Longitudinally Tracking Fluoroquinolone Resistance and Its Determinants in Penicillin-Susceptible and -Nonsusceptible Streptococcus pneumoniae Isolates in Hong Kong, 2000 to 2005

Of 1,388 Streptococcus pneumoniae isolates collected from 2000 to 2005, 10.5% had a ciprofloxacin MIC of >/=4.0 mug/ml and 1.6% (range, 0.8% to 4.3% per year) had a levofloxacin MIC of >/=4.0 mug/ml. Molecular characterization indicated that fluoroquinolone resistance occurred independently in our prevalent Spain(23F)-1 clone, expressing serotypes 23F, 19F, and 14. Rates of resistance to levofloxacin in S. pneumoniae have remained stable at a Hong Kong hospital.