Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus
isolates were exposed to subinhibitory MICs of ciprofloxacin, sparfloxacin
, gatifloxacin, moxifloxacin, clinafloxacin, and gemifloxacin during a 10-d
ay period. Subculturing led to resistance development, regardless of the in
itial potencies of the quinolones. None of the quinolones was associated wi
th a significantly slower rate of resistance development.