Synergistic potential of ceftazidime plus amikacin or levofloxacin against Pseudomonas aeruginosa as determined using a checkerboard and a disk diffusion technique.

The synergistic potential of ceftazidime plus amikacin or levofloxacin was assessed against 61 Pseudomonas aeruginosa isolates with variable susceptibility patterns to the 3 antibiotics. A checkerboard broth method and a disk diffusion method were used and compared. The latter, also easy to perform as a triple-disk assay, could be a helpful laboratory screening tool for drug synergism to drive possible combination treatments.