Multicentre in-vitro evaluation of the susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis to ciprofloxacin, clarithromycin, co-amoxiclav and sparfloxacin.

Seven laboratories, including a reference laboratory, tested the susceptibility of Moraxella catarrhalis, Streptococcus pneumoniae and Haemophilus influenzae strains to ciprofloxacin, clarithromycin, co-amoxiclav and sparfloxacin with the Etest. A total of 976 strains were collected. The results with ciprofloxacin and sparfloxacin were consistent for all laboratories, while those with clarithromycin and co-amoxiclav were not. The agreement between Etest MICs and broth microdilution was: ciprofloxacin and sparfloxacin, >95%; clarithromycin for all species, 71-85%; co-amoxiclav for H. influenzae, 31%. MIC90 values (broth dilution, mg/L) for M. catarrhalis, S. pneumoniae and H. influenzae were: sparfloxacin, 0.06, 0.5, 0.03; ciprofloxacin, 0.12, 2.0, 0.03; co-amoxiclav, 0.25, 0.25, 0.25; clarithromycin 0.25, 0.25 and 16.