Mean bacterial densities over 48 h for KPC-producing Klebsiella pneumoniae isolates with a tigecycline MIC of 2 μg/ml and a meropenem MIC of 64 μg/ml. (A) Monotherapy models. Thick solid line, control; closed circles, tigecycline (isolate 362); closed triangles, meropenem (isolate 362). (B) Combination therapy model. Thick solid line, control; closed squares, tigecycline and meropenem (isolate 362). The lower limit of detection (dashed line) was set to 101 CFU/ml.