TABLE 1.

Antimicrobial susceptibilities

Antibiotic (s)MIC (μg/ml)
C. freundii 29dtCf29eE. coli Top 10
Cefotaximea32160.12
Cefotaxime and clavulanic acida,c0.120.120.12
Cefdinirb64320.25
Ceftazidimea10.50.25
Ceftazidime and clavulanic acida,c0.250.50.25
Ceftriaxonea64320.12
Aztreonama210.25
Cefepimea41≤0.06
Cefepime and clavulanic acida,c≤0.03≤0.03≤0.03
Cefpodoximea64320.5
Cefpodoxime and clavulanic acida,c20.250.5
Cefoxitina≤4≤4≤4
Imipenema0.120.120.12
Ampicillina>32>322
Amoxicillin and clavulanic acida,c1644
Piperacillinb>256>2562
Piperacillin and tazobactamb,c112
  • a MICs determined using microbroth according to NCCLS guidelines.

  • b MICs determined using E-test.

  • c Clavulanate and tazobactam were used at fixed concentrations of 4 μg/ml.

  • d The pI(s) of the β-lactamases produced by C. freundii were 5.4, 8.0, and 8.9.

  • e The pI of the β-lactamase produced by tCf29 was 8.0.