Contribution of topoisomerase IV and DNA gyrase mutations in Streptococcus pneumoniae to resistance to novel fluoroquinolones.

ABSTRACT: In this study, we assessed the activity of ciprofloxacin, levofloxacin, sparfloxacin, and trovafloxacin against clinical isolates of Streptococcus pneumoniae that were resistant to the less-recently developed fluoroquinolones by using defined amino acid substitutions in DNA gyrase and topoisomerase IV. The molecular basis for resistance was assessed by using mutants selected with trovafloxacin, ciprofloxacin, and levofloxacin in vitro. This demonstrated that the primary target of trovafloxacin in S. pneumoniae is the ParC subunit of DNA topoisomerase IV, similar to most other fluoroquinolones. However, first-step mutants bearing the Ser79-->Phe/Tyr substitution in topoisomerase IV subunit ParC were susceptible to trovafloxacin with a minimum inhibitory concentration of 0.25 microg/ml, and

SUBMITTER: Pestova E 

PROVIDER: S-EPMC89404 | biostudies-literature | 1999 Aug

REPOSITORIES: biostudies-literature