Antimicrobial Activity of a New Fluoroquinolone, DU-6859a, against Quinolone-Resistant Clinical Isolates of Pseudomonas aeruginosa with Genetic Alterations in the GyrA Subunit of DNA Gyrase and the ParC Subunit of Topoisomerase IV

• DOI: 10.1007/bf02491517
• Publication Date: 2006-09-19T06:35:31Z
• Authors: Masahiro Nakano; Takashi Deguchi; Mitsuru Yasuda; Shigehiko Ozeki; Yoshinori Nishino; Satoshi Ishihara; Yukimichi Kawada
• Keywords: Topoisomerase IV; Quinolone

The in vitro antimicrobial activity of DU-6859a, a new fluoroquinolone, was tested against 22 clinical isolates ofPseudomonas aeruginosa, including strains with fluoroquinolone resistance-associated alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV. The MICs of DU-6859a for 10 isolates with both altered GyrA and ParC and for 7 isolates with altered GyrA alone ranged from 1.56 to 25 μg/mL and from 0.78 to 6.25 μg/mL, respectively. The MIC of DU-6859a at which 90% of the strains were inhibited (MIC90) of these 17 isolates was 12.5 μg/mL. However, there was no significant difference between DU-6859a and the other quinolones tested against 5 strains which did not have any alterations of either GyrA or ParC. Based on the MIC90s, DU-6859a exhibited 8- to 32-fold greater activity than the currently available fluoroquinolones against strains having alterations in DNA gyrase and topoisomerase IV.