Table 4.

Effects of AmpR mutants against production of class C β-lactamase in E. cloacae ATCC 13047 and three clinical isolates

Plasmidβ-Lactamase activity (U/mg of protein)a
KU3261KU3262KU3263ATCC 13047
<0.020.06<0.020.07
pKU4110.020.03<0.020.06
pKU4126.966.401.721.38
pKU4132.562.010.340.78
pKU4154.824.340.931.07
  • a One unit of β-lactamase activity was defined as the amount of β-lactamase that hydrolyzed 1 μmol of cephalothin in 1 min at 30°C.