Levofloxacin in vitro activity against bacteremic isolates of Streptococcus pneumoniae. Franklin County Pneumonia Study Group.

Levofloxacin had excellent activity in vitro against bacteremic isolates of Streptococcus pneumoniae with 495 (99.2%) of 499 isolates being susceptible. A total of 38 (97.4%) of 39 isolates with minimal inhibitory concentrations > or = 0.12 micrograms/ml of penicillin were susceptible to levofloxacin. There was excellent correlation between the disk diffusion and broth microdilution methods for determining susceptibility. Resistant isolates belonged to four different serotypes. There was no increase in proportion of isolates of S. pneumoniae resistant between 1991 and 1994.