DOI: 10.1128/AAC.48.12.4528-4531.2004
Article Figures & Data
Tables
- TABLE 1.
MICs of β-lactams for E. aerogenes LOR and CF23.04 isolates and for recombinant E. coli DH10B(pBK-TEM-121), DH10B(pBK-TEM-24), and DH10B
β-Lactama MIC (μg/ml) for the following isolateb: E. aerogenes LOR E. coli DH10B(pBK-TEM-121) E. aerogenes CF24.03 E. coli DH10B(pBK-TEM-24) E. coli DH10B Amoxicillin >512 >512 >512 >512 2 Amoxicillin-CLA 16 32 512 4 2 Ticarcillin >512 >512 >512 512 1 Ticarcillin-CLA 128 256 128 32 1 Piperacillin 32 64 128 128 1 Piperacillin-TZB 4 8 16 8 1 Cephalothin 8 16 >512 >512 4 Cefoxitin 4 2 128 2 2 Cefuroxime 8 8 >512 256 0.5 Ceftriaxone <0.06 <0.06 32 8 <0.06 Cefotaxime <0.06 <0.06 32 8 <0.06 Ceftazidime 128 256 512 256 <0.06 Aztreonam 8 16 512 256 0.06 Cefepime 2 4 4 4 0.06 Cefpirome 2 4 4 4 0.06 Imipenem 0.06 0.06 0.06 0.06 0.06 ↵ a CLA, clavulanic acid at 2 μg/ml; TZB, tazobactam at 4 μg/ml.
↵ b E. aerogenes isolate LOR produced β-lactamase TEM-121, whereas E. aerogenes CF24.03 produced TEM-24 and AmpC-type β-lactamases. Recombinant E. coli DH10B(pBK-TEM-121) and E. coli DH10B(pBK-TEM-24) produced β-lactamases TEM-121 and TEM-24, respectively.
- TABLE 2.
Kinetic parameters of β-lactamases TEM-121 and TEM-24a
β-Lactam TEM-121 TEM-24 kcat (s−1) Km (μM) kcat/Km (mM−1 · s−1) kcat (s−1) Km (μM) kcat/Km (mM−1 · s−1) Benzylpenicillin 25 15 1,700 20 9 2,200 Amoxicillin 10 500 20 6 55 110 Ticarcillin 10 75 140 10 60 160 Piperacillin 7 15 140 6 6 1,000 Cephaloridine 70 270 260 90 90 1,000 Cephalothin 20 420 50 30 30 1,000 Cefuroxime >5 >700 1 45 330 140 Ceftriaxone >2 >500 4 10 10 1,000 Cefotaxime 0.5 430 10 8.5 25 340 Ceftazidime 40 150 270 120 180 670 Cefepime 6 40 150 9 90 100 Cefpirome 30 360 80 45 310 145 Aztreonam 6.5 80 80 16 55 290 ↵ a Values are the means of results from at least three independent experiments.
