Evaluation of the bactericidal activity of temafloxacin

Although the fluoroquinolones share many properties, these agents differ in their ability to kill the same bacterial strain. The bactericidal activity of temafloxacin against a number of pathogens has been compared with that of other fluoroquinolones by determination of minimal bactericidal concentration, time-kill kinetics, and postantibiotic effect. Studies have demonstrated that temafloxacin has equivalent or superior ability to kill when compared with other fluoroquinolones. Temafloxacin, ciprofloxacin, and PD 117558 were more active than other fluoroquinolones against Mycobacterium avium complex, with 90% minimal bactericidal concentrations (MBC90S; 8-16 micrograms/mL) four- to eightfold greater than 90% minimal inhibitory concentrations (MIC90S; 2 micrograms/mL). Against Chlamydia trachomatis the MIC90 and MBC90 of temafloxacin were both 0.25 microgram/mL; ciprofloxacin was less active (MBC90 twice the MIC90), and norfloxacin was least active. Temafloxacin demonstrated more rapid killing kinetics than did ciprofloxacin or ofloxacin at all concentrations tested against Streptococcus pyogenes. Findings were similar against Streptococcus pneumoniae at antibiotic concentrations of 1-2 micrograms/mL. Similar time-kill curves against Escherichia coli were observed for temafloxacin, ciprofloxacin, and difloxacin. Time-kill kinetics of temafloxacin against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) were superior to those of ciprofloxacin and ofloxacin. Postantibiotic effect with temafloxacin against Legionella pneumophila showed a considerable delay in regrowth, and temafloxacin delayed regrowth of MRSA and MSSA to a greater extent than did ciprofloxacin or ofloxacin. By the three methods used in the studies to assess bactericidal activity that are currently published, temafloxacin had equivalent or superior activity to the comparative fluoroquinolones tested. Other organisms remain to be tested and the significance of these findings determined in clinical studies.