TABLE 4.
Antibiotic susceptibility profiles of E. coli isolates at two cell densities
| Strain (enzyme) | Cell density (CFU/ml) | MIC (μg/ml)a
|
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Carbapenems
|
Cephalosporins
|
Monobactam: ATM | Penicillin with or without oxapenam
|
|||||||||
| MK-0826 | MERb | IPM | CTRX | CAZ | CTX | CPM | AM | AM/CA | CA | |||
| CL 5121 (SHV-1) | 9.6 × 105 | 0.016 | 0.03 | 0.12 | 0.06 | 0.25 | 0.06 | 0.06 | 0.06 | >512 | 16/8 | 32 |
| 9.6 × 106 | 0.25 [16] | 0.5 [16] | 0.5 [4] | 2 [32] | 8 [32] | 4 [64] | 4 [64] | >128 [>2,048] | >512 | 16/8 [1] | 32 [1] | |
| CL 5190 (TEM-10) | 1.4 × 106 | 0.06 | 0.016 | 0.06 | 4 | >128 | 1 | 4 | 64 | >512 | 8/4 | 16 |
| 1.4 × 107 | 0.06 [1] | 0.25 [16] | 0.12 [2] | >128 [>32] | >128 | 32 [32] | 128 [32] | >128 [>2] | >512 | 8/4 [1] | 64 [4] | |
| CL 5115 (TEM-1) | 1.0 × 106 | 0.008 | 0.03 | 0.25 | 0.03 | 0.25 | 0.06 | 0.03 | 0.06 | >512 | 16/8 | 32 |
| 1.0 × 107 | 0.008 [1] | 0.03 [1] | 0.25 [1] | 0.25 [8] | 0.5 [2] | 0.12 [2] | 0.12 [4] | 0.12 [2] | >512 | 16/8 [1] | 32 [1] | |
| CL 5120 (TEM-7) | 6.0 × 105 | 0.016 | 0.03 | 0.12 | 0.5 | 32 | 0.25 | 2 | 1 | >512 | 16/8 | 32 |
| 6.0 × 106 | 0.03 [2] | 0.12 [4] | 0.25 [2] | 16 [32] | 128 [4] | 4 [16] | 128 [64] | 32 [32] | >512 | 16/8 [1] | 32 [1] | |
| CL 5197 (TEM-12) | 1.3 × 106 | 0.12 | 0.03 | 0.12 | 1 | 64 | 0.5 | 4 | 2 | >512 | 16/8 | 16 |
| 1.3 × 107 | 0.12 [1] | 0.12 [4] | 0.25 [2] | 64 [64] | >128 [>2] | 8 [16] | >128 [>32] | >128 [>64] | >512 | 16/8 [1] | 64 [4] | |
| MB5503 (Bush group 1 β-lactamase) | 6.9 × 105 | 0.008 | 0.016 | 0.12 | 0.06 | 0.12 | 0.03 | 0.016 | 0.03 | 2 | 2/1 | 32 |
| 6.9 × 106 | 0.008 [1] | 0.03 [2] | 0.12 [1] | 0.06 [1] | 0.25 [2] | 0.06 [2] | 0.03 [2] | 0.06 [2] | 4 [2] | 4/2 [2] | 32 [1] | |
| DH5α (Bush group 1 β-lactamase) | 1.1 × 105 | 0.004 | 0.03 | 0.12 | ≤0.06 | 0.12 | ≤0.06 | ≤0.06 | ≤0.06 | 4 | 2/1 | 32 |
| 1.1 × 106 | 0.008 [2] | 0.06 [2] | 0.25 [2] | ≤0.06 | 0.25 [2] | ≤0.06 | ≤0.06 | 0.12 [≥2] | 4 [1] | 4/2 [2] | 32 [1] | |
| LS641 (Bush group 1 β-lactamase) | 8.2 × 105 | 0.008 | 0.03 | 0.25 | ≤0.06 | 0.25 | ≤0.06 | ≤0.06 | 0.12 | 8 | 4/2 | 32 |
| 8.2 × 106 | 0.12 [16] | 0.12 [4] | 0.5 [2] | 1 [≥16] | 1 [4] | 0.5 [≥8] | 0.5 [≥8] | 4 [32] | 8 [1] | 8/4 [2] | 64 [2] | |
| MB4903 (Bush group 1 β-lactamase) | 6.6 × 105 | 0.008 | 0.03 | 0.25 | ≤0.06 | 0.25 | 0.12 | ≤0.06 | 0.12 | 4 | 4/2 | 32 |
| 6.6 × 106 | 0.008 [1] | 0.03 [1] | 0.25 [1] | 0.25 [≥4] | 2 [8] | 0.25 [2] | 0.25 [≥4] | 2 [16] | 8 [2] | 8/4 [2] | 32 [1] | |
a
Fold MIC increases at 10× inoculum are shown in brackets. Fold MIC changes were calculated based on serial twofold antibiotic dilutions prior to rounding off of MIC values.
b
Antibiotic abbreviations are the same as for Table 3.