IN-VITRO PHARMACODYNAMICS OF CEFTAZIDIME AGAINST PSEUDOMONAS-AERUGINOSA ISOLATES FROM CYSTIC-FIBROSIS PATIENTS

The concentration/MIC (C/MIC) ratio maximizing the bactericidal activi ty of ceftazidime against 10 Pseudomonas aeruginosa isolates from cyst ic fibrosis patients was identified. Bactericidal activity was assesse d by determining the percent difference in the area under the killing curve at each C/MIC ratio for all of the isolates from that of their g rowth control. The percent effect at each C/MIC ratio was fitted to a sigmoidal E-max model with maximum bactericidal activity defined as th e C/MIC ratio that produced an effect that was 90% of the E-max. Our r esults suggest that at least some isolates may require higher C/MIC ra tios than previously reported for maximal activity.