Table 1.
Antibiotic resistance in K. pneumoniae SA-KpST14.
| Antimicrobial category | Antimicrobial agents | MIC (μg/ml) VITEK II | Interpretation (CLSI breakpoints) | Genes associated with resistance |
|---|---|---|---|---|
| β-lactams | Ampicillin | ≥ 32 | R | blaOXA-1, blaSHV-28, blaNDM-1, blaOXA-48, blaCTX-M-14b |
| Amoxicillin/Clavulanic acid | ≥ 32 | R | ||
| Piperacillin/Tazobactam | ≥ 128 | R | ||
| Ceftazidime/Avibactam | > 256* | R | ||
| Cefoxitin | ≥ 64 | R | ||
| Ceftazidime | ≥ 64 | R | ||
| Cefepime | ≥ 64 | R | ||
| Cefalotin | ≥ 64 | R | ||
| Ceftriaxone | ≥ 64 | R | ||
| Imipenem | > 32* | R | ||
| Meropenem | ≥ 16 | R | ||
| Aztreonam | > 256* | R | ||
| Fluoroquinolones | Ciprofloxacin | ≥ 4 | R | aac(6′)-Ib-cr, gyrA (S83Y, D87G). parC (S80I) |
| Aminoglycosides | Amikacin | ≥ 64 | R | aac(6′)-Ib-cr, aph(3′)-Ib, aph(6)-Id, dfrA12, armA, aadA2, strAB, aph(3′)-VI |
| Gentamicin | ≥ 16 | R | ||
|
Trimethoprim/ Sulfamethoxazole |
Trimethoprim/ Sulfamethoxazole |
≥ 4/76 | R | dfrA12 |
| Polymyxin | Colistin | ≥ 64** | R | IS5 disruption of mgrB gene |
| Tetracycline | Tigecycline | ≥ 256* | R | oqxAB§, acrAB§ |
| Fosfomycin | Fosfomycin | ≥ 1024* | R | fosA |
| Others | Nitrofurantoin | 128 | R | |
| Name of the antibiotic combination (ETEST) | Result of synergy test | |||
| Meropenem + Tigecycline | No zone | |||
| Meropenem + Ertapenem | No zone | |||
| Meropenem + Fosfomycin | No zone | |||
| Meropenem + Gentamicin | Very small zone of inhibition | |||
| Ceftazidime/Avibactam + Aztreonam | A large zone of Inhibition | |||
* ETEST method.
**Broth Micro Dilution method.
§No genetic evidence was found to infer overexpression.