Effect of growth conditions on antimicrobial activity of DU-6859a and its bactericidal activity determined by the killing curve method

Abstract

The effect of growth conditions on the antibacterial activity of DU-6859a against Staphylococcus auerus, Escherichia coli, and Pseudomonas aeruginosa was compared with those of levofloxacin, sparfloxacin, and ciprofloxacin. This activity was not affected by different media, inoculum size or the addition of human serum, but was decreased under acidic conditions, in human urine, and in the presence of magnesium and ferrous ion, as were the other quinolones tested. Time-kill curve studies demonstrated the bactericidal action of DU-6859a against S. aureus, Streptococcus pneumoniae, E. coli, and P. aeruginosa. Morphological alteration of these bacteria after exposure to DU-6859a also demonstrated its bactericidal activity. The frequency of spontaneous resistance to DU-6859a was less than or equal to those of the reference drugs.

In Vitro and In Vivo Activities of Sitafloxacin against Chlamydia spp

“…The MICs and minimal chlamydiacidal concentrations of sitafloxacin for various species of chlamydia ranged from 0.031 to 0.125 g/ml. Sitafloxacin had an excellent therapeutic effect on experimental Chlamydia psittaci pneumonia and was more potent than tosufloxacin, ofloxacin, and ciproflxacin, although slightly less potent than sparfloxacin.Sitafloxacin is a new fluoroquinolone antimicrobial agent, which has been reported to have a broader spectrum and more potent activity against gram-positive and gram-negative bacteria than currently available quinolones such as ofloxacin, ciprofloxacin, tosufloxacin, and sparfloxacin (11,15,17). In a preliminary study (12), sitafloxacin showed good clinical efficacy against pneumonia and chronic respiratory tract infection.…”

“…Sitafloxacin is a new fluoroquinolone antimicrobial agent, which has been reported to have a broader spectrum and more potent activity against gram-positive and gram-negative bacteria than currently available quinolones such as ofloxacin, ciprofloxacin, tosufloxacin, and sparfloxacin (11,15,17). In a preliminary study (12), sitafloxacin showed good clinical efficacy against pneumonia and chronic respiratory tract infection.…”

Modeling of Transfer Kinetics at the Serum-Cerebrospinal Fluid Barrier in Rabbits with Experimental Meningitis: Application to Grepafloxacin

“…Similarly, saturable protein binding at higher doses should increase and not decrease influx clearance. However, perhaps those rabbits given the lowest grepafloxacin dose developed a more pronounced inflammation of the serum-CSF barrier than those given higher doses, which might have resulted in an increased passive diffusion clearance at the serum-CSF barrier (12,29). If increased inflammation at the lower dose increases average influx clearance, one could expect a decreased efflux clearance (in excess of the influx clearance), as inflammation can reduce bulk flow clearance (see above).…”

Characterization of the Bactericidal Activity of the Natural Diterpene Kaurenoic Acid

“…Antibacterial activity determination in liquid culture was carried out with different serial dilutions of KA in LB broth. Isolation of resistant strains was attempted as described by Tanaka et al [8]. The effect of KA during bacterial growth was studied following change in absorbance when different concentrations of the compound were added to a O.D.…”