Evaluation of two in vitro pharmacodynamic simulation models: Microfiltration versus centrifugation-filtration

Pharmacodynamic in vitro models that simulate serum antimicrobial concentra tions provide more information about the activity of an antibiotic than MIC s or traditional time-kill methods. The aim of this study was to compare tw o pharmacodynamic simulation models using ATCC strains of five different sp ecies and five antibiotics. In the first model (Centriprep-10 system), a fi ltration-centrifugation process was used to eliminate the antibiotic; in th e second model (microfiltration system) no centrifugation was necessary. Th e antibiotic concentrations tested were similar to those in serum after nor mal doses of cefuroxime, clarithromycin, ciprofloxacin, gentamicin and cefo taxime. No significant differences were observed in the killing rates betwe en the models except in the case of Haemophilus influenzae and cefotaxime. The new microfiltration model had the following advantages: lack of the car ry-over effect, the absence of centrifugation that could damage bacteria an d the possibility of increasing the number of incubation periods to give a better fit of the kinetic profile of man. (C) 2001 Elsevier Science B.V. an d the International Society of Chemotherapy. All rights reserved.