Table 1.

MICs and error rates obtained for 107 single-patient clinical isolates of the Acinetobacter baumannii-calcoaceticus complex tested for susceptibility to imipenem, meropenem, and doripenem by manual and automated methods compared to BMD by using CLSI, FDA, and EUCAST criteria

Drug and methodaMIC (μg/ml)Resultb using the following criteria:
CLSIcFDAdEUCASTe
50%90%% S% VME% ME% mE% S% VME% ME% mE% S% VME% ME% mE
Imipenem
    DD39.60.00.91.939.60.00.91.931.817.82.8NA
    ET≥32≥3239.30.00.93.739.30.00.93.713.15.66.5NA
    MicroScan≥8≥843.03.71.92.843.03.71.92.838.325.21.9NA
    Phoenix≥8≥841.11.90.92.841.11.90.92.837.425.20.9NA
    Vitek 2≥16≥1639.30.90.04.739.30.90.04.738.325.20.9NA
    BMD≥16≥1637.437.415.0
Meropenem
    DD38.30.00.03.738.30.00.03.78.40.912.1NA
    ET≥32≥3236.40.00.03.736.40.00.03.719.64.74.7NA
    MicroScan≥8≥838.30.00.93.738.30.00.93.737.418.70.9NA
    Phoenix≥8≥839.21.90.94.739.21.90.94.735.517.80.9NA
    Vitek 2≥16≥1639.30.00.94.739.30.00.94.736.417.80.9NA
    BMD≥16≥1635.535.519.6
Doripenem
    DDNANANANA35.530.80.9NA7.53.70.0NA
    ET≥32≥32NANANANA6.52.80.0NA6.52.80.0NA
    Vitek 2≥8≥8NANANANA21.517.80.0NA21.517.80.0NA
    BMD≥16≥16NA3.73.7
  • a DD, disk diffusion; ET, Etest; Vitek 2, Vitek 2 cards (AST-GN24 card and AST-XN04 extension card).

  • b S, susceptible; VME, very major errors; ME, major errors; mE, minor errors; NA, not applicable (intermediate breakpoints for doripenem were not defined).

  • c CLSI breakpoints for imipenem/meropenem were as follows: for susceptibility, ≤4 μg/ml (≥16 mm); for intermediacy, 8 μg/ml (14 to 15 mm); for resistance, ≥16 μg/ml (≤13 mm) (3).

  • d FDA breakpoints were as follows: for imipenem/meropenem, ≤4 μg/ml (≥16 mm) for susceptibility and ≥16 μg/ml (≤13 mm) for resistance; for susceptibility to doripenem, ≤1 μg/ml (≥17 mm).

  • e EUCAST breakpoints were as follows: for imipenem, ≤2 μg/ml (≥23 mm) for susceptibility and ≥8 μg/ml (≤17 mm) for resistance; for meropenem, ≤2 μg/ml (≥21 mm) for susceptibility and ≥8 μg/ml (≤15 mm) for resistance; for doripenem, ≤1 μg/ml (≥21 mm) for susceptibility and ≥4 μg/ml (≤15 mm) for resistance (6).