TIME-KILL STUDY OF THE ACTIVITY OF TROVAFLOXACIN COMPARED WITH CIPROFLOXACIN, SPARFLOXACIN, METRONIDAZOLE, CEFOXITIN, PIPERACILLIN AND PIPERACILLIN TAZOBACTAM AGAINST 6 ANAEROBES/

A time-kill method was developed to examine the killing kinetics of tr ovafloxacin, ciprofloxacin, sparfloxacin, metronidazole, cefoxitin, pi peracillin and piperacillin/tazobactam against one strain each of Bact eroides fragilis, Bacteroides thetaiotaomicron, Prevotella melaninogen ica, Fusobacterium mortiferum, Peptostreptococcus magnus and Clostridi um perfringens. Solutions and suspensions were prepared inside an anae robic glove box, using syringes and prereduced broth. Bottles were the n incubated outside the chamber and viability counts determined after incubation for 0, 6, 24 and 48 h in a shaking water bath, avoiding int roduction of air. Bacteriostatic/bactericidal concentrations (mg/L) af ter 48 h for the six strains were: trovafloxacin, 0.03-1/0.03-1; cipro floxacin, 0.25-16/0.25-32; sparfloxacin, 0.06-2/0.06-8; metronidazole 1-64/1-64; cefoxitin, 0.125-16/0.125-32; piperacillin, 0.125-64/0.125- 64; piperacillin/tazobactam, 0.06-2/0.125-8. Bacteriostatic levels wer e within two dilutions of broth MICs. By this time-kill method, trovaf loxacin had the lowest bacteriostatic concentrations of all compounds tested.