Comparison of two techniques for measurement of in vitro killing kinetics of five antibiotics againstPseudomonas aeruginosa

Abstract

The in vitro activity of ticarcillin, imipenem, gentamicin, amikacin and ciprofloxacin against six Pseudomonas aeruginosa isolates was evaluated by two time-killing curve methods: the conventional broth technique, and another method previously described which employs a transfer filter membrane. The patterns of the killing curves obtained over a 5 h period with the two techniques were similar. In contrast to the results obtained for beta-lactam agents, the reduction of inoculum was great and increased with the concentration for aminoglycosides and ciprofloxacin. After 5 h, regrowth of the six strains tested was observed in broth with all antibiotics, whereas a bactericidal effect was observed over 24 h with the filter membrane method. Further studies are warranted to determine the reasons for this difference.

Nitrite reductase from Pseudomonas aeruginosa induces inflammatory cytokines in cultured respiratory cells

“…Lysis of bacterial cells due to exposure to complement may play an important role in the release of Pseudomonas nitrite reductase in the airway (16), because up to 80% of strains of mucoid P. aeruginosa isolated from patients with CAD are sensitive to low concentrations of normal human serum (30). Another possible mechanism for the release of this enzyme might involve administration of bactericidal antibiotics to these patients (2,20). We have previously reported that a variety of respiratory pathogens induce IL-8 production in the airway of patients with lower respiratory tract infections (31).…”

Bactericidal Effect of Combinations of Antibiotic and Antineoplastic Agents against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>

“…The method of killing curves was chosen since there is doubt as to whether MIC determinations alone are representative of the bactericidal effect of antibiotics [25].…”