Table. Minimum inhibitory concentrations (MIC) range, MIC50, MIC90 of cefiderocol-resistant NDM-producing Klebsiella pneumoniae isolates from a tertiary care hospital outbreak in Florence, Italy, August 2021–June 2022 (n = 21).
| Antibiotics | AMC | AZAa | CAZ | CAA | CEP | CRO | CTA | ERT | MEM | PTZ | AMK | GNT | CIP | LEV | CLS | FOS | T/S | TIGb |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MIC range (mg/L) | > 64 | 0.125 to 0.5 | > 64 | 32 to > 64 | > 16 | > 4 | > 64 | 2 to > 2 | 32 to > 64 | 64 to > 128 | 16 to > 16 | > 8 | > 1 | > 8 | ≤ 0.5 to 1 | 4 to > 128 | > 8/152 | ≤ 0.25 to 0.5 |
| MIC50 (mg/L) | > 64 | 0.25 | > 64 | > 64 | > 16 | > 4 | > 64 | > 2 | 32 | > 128 | > 16 | > 8 | > 1 | > 8 | ≤ 0.5 | 16 | > 8/152 | ≤ 0.25 |
| MIC90 (mg/L) | > 64 | 0.25 | > 64 | > 64 | > 16 | > 4 | > 64 | > 2 | > 64 | > 128 | > 16 | > 8 | > 1 | > 8 | 1 | > 128 | > 8/152 | 0.5 |
| S | 0 | 21 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 21 | 12 | 0 | 21 |
AMC: amoxicillin-clavulanic acid; AMK: amikacin; AZA: aztreonam-avibactam; CAA: ceftazidime/avibactam; CAZ: ceftazidime; CEP: cefepime; CIP: ciprofloxacin; CRO: ceftriaxone; CST: colistin; CTA: ceftolozane-tazobactam; ERT: ertapenem; FOS: fosfomycin; GNT: gentamicin; LEV: levofloxacin; MEM: meropenem; MIC: minimum inhibitory concentration; S: number of susceptible isolates; PTZ: piperacillin-tazobactam; T/S: trimethoprim-sulfamethoxazole; TGC: tigecycline.
a Interpreted according to aztreonam clinical breakpoints [16].
b Interpreted according to pharmacokinetics/pharmacodynamics (PK/PD) EUCAST clinical breakpoints [16].
MICs were obtained using reference broth microdilution or agar dilution for fosfomycin [15].