TABLE 5

Effects of cysteine addition on Amd resistance of clinical isolatesa

StrainRelevant phenotypeGrowth on MMAmd MIC (mg/liter)
M9M9 + CysNo Cys0.3 mM Cys0.75 mM Cys
DA5438Cys+YesYes0.1250.1250.125
DA28439CysbNoYes2420.25
DA14704CysNoYes320.1250.125
DA14709CysNoYes420.38
DA14710CysNoYes6480.125
DA14712CysNoYes32160.5
DA14713CysNoNo6440.125
DA14715CysNoYes1620.19
DA14718CysNoYes3280.38
DA14719CysNoYes160.50.094
DA24678CysNoYes48160.38
DA24686CysNoYes32160.19
DA24690CysNoYes32240.125
DA24692CysNoYes4860.19
  • a Shown are growth on M9 glucose minimal medium (MM) with or without cysteine added and Amd Etest MICs on MH plates with different concentrations of cysteine. DA5438 is E. coli MG1655, DA28439 is a constructed cysB knockout strain, and all of the other strains are Amdr clinical E. coli isolates with cysB mutations.

  • b cysB knockout.