Activity of CP 99,219 (trovafloxacin), clinafloxacin, ciprofloxacin, sparfloxacin, lomefloxacin and cefuroxime against 4 penicillin-susceptible, 2 penicillin-intermediate and 4 penicillin-resistant pneumococci was tested by MIC and time-kill methodology. Bacteriostatic values for all three groups did not differ significantly with all compounds tested except cefuroxime, and were lowest for trovafloxacin and clinafloxacin, followed by sparfloxacin, ciprofloxacin and lomefloxacin; cefuroxime yielded values which increased in line with those of penicillin G. The test compounds were bactericidal (i.e. they reduced original counts by > or = 3 log10 cfu/mL at one dilution above bacteriostatic levels) in most cases, though some strains showed slightly greater discrepancies between bacteriostatic and bactericidal levels of all compounds tested. Trovafloxacin, clinafloxacin and sparfloxacin yielded MIC and time-kill results which point to possible efficacy in treatment of penicillin-susceptible and -resistant pneumococcal infections.