Journal Article

<i>In vitro</i> activity of pazufloxacin, tosufloxacin and other quinolones against <i>Legionella</i> species

Futoshi Higa, Morikazu Akamine, Shusaku Haranaga, Masato Tohyama, Takashi Shinzato, Masao Tateyama, Michio Koide, Atsushi Saito and Jiro Fujita

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 56, issue 6, pages 1053-1057
Published in print December 2005 | ISSN: 0305-7453
Published online October 2005 | e-ISSN: 1460-2091 | DOI:
In vitro activity of pazufloxacin, tosufloxacin and other quinolones against Legionella species

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Objectives: The activities of pazufloxacin and tosufloxacin against Legionella spp. were evaluated in vitro and compared with those of other quinolones, macrolides and azithromycin.

Methods: The conventional MICs were determined by the microbroth dilution method. Intracellular activities of drugs were evaluated by a cfu count. The minimal extracellular concentration inhibiting intracellular growth of bacteria (MIEC) was determined by a colorimetric cytopathic assay.

Results: MICs of pazuloxacin and tosufloxacin at which 90% (MIC90) of isolates are inhibited in 76 different Legionella spp. strains (38 ATCC strains and 38 clinical isolates) were 0.032 and 0.016 mg/L, whereas the MIC90s of levofloxacin, ciprofloxacin, garenoxacin, erythromycin, clarithromycin and azithromycin were 0.032, 0.032, 0.032, 2.0, 0.125 and 2.0 mg/L, respectively. Pazufloxacin and tosufloxacin at 4× MIC inhibited intracellular growth of Legionella pneumophila SG1 (80-045 strain), as did other quinolones, clarithromycin and azithromycin, whereas erythromycin at 4× MIC did not. MIECs of pazufloxacin, tosufloxacin, levofloxacin, ciprofloxacin and garenoxacin for the strain were 0.063, 0.004, 0.016, 0.032 and 0.008 mg/L respectively, which were superior to those of macrolides and azithromycin. Pazufloxacin showed potent activity against three additional clinical isolates of L. pneumophila SG1, one clinical isolate each of L. pneumophila SG3 and SG5, as well as Legionella micdadei, Legionella dumoffii and Legionella longbeachae SG1.

Conclusions: Pazufloxacin and tosufloxacin, as well as other quinolones, were more potent than macrolides and an azalide. Present data warrant further study on the efficacy of these drugs in the treatment of Legionella infections.

Keywords: intracellular activity; MIEC; MIC; Legionnaires' diseases; fluoroquinolones

Journal Article.  2499 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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