Aminoglycoside susceptibility testing by Etest before and after passaging on culture mediaa

Before passageAfter passageBefore passageAfter passage
MIC (μg/ml)CategoryMIC (μg/ml)CategoryMIC (μg/ml)CategoryMIC (μg/ml)Category
ATCC 259221S1S4S4S
PPT 164R16R256R64R
PPT 232R16R256R64R
SON 116R16R256R64R
SON 2b16R2S256R8S
SON 3b16R4S256R16S
SON 416R16R256R128R
SON 5b8I4S128R16S
  • a S, susceptible; I, intermediate; R, resistant. Values of Etest were rounded up to the next highest 2-fold dilution of microdilution assays and interpreted according to CLSI guidelines.

  • b Only isolates SON 2, 3, and 5 completely reverted after passage on culture media.