TABLE 2.

MICs of β-lactam antibiotics for various strains testeda

β-LactamMIC (μg/ml)
Xc11Xc11RMXc11RM(pFJ-ampR1)
Ampicillin>2564>256
Oxacillin>25664>256
Piperacillin-tazobactam25624256
Carbenicillin25616512
Cefoxitin1283128
Cefotaxime32832
Imipenem40.254
  • a All tests were performed with Etest strips, except that carbenicillin and cefotaxime were tested by the microdilution method.