Table 3. MICs of antibiotics against K. pneumoniae NVT2001S and its porin-loss mutants with extended-spectrum β-lactamase.
| Antibiotica |
Minimal inhibitory concentration (μg/ml)b
|
|||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
NVT2001S
|
ΔompK35
|
ΔompK36
|
ΔompK35/36
|
|||||||||||||
|
CTX-M-15c
|
SHV-12
|
CTX-M-15
|
SHV-12
|
CTX-M-15
|
SHV-12
|
CTX-M-15
|
SHV-12
|
|||||||||
| pCTd | LCP | pSH | LCP | pCT | LCP | pSH | LCP | pCT | LCP | pSH | LCP | pCT | LCP | pSH | LCP | |
| Aztreonam | 64 | 128 | ≥256 | 128 | ≥256 | ≥256 | ≥256 | ≥256 | 128 | ≥256 | ≥256 | ≥256 | ≥256 | ≥256 | ≥256 | ≥256 |
| Ampicillin | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 |
| Piperacillin/TZB | 16 | ≤4 | ≥128 | 8 | 16 | 16 | ≥128 | ≥128 | ≥128 | ≥128 | ≥128 | ≥128 | ≥128 | ≥128 | ≥128 | ≥128 |
| Cefazolin | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 |
| Cephalothin | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 | ≥32 |
| Cefoxitin | ≤4 | ≤4 | ≤4 | ≤4 | ≤4 | ≤4 | ≤4 | ≤4 | 16 | 32 | 32 | 16 | 64 | 32 | 32 | 32 |
| Ceftriaxone | ≥256 | ≥256 | 128 | 16 | ≥256 | ≥256 | 128 | 32 | ≥256 | ≥256 | ≥256 | 64 | ≥256 | ≥256 | ≥256 | ≥256 |
| Cefpodoxime | ≥64 | ≥64 | ≥64 | 32 | ≥64 | ≥64 | ≥64 | 32 | ≥64 | ≥64 | ≥64 | ≥64 | ≥64 | ≥64 | ≥64 | ≥64 |
| Cefotaxime | ≥128 | ≥128 | 32 | 16 | ≥128 | ≥128 | 32 | 16 | ≥128 | ≥128 | ≥128 | 64 | ≥128 | ≥128 | ≥128 | ≥128 |
| Cefotaxime/CLA | ≤0.12 | ≤0.12 | ≤0.12 | ≤0.12 | ≤0.12 | ≤0.12 | ≤0.12 | ≤0.12 | 0.25 | 0.5 | ≤0.12 | ≤0.12 | 2 | 4 | 0.5 | 0.5 |
| Ceftazidime | 16 | 64 | ≥256 | 128 | 32 | 128 | ≥256 | ≥256 | 32 | 128 | ≥256 | ≥256 | 128 | ≥256 | ≥256 | ≥256 |
| Ceftazidime/CLA | 0.25 | 0.5 | 0.5 | 0.25 | 0.25 | 1 | 1 | 0.5 | 0.25 | 1 | 2 | 0.5 | 1 | 4 | 8 | 8 |
| Cefepime | 16 | ≥32 | 8 | 2 | ≥32 | ≥32 | 8 | 2 | ≥32 | ≥32 | ≥32 | 16 | ≥32 | ≥32 | ≥32 | ≥32 |
| Ciprofloxacin | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 | ≤1 |
| Gentamicin | ≥32 | ≤4 | ≤4 | ≤4 | ≥32 | ≤4 | ≤4 | ≤4 | ≥32 | ≤4 | ≤4 | ≤4 | ≥32 | ≤4 | ≤4 | ≤4 |
aTZB, tazobactam with a fixed concentration of 4 μg/ml; CLA, clavulanic acid with a fixed concentration of 4 μg/ml.
bBoldface numbers indicate a significant (≥4-fold) difference in the MICs of K. pneumoniae NVT2001S and its derived strains, while the underlined numbers were above the breakpoint of susceptibility established by CLSI in 2013 [14].
cThe β-lactamase on the plasmid was shown, and the plasmid was transferred into K. pneumoniae NVT2001S and its porin-loss mutants.
dpCT and pSH, plasmids from clinical isolates; LCP, low-copy-number plasmid.