Moxifloxacin activity against clinical isolates compared with the activity of ciprofloxacin.

The activity of moxifloxacin, a new 8-methoxyquinolone, was compared in vitro with the activity of ciprofloxacin against clinical strains isolated from various sites of infection. The mode MIC values of moxifloxacin were superior to those of ciprofloxacin against Streptococcus pneumoniae, methicillin-susceptible and -resistant Staphylococcus aureus, Enterococcus spp., Escherichia coli and Acinetobacter spp., while ciprofloxacin was more active against Klebsiella pneumoniae and Pseudomonas spp. Both antibiotics had similar activity against Haemophilus influenzae, Moraxella catarrhalis and Enterobacter spp.

The influence of urine on the in vitro antimicrobial activity of various antibiotics against different Escherichia coli phenotypes.

BACKGROUND: The influence of urine on the in vitro activities of various antibiotics used in the therapy of urinary tract infections was assessed by the microbroth dilution method in this study. METHODS: Thirty Escherichia coli strains were used: 10 E. coli strains susceptible to ampicillin, 10 strains resistant to ampicillin and ampicillin+sulbactam and ten extended spectrum beta-lactamase producer strains. The minimum inhibitory concentrations (MICs) of ampicillin, ampicillin + sulbactam, cephalothin, cefuroxime, ceftriaxone, amikacin, ciprofloxacin, sulfamethoxazole and trimethoprim were performed parallel in Mueller-Hinton broth and human urine by the microbroth dilution method. RESULTS: The MIC(90) of all antibiotics except cephalothin were higher in the urine. MICs performed in the urine were found significantly higher than those performed in broth. CONCLUSIONS: This study demonstrated that MICs of antibiotics are influenced by the human urine and that MICs of some antibiotics used in the treatment of urinary tract infections may be overestimated by the standard antibiotic testing methods.