TABLE 2.
MICs of β-lactams and β-lactamase inhibitor combinations for E. coli MV1190 producing the TEM-1 and mutant TEM β-lactamases
| Strain or amino acid changes from TEM-1a | Designation | MIC (μg/ml)b
|
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AMX | AMX + CLAc | TIC | TIC + CLAc | PIP | PIP + TZBd | CLD | CTX | CAZ | CAZ + CLAc | FEP | AZM | TEM | ||
| TEM-1e | TEM-1 | >1,024 | 256 | >1,024 | 256 | 128 | 32 | 64 | 0.06 | 0.5 | 0.25 | 0.12 | 0.25 | 4 |
| M69L | TEM-33 | >1,024 | >1,024 | >1,024 | 1,024 | 128 | 64 | 16 | 0.06 | 0.5 | 0.25 | ≤0.06 | 0.25 | 4 |
| M69L, N276D | TEM-35 | >1,024 | >1,024 | 1,024 | 512 | 128 | 32 | 16 | 0.06 | 0.25 | 0.25 | ≤0.06 | 0.12 | 4 |
| R244C | TEM-31 | 1,024 | 512 | 64 | 64 | 8 | 4 | 2 | 0.06 | 0.25 | 0.12 | ≤0.06 | 0.12 | 4 |
| G238S | TEM-19 | >1,024 | 16 | 1,024 | 16 | 32 | ≤1 | 32 | 1 | 0.5 | 0.25 | 0.12 | 0.5 | 4 |
| G238S, M69L | >1,024 | 32 | 512 | 16 | 32 | ≤1 | 32 | 0.25 | 0.25 | 0.25 | 0.12 | 0.25 | 8 | |
| G238S, M69L, N276D | >1,024 | 128 | 512 | 32 | 32 | ≤1 | 32 | 0.12 | 0.25 | 0.25 | 0.25 | 0.12 | 4 | |
| G238S, R244C | 1,024 | 128 | 64 | 16 | 8 | 2 | 4 | 0.06 | 0.25 | 0.25 | ≤0.06 | 0.12 | 4 | |
| G238S, E104K | TEM-15 | >1,024 | 16 | 1,024 | 32 | 32 | ≤1 | 32 | 8 | 8 | 0.25 | 0.25 | 4 | 8 |
| G238S, E104K, M69L | >1,024 | 32 | 1,024 | 64 | 32 | ≤1 | 32 | 4 | 4 | 0.25 | 0.25 | 1 | 4 | |
| G238S, E104K, M69L, N276D | TEM-50 | >1,024 | 128 | 1,024 | 128 | 32 | ≤1 | 32 | 4 | 4 | 0.5 | 0.5 | 2 | 4 |
| G238S, E104K, R244C | 1,024 | 64 | 256 | 64 | 8 | ≤1 | 4 | 0.06 | 0.25 | 0.25 | 0.25 | 1 | 4 | |
| R164S | TEM-12 | >1,024 | 32 | 1,024 | 32 | 64 | 2 | 32 | 0.12 | 8 | 0.25 | 1 | 1 | 8 |
| R164S, M69L | >1,024 | 256 | 512 | 64 | 32 | ≤1 | 8 | 0.12 | 8 | 0.25 | 0.5 | 1 | 4 | |
| R164S, M69L, N276D | >1,024 | 1,024 | 512 | 128 | 32 | 2 | 8 | 0.06 | 8 | 2 | 0.5 | 0.5 | 4 | |
| R164S, R244C | 1,024 | 256 | 16 | 8 | 4 | 2 | 2 | 0.06 | 0.25 | 0.25 | ≤0.06 | 0.12 | 4 | |
| R164S, E104K | TEM-26 | >1,024 | 16 | >1,024 | 32 | 64 | ≤1 | 8 | 1 | 64 | 0.5 | 1 | 16 | 8 |
| R164S, E104K, M69L | >1,024 | 64 | 1,024 | 64 | 64 | 2 | 8 | 0.5 | 64 | 2 | 1 | 16 | 4 | |
| R164S, E104K, M69L, N276D | >1,024 | 256 | 512 | 128 | 32 | 2 | 8 | 0.12 | 64 | 8 | 1 | 4 | 4 | |
| R164S, E104K, R244C | 512 | 64 | 128 | 32 | 32 | 8 | 2 | 0.06 | 4 | 1 | 0.25 | 1 | 8 | |
| E. coli MV1190 (recipient strain) | 8 | 4 | 2 | 2 | ≤1 | ≤1 | 2 | 0.06 | 0.12 | 0.12 | ≤0.06 | 0.12 | 4 | |
M69L refers to an amino acid substitution of leucine for methionine at position 69 in the TEM-1 β-lactamase protein sequence. The single amino acid codes for the other substitutions are as follows: N, asparagine; D, aspartate; G, glycine; R, arginine; C, cysteine; S, serine; E, glutamate; and K, lysine.
AMX, amoxicillin; CLA, clavulanate; TIC, ticarcillin; PIP, piperacillin; TZB, tazobactam; CLD, cephaloridine; CTX, cefotaxime; CAZ, ceftazidime; FEP, cefepime; AZM, aztreonam; TEM, temocillin.
Fixed concentration of clavulanate (2 μg/ml).
Fixed concentration of tazobactam (4 μg/ml).
TEM with amino acid modifications engineered to be identical to natural TEM-1.