[In vitro activity of a new fluoroquinolone, marbofloxacin (RO 09-1168) against strictly anaerobic bacteria and some bacteria from human fecal flora].

As recommended by the EEC, the in vitro activity of a veterinary quinolone has to be evaluated on human strains isolated from the gut and especially against anaerobes. Thus, the MICs for Marbofloxacin were determined by the reference agar method (Norma NCCLS M11 A3) using Wilkins Chalgren medium for the 124 anaerobic strains and Mueller Hinton agar for E. coli, Proteus, Enterococcus and Lactobacillus. On the whole aerobes, the activity of Marbofloxacin was equal or slightly greater to that of ofloxacin. The modal MIC was 0.03 mg/l for Enterobacteriaceae, 2 mg/l and 16 mg/l for Enterococcus and Lactobacillus strains, respectively. Considering the anti-anaerobic activity of this new drug, in comparison with that of ofloxacin, MICs for ofloxacin were generally one log2 higher for Gram negative bacilli and two log2 higher for Gram positive bacilli. Modal MICs for marbofloxacin were 0.12 mg/l for Clostridium perfringens, 0.5 mg/l for Bacteroides fragilis, Fusobacterium, Prevotella, and Peptostreptococcus strains, 1 mg/l for Bifidobacteria, 2 mg/l for non-fragilis members of the B. fragilis group, and 4 mg/l for C. difficile strains, respectively. It appears in vitro that Marbofloxacin was a more potent agent than ofloxacin on the whole anaerobes.