Table 1. Results of antimicrobial susceptibility and carbapenemase producer tests on Escherichia coli isolate.
| Antimicrobial susceptibility test | Carbapenemase producer tests | |||
|---|---|---|---|---|
| Antimicrobials | MIC (µg/mL) | Results* | Methods | Results |
| Doripenem | >2 | R | MHT | Weak positive |
| Imipenem | >8 | R | CIT | PBA: Negative |
| Meropenem | >8 | R | EDTA: Positive | |
| Ampicillin/Sulbactam | > 16/8 | R | XpertCarba-R | blaNDM detected |
| Ticarcillin/Clavulanate | > 64 | R | blaOXA-48-like detected | |
| Piperacillin/Tazobactam | > 64 | R | REBA-EAC assay | Gram negative: E. coli |
| Piperacillin | > 64 | R | ESBL: blaCTX-M-1 | |
| Ampicillin | > 16 | R | AmpC β-lactamase: blaACT, blaCMY | |
| Cefazolin | >4 | R | Carbapenemase: blaNDM, blaOXA-48-like | |
| Cefuroxime | > 16 | R | Sequence analysis | NDM: blaNDM-5 |
| Cefoxitin | > 16 | R | OXA-48: blaOXA-48-like | |
| Cefotaxime | > 32 | R | ||
| Ceftazidime | > 16 | R | ||
| Cefepime | > 16 | R | ||
| Aztreonam | > 16 | R | ||
| Ciprofloxacin | >2 | R | ||
| Levofloxacin | >4 | R | ||
| Trimethoprim/Sulfamethoxazole | > 2/38 | R | ||
| Gentamicin | >8 | R | ||
| Tobramycin | >8 | R | ||
| Amikacin | ≤ 16 | S | ||
| Tigecycline | ≤2 | S | ||
| Colistin | ≤2 | S | ||
| ESBL phenotypic confirmatory test | N | |||
*Interpretative criteria of susceptibilities recommended by the Clinical and Laboratory Standards Institute guidelines [10].
Abbreviations: MIC, minimal inhibitory concentration; R, resistant; S, susceptible; N, negative; MHT, modified Hodge test; CIT, carbapenemase inhibition test; PBA, phenylboronic acid; EDTA, ethylenediaminetetraacetic acid; REBA-EAC, reverse blot hybridization assay for detection of extended-spectrum β-lactamases, AmpC β-lactamases, and carbapenemases; ESBL, extended spectrum β-lactamase.