title: The in-vitro activity and tentative breakpoint of gemifloxacin, a new fluoroquinolone.
abstract: The in-vitro activity of gemifloxacin, a new fluoroquinolone, against a wide range (c. 700) of recent clinical isolates, was compared with that of three other fluoroquinolones and other relevant agents. Gemifloxacin inhibited 90% of the Enterobacteriaceae strains at 0.5 mg/L or less, exceptions being Serratia spp. (MIC(90) 1 mg/L) and strains possessing a putative mechanism of resistance to fluoroquinolones. Ninety per cent of Pseudomonas aeruginosa were inhibited by 4 mg/L. Gemifloxacin had good activity against respiratory pathogens, with 90% of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis being inhibited by 0.06 mg/L or less. Staphylococcus aureus (MSSA) were highly susceptible (MIC(90) 0.06 mg/L) but MRSA less susceptible (MIC(90) 8 mg/L) to gemifloxacin. Enterococcus spp. were markedly more susceptible to the study agent than to ciprofloxacin. Gemifloxacin showed good activity against Bacteroides fragilis (MIC(90) 0.5 mg/L) and anaerobic cocci. A tentative in-vitro breakpoint of 0.5 mg/L was studied using a 1 microg disc content for all genera except Pseudomonas where a 5 microg disc content was employed. The false sensitivity reporting rate was 0.5% and false resistance rate was 6.0%, which was considered acceptable. In conclusion, gemifloxacin is a highly active fluoroquinolone that should prove clinically useful in the treatment of a wide range of infections. Susceptibility testing criteria have been developed that should prove robust in a clinical laboratory.
authors.affiliation: Department of Medical Microbiology, City Hospital NHS Trust, Birmingham, UK.
authors.forename: R
authors.initials: R
authors.lastname: Wise
authors.forename: J M
authors.initials: JM
authors.lastname: Andrews
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000382:microbiology; D005069:Evaluation Studies as Topic; D024841:Fluoroquinolones; D000077735:Gemifloxacin; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000592:standards; D009287:Naphthyridines / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D009287:Naphthyridines; D000077735:Gemifloxacin