Table 1

Results of tests of cefdinir with and without the concomitant presence of amoxicillin-clavulanate (Amox-Clav) by broth dilution and disk diffusion testing

ESBL group (no. of isolates)MIC tested aloneCefdinir MIC tested with Amox-Clava% susceptibleb% detected by disk approximationc
CefdinirAmox-Clavd
MIC50eMIC90fRangeMIC50MIC90RangeMIC50MIC90Range
CTX-M (55)g>16>162–>1632>322–>320.251≤0.03–>1690.996.4
SHV (40)h16>160.5–>1632>322–>320.06>16≤0.03–>1660.097.5
CTX-M + SHV (6)i>16>168–>1632>3216–>320.25>16≤0.03–>1680.0100
  • a Cefdinir was tested in standard 2-fold dilution series in the presence of a fixed concentration of 8 μg/ml amoxicillin and 4 μg/ml clavulanate.

  • b Susceptible to cefdinir at ≤1 μg/ml when tested in the presence of amoxicillin-clavulanate.

  • c Percent of those susceptible to the drug combination by MIC that were detected by disk approximation testing.

  • d Activity of the amoxicillin-clavulanate combination expressed as the amoxicillin component.

  • e MIC50, MIC required to inhibit 50% of isolates.

  • f MIC90, MIC required to inhibit 90% of isolates.

  • g The following isolates were included: 43 E. coli, 9 Klebsiella spp., 2 Enterobacter spp., and 1 Morganella morganii.

  • h The following isolates were included: 10 E. coli, 25 Klebsiella spp., and 5 Enterobacter spp.

  • i Included 2 E. coli isolates and 3 Klebsiella spp. isolates.