Mean bacterial densities over 48 h for KPC-producing Klebsiella pneumoniae isolates with a tigecycline MIC of 1 μg/ml and a meropenem MIC of 8 μg/ml. (A) Monotherapy models. Thick solid line, control; closed circles, tigecycline (isolate 351); open circles, tigecycline (isolate 382); closed triangles, meropenem (isolate 351); open triangles, meropenem (isolate 382). (B) Combination therapy models. Thick solid line, control; closed squares, tigecycline and meropenem (isolate 351); open squares, tigecycline and meropenem (isolate 382); closed diamonds, tigecycline and rifampin (isolate 351); open diamonds, tigecycline and rifampin (isolate 382). The lower limit of detection (dashed line) was set to 101 CFU/ml.