Efficacy of trovafloxacin in an in vitro pharmacodynamic simulation of an intraabdominal infection

An in vitro model simulating trovafloxacin concentrations in human serum af ter standard doses was used to investigate the activity of this drug with t ime against Bacteroides fragilis, Escherichia coil, Enterococcus faecalis a nd Staphylococcus aureus. Antibiotic concentrations used for each incubatio n period were: 4.24 mg/l (0-1 h), 3.69 mg/l (1-3 h), 3.25 mg/l (3-6 h), 2.3 8 mg/l (6-8 h), 1.35 mg/l (8-24 h). A 99.9% initial inoculum reduction (>3 log(10) cfu/ml) was defined as bactericidal activity. Bactericidal activity against these organisms was obtained with trovafloxacin after the first ho ur of incubation, and similar activity was obtained against B. fragilis, E. faecalis and S. aureus after 3 h, when they were tested individually. When the strains were tested as mixed culture, there was bactericidal activity against E. coli after 1 h incubation and after 3 h for S. aureus. This acti vity was observed against B. fragilis and E. faecalis after 6 h incubation in the mixed culture assays and after 3 h when organisms were tested indivi dually. Regrowth was not observed over a 24 h period. These data show that trovafloxacin might be effective in intraabdominal infections caused by mix ed aerobic and anaerobic microorganisms. (C) 1999 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved.