA) | |
| Ceftriaxone | 8 (R) | 128 (R) | 128 (R) | ≥256 (R) | ≥256 (R) | |
| Ceftazidime | 16 (R) | ≥256 (R) | ≥256 (R) | ≥256 (R) | ≥256 (R) | |
| Ertapenem | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | |
| Imipenem | ≤0.5 (S) | ≤0.5 (S) | ≤0.5 (S) | ≤0.5 (S) | ≤0.5 (S) | |
| Meropenem | ≤1 (S) | ≤1 (S) | ≤1 (S) | ≤1 (S) | ≤1 (S) | |
| Ciprofloxacin | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | |
| Amikacin | ≤4 (S) | ≤4 (S) | ≤4 (S) | ≤4 (S) | ≤4 (S) | |
| Gentamicin | ≤1 (S) | ≤1 (S) | ≤1 (S) | ≤1 (S) | ≤1 (S) | |
| Colistin | ≤0. 25 (S) | ≤0. 25 (S) | ≤0. 25 (S) | ≤0. 25 (S) | ≤0. 25 (S) | |
| Polymyxin Bb | ≤0. 25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0. 25 (S) | ≤0.25 (S) | |
| Tigecycline | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | ≤0.25 (S) | |
| Aztreonam | 4 (I) | ≥32 (R) | ≥32 (R) | ≥32 (R) | ≥32 (R) | |
| Co-trimoxazole | ≤0.5 (S) | ≤0.5 (S) | ≤0.5 (S) | ≤0.5 (S) | ≤0.5 (S) | |
| Sequence type (ST)d | ST131 | ST131 | ST131 | ST131 | ST131 | |
| CMY variant | 2 | 33 | 69 | 69 | 69 | |
| Passages with cefepime (at of MIC) | – | – | 24 | 27 | 30 |
aAccording to the EUCAST criteria (v6.0, 2016). MIC values (besides for cefepime) were obtained implementing the GNX2F, and ESB1F plates (Trek diagnostics). bAccording to CLSI criteria (M100-S26, 2016). cMIC was obtained using Etest®. dThe ST type was determined with the MLST 1.8 tool available on the Center for Genomic Epidemiology online platform.