The modal MIC for P. aeruginosa ATCC 27853 using ceftazidime E test strips was 5 µg/ml. Figure 3 shows concentration-time profiles for central and peripheral compartments. Mean central compartment ceftazidime concentrations were 23.5 and 20.9 µg/ml for models A and B, respectively. Ceftazidime penetration into the peripheral compartment occurred more rapidly in model A than in model B (Figure 4). The percentage of penetration from 0-4 hours was 53% greater for model A ( Table 1 ); however, the value over the entire study period was similar for both models (4% difference). No appreciable change in colony counts was observed before 2 hours in either model (lag effect; Figure 5); however, thereafter, counts were higher in the growth control curve and killing was more extensive in model A than in model B. No bacterial regrowth was observed in either model. The percent effect was greater in model A than in model B from both 0-4 hours (64% greater) and 0-24 hours (38% greater).
Percent of ceftazidime penetration into peripheral compartments from 0-4 hours. Model A (), model B ().
Surviving colony counts versus time. Model A growth control curve (), model A kill curve (), model B growth control curve (), model B kill curve (). CFU = colony-forming units.
Pharmacotherapy. 2003;23(5) © 2003 Pharmacotherapy Publications
Copyright © 1999, Pharmacotherapy Publications, Inc., All rights reserved.
This article was prepared by Charles R. Bonapace, Pharm.D., in his private capacity. No official support or endorsement by the U.S. Food and Drug Administration is intended or should be inferred.
Cite this: Assessment of Differences in Antimicrobial Effect Determined with Two In Vitro Pharmacodynamic Models: Impact of Surface Area to Volume Ratio - Medscape - May 01, 2003.