The bactericidal activity of gatifloxacin in plasma and urine

OBJECTIVE: To investigate the bactericidal activity of gatifloxacin in serum and urine against relevant pathogens. METHODS: Serum and urine samples obtained in a single rising dose pharmacokinetic study were investigated for bactericidal activity. The doses employed were placebo, and 200, 400, 600 and 800 mg of gatifloxacin. RESULTS: The titers obtained reflected the dose and susceptibility of the pathogen. In serum a titer of greater-than-or-equal1:8 was observed for Escherichia coli for >24 h after 400 mg; for Staphylococcus aureus and Acinetobacter baumanii the titer was greater-than-or-equal1:8 for between 12--24 h after 600 mg; for Serratia marcescens it was greater-than-or-equal1:8 for >12 h following 800 mg; and for Streptococcus pneumoniae it was greater-than-or-equal1:8 for 8 h following 800 mg. In urine, the titers were greater, and for Escherichia coli, Staphylococcus saprophyticus, Proteus mirabilis and Enterococcus faecalis the titer was >1:8 for 12--24 h after 200 mg and for 24--36 h after a 400-mg dose. Pseudomonas aeruginosa demonstrated a titer of >1:8 for 18--24 h following 600 mg. CONCLUSIONS: These data suggest that gatifloxacin should be efficacious for a wide range of systemic and urinary tract infections.