Vol.55 No.S-1 October 2007

In vitro antibacterial activity of garenoxacin

Masahiro Takahata, Yoshiko Fukuda, Naoko Futakuchi, Yoko Sugiura, Harumi Hisada, Shingo Mizunaga, Naoko Oogake, Yuko Ito, Yuko Shinmura, Masatoshi Nakatani, Tomoaki Tanaka, Takashi Komeno, Tomoko Kamiyama, Junichi Mitsuyama and Yozo Todo

Research Laboratories, Toyama Chemical Co., Ltd., 2-4-1 Shimookui, Toyama, Japan

Abstract

We evaluated the in vitro antibacterial activity of garenoxacin mesilate hydrate (GRNX). Results are summarized as follows:
1. GRNX showed a broad spectrum of potent activity against Gram-positive and Gram-negative bacteria in both aerobic and anaerobic bacteria, Chlamydia spp., Mycoplasma pneumoniae and Legionella spp.
2. GRNX showed potent antibacterial activity against clinical isolates of Gram-positive bacteria. The MIC₉₀s of GRNX against methicillin-susceptible Staphylococcus aureus(MSSA) and Streptococcus spp., including penicillin-resistant Streptococcus pneumoniae(PRSP) were 0.05 μg/mL to 0.1 μg/mL and were 1/2 to 1/32 than that of levofloxacin(LVFX), gatifloxacin(GFLX), moxifloxacin(MFLX) ciprofloxacin(CPFX) and tosufloxacin(TFLX).
3. In Gram-negative bacteria, the MIC₉₀ of GRNX against Haemophilus influenzae, Moraxella catarrhalis and Klebsiella pneumoniae, major pathogens of respiratory tract infection, were 0.025 to 1.56 μg/mL, and were the same as that of other quinolones tested.
4. The MIC of GRNX against Chlamydophila pneumoniae and MIC₉₀ of GRNX against M. pneumoniae were 0.002 μg/mL to 0.008 μg/mL and 0.0313 μg/mL, respectively, and were lowest among quinolones tested. The MIC₉₀ of GRNX against Legionella pneumophila was the same as that of GFLX and more potent than that of other quinolones tested.
5. The in vitro antibacterial activity of GRNX was not influenced by the type of medium, medium pH, addition of human serum, or inoculum size.
6. The action of GRNX was bactericidal. The mutant prevention concentrations(MPCs) of GRNX against S. aureus and S. pneumoniae including quinolone-resistant strains were less than 1 μg/mL, and were lower than those of LVFX and GFLX.
7. The inhibitory effect of GRNX against DNA gyrase and topoisomerase IV of S. aureus and S. pneumoniae was more potent than that of LVFX and GFLX.
8. In an in vitro pharmacokinetic model simulating serum concentration of GRNX following 400 mg single oral administration, GRNX showed a potent bactericidal activity against quinolone-resistant S. pneumoniae.

Key word

garenoxacin, in vitro, antimicrobial activity

Received

April 27, 2007

Accepted

July 18, 2007

Jpn. J. Chemother. 55 (S-1): 1-20, 2007