Novel Microdilution Method to Assess Double and Triple Antibiotic Combination Therapy In Vitro

Figure 3

Evaluation of double and triple combinations of ciprofloxacin, amikacin, and ceftazidime against isolate PA14 by time-kill assay in a chemostat model. Isolate PA14 was added at 1 to 5 × 10⁵ CFU/mL to bottles containing cation-adjusted Muller Hinton broth. The first doses of the antibiotics, alone or in combination, were added at concentration equivalent to double of their minimum inhibitory concentrations after 10 hours of inoculation. The second and third doses of the antibiotics were added at 30 and 60 hours of incubation. The flow rate was kept at 10 mL/h throughout the experiment. AMK, amikacin; CIP, ciprofloxacin; CAZ, ceftazidime.