TABLE 1.
Summary of the MIC values, detected genes, and gene products in A. baumannii ST1 (GA60)a
| Antibiotic(s) | MIC (μg/ml) | Gene(s) detected | Gene product/function | Comment | Reference(s) |
|---|---|---|---|---|---|
| Ceftazidime | ≥64 | blaADC | Intrinsic chromosomal β-lactamase (Acinetobacter-derived cephalosporinase) | ISAba1 element upstream of blaADC detected | 12 |
| Cefotaxime | ≥64 | ||||
| Cefepime | ≥64 | ||||
| Imipenem | ≥16 | blaOXA-40-like | Class D (OXA) β-lactamase (carbapenem-hydrolyzing oxacillinase) | 8 | |
| Meropenem | ≥16 | blaOXA-72 | |||
| blaOXA-51-like | Intrinsic chromosomal oxacillinase (carbapenem-hydrolyzing oxacillinase) | ISAba1 was not found, no expression | 12 | ||
| blaTEM-1 | Class A broad-spectrum β-lactamase | Stop codon detected near the 3' end, no expression | 10, 11 | ||
| Piperacillin | ≥128 | blaOXA-40-like | Generally, OXA enzymes are resistant to inhibition by clavulanate, sulbactam, and tazobactam | 20 | |
| Piperacillin-tazobactam | ≥128 | blaOXA-72 | |||
| Gentamicin | >16 | aac(3)-Ia | Aminoglycoside N-acetyltransferase | Resistance to gentamicin | 19 |
| Tobramycin | >16 | ||||
| Amikacin | ≥64 | aac(6')-Ib | Aminoglycoside N-acetyltransferase | Resistance to tobramycin, amikacin, netilmicin** | |
| aadA1, aadA1a | Aminoglycoside O-nucleotidyltransferases | Resistance to spectinomycin** and streptomycin** | |||
| aphA-7 | Aminoglycoside O-phosphotransferase | Resistance to kanamycin** and neomycin** | |||
| Trimethoprim-sulfamethoxazole | ≥320 | sul1 | Dihydropteroate synthase | Resistance to sulfamethoxazole | *** |
| dfrA18 | Dihydrofolate reductase | Resistance to trimethoprim | |||
| Chloramphenicol | ND | catA1 | Chloramphenicol acetyltransferase | Resistance to chloramphenicol | *** |
| Tetracyclines | ND | tet(A) | Efflux pump | Resistance to tetracycline | *** |
| Ciprofloxacin | ≥4 | gyrA | DNA gyrase A | Mutations in quinolone resistance-determining-region (QRDR) of GyrA Ser83Leu | 13 |
| parC | Topoisomerase IV, subunit A | Mutations in quinolone resistance-determining-region (QRDR) of ParC Ser80Leu | |||
| Colistin | 16 | pmrCAB | Two-component response regulator and sensor kinase PmrA/B, expression of genes implicated in lipid A modification | Colistin mutations in PmrC (R125P, I131V, H499R*), PmrA (A80V), and PmrB (R231T, P360Q*) | 7, 15 |
a
Abbreviations and symbols: ND, not determined; *, alteration has previously been associated with resistance to colistin; **, not included in this research; ***, included in microarray panel.