TABLE 1.

MICs of antibiotics for the E. coli isolates that produced CTX-M-like ESBLs

AgentMIC (μg/ml) for isolate (source/pI[s] inhibited by clavulanate)
Isolate 1 (Falls Church, Va.; urine/9.4 and 7.4)Isolate 4 (Falls Church, Va.; urine/9.4 and 7.4)Isolate 2 (Falls Church, Va.; urine/9.4, 7.4, and 5.4)Isolate 3 (Falls Church, Va.; urethra/9.4, 7.4, and 5.4)Isolate 5 (Boise, Idaho; urine/9.0, 7.9, and 5.4)Isolate 6 (Cleveland, Ohio; sputum/ 9.4 and 7.4)Isolate 7 (Seattle, Wash.; blood/9.4)Isolate 8 (El Paso, Tex.; urine/ 8.0 and 5.4)Isolate 9 (El Paso, Tex.; sputum/ 8.0 and 5.4)
Ceftriaxone>32>32>32>32>32>32>32>32>32
Cefotaxime>64>64>64>64>64>64>641632
Cefotaxime-clavulanatea0.250.250.120.12≤0.060.12≤0.06≤0.06≤0.06
Ceftazidime6412812832216160.50.5
Ceftazidime-clavulanatea0.50.50.50.250.120.120.120.060.06
Cefepime>128>128>128>12864>1286424
Cefepime-clavulanateb0.060.060.12≤0.03≤0.03≤0.03≤0.03≤0.03≤0.03
Aztreonam>128>128>128128166432≤14
Cefoxitin>1616>1616888≤416
Imipenem0.250.250.250.120.120.120.120.250.12
Piperacillin-tazobactamc16832≤4≤48≤4≤4≤4
Ciprofloxacin>4>4>4>4≤0.25>4>4>4>4
Amikacin8≤432≤4≤432≤4≤4≤4
  • a Clavulanate at a fixed concentration of 4 μg/ml.

  • b Clavulanate at a fixed concentration of 10 μg/ml.

  • c Tazobactam at a fixed concentration of 4 μg/ml.