Fig. 1

Time kill curves for IMP-1- or IMP-6-producing E. coli isolates with MEM or CMZ only, or both MEM and CMZ. E. coli isolate TUM13773 carrying bla_IMP-1. a and E. coli isolate E109 carrying bla_IMP-6. b were incubated in Mueller–Hinton II Broth (black circle) or supplemented with MEM (black up-pointing triangle), with CMZ (black diamond) or with combination of MEM and CMZ (square) at 37 °C. All the antibiotics were used at concentrations of 25% of their MIC for individual isolates. Viable cells per milliliter before incubation and after incubation for 3, 6, 9, and 24 h were counted on Muller Hinton II agar plates after overnight incubation at 37 °C. Assays were performed in duplicate and the logarithm of the average CFU/mL was plotted