TABLE 1

Parent strains used for mutant selection

Resistance mechanism(s)No. of parent strains used for mutant selection
E. coliKlebsiellaEnterobacterCitrobacter
None (no AmpC, ESBL, or carbapenemase) (control)5545
ESBL5422
AmpC (plasmid or derepressed)2255
KPC2522
MBLs1 NDM, 2 VIM3 NDM, 2 VIM, 2 IMP2 NDM, 2 VIM2 NDM, 2 VIM
OXA-482221