In Vitro Activity of Levofloxacin against Penicillin-Resistant Streptococcus pneumoniae
Bor-Shen Hu, MD
Section of Infectious Diseases, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
The prevalence of resistant pneumococci has increased worldwide and resistant strains are the leading isolates in some areas. The goal of this study was to compare the in vitro activity of levofloxacin against penicillin-resistant Streptococcus pneumoniae with those of ofloxacin, norfloxacin, enoxacin, ciprofloxacin and vancomycin. A total of 76 clinical isolates were included. MICs were determined by the methods of the National Committee for Clinical Laboratory Standards, using agar dilution. The MIC90 of levofloxacin was 1µg/ml. Levofloxacin was twofold more potent than ofloxacin and fourfold more potent than ciprofloxacin. All isolates were susceptible to levofloxacin and vancomycin. Levofloxacin was found to be the most potent fluoroquinolone in our study, followed by ofloxacin, ciprofloxacin, norfloxacin and enoxacin.