title: In vitro activity of OPC-17116.
abstract: The in vitro activity of OPC-17116, a new C-5 methyl fluoroquinolone, was compared with the activities of other fluoroquinolones. OPC-17116 inhibited 50% of the members of the family Enterobacteriaceae tested and 90% of Haemophilus influenzae, Neisseria species, and Moraxella catarrhalis isolates at less than or equal to 0.25 microgram/ml. At less than or equal to 2 micrograms/ml, 90% of the Enterobacteriaceae were inhibited, which was comparable to or better than the activities of fleroxacin, ofloxacin, and lomefloxacin but less than the activity of ciprofloxacin. OPC-17116 inhibited 90% of the staphylococci tested at less than or equal to 0.25 micrograms/ml, but it did not inhibit methicillin-resistant, ciprofloxacin-resistant Staphylococcus aureus or Staphylococcus epidermidis. Group A, B, C, F, and G streptococci and Streptococcus pneumoniae were inhibited by less than or equal to 0.5 microgram/ml, being four-fold more active than ciprofloxacin and ofloxacin. Tosufloxacin was the most active agent tested against gram-positive cocci. OPC-17116 inhibited Bacteroides fragilis at 4 micrograms/ml. There was a minimal effect of inoculum size on MIC, and the MBCs were within 1 dilution of the MICs. The activity of OPC-17116 was decreased at pH 6 and in the presence of high Mg2+ concentrations, but it was unaffected by human serum. OPC-17116 showed a postantibiotic effect against Pseudomonas aeruginosa and Staphylococcus aureus similar to the postantibiotic effects reported for other fluoroquinolones. The frequency of spontaneous single-step resistance was low (less than 10(-9)), but repeated passage of organisms in the presence of OPC-17116 resulted in the selection of resistant isolates.
authors.affiliation: Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
authors.forename: H C
authors.initials: HC
authors.lastname: Neu
authors.forename: W
authors.initials: W
authors.lastname: Fang
authors.forename: J W
authors.initials: JW
authors.lastname: Gu
authors.forename: N X
authors.initials: NX
authors.lastname: Chin
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D004352:Drug Resistance, Microbial; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D010879:Piperazines / Q000494:pharmacology*; D015363:Quinolones / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D010879:Piperazines; D015363:Quinolones; C075375:grepafloxacin