TABLE 5.

Susceptibilities of PAO1 and ampD null mutants to ceftazidime and aztreonam in the presence or absence of EtBuPUGa

StrainMICb (mg ml−1)Antibiotic clearing radius (mm)c
CeftazidimeAztreonamCeftazidimeAztreonam
−I+I−I+I−I+I−I+I
PAO110.510.2511.413.112.515.1
PAΔD8463
PAΔDh20.750.1910.2510.112.311.814.0
PAΔDh310.51.50.75
PAΔDDh2126168
PAΔDDh34848168
PAΔDh2Dh30.750.750.50.25
PAΔDDh2Dh3484824129.29.510.711.9
  • a The bacterial strains were treated with the NagZ selective inhibitor EtBuPUG (+I) or were not treated with EtBuPUG (−I).

  • b The MIC was determined by the broth microdilution method. Measurements were performed in triplicate.

  • c Sensitivity was determined by an agar diffusion assay. Filter discs (diameter, 6 mm) loaded with 30 μg of ceftazidime or aztreonam with or without the inhibitor EtBuPUG were placed onto an agar plate inoculated with the indicated strain. After incubation overnight, the radius (from the center of the disc) of the zone of clearance was measured.