Intracellular penetration and activity of the new fluoroquinolone UB-8902 in human polymorphonuclear leukocytes
Abstract number: P552
Ballesta S., García I., Sánchez-Céspedez J., Vila J., Pascual A.
Background: UB-8902, a 7-(4-methyl)-piperazine ciprofloxacin derivative, is a new fluorquinolone that shows higher in vitro activity than ciprofloxacin. The uptake of UB-8902 by human polymorphonuclear leukocytes (PMN) and its intracellular activity against isogenic strains of Staphylococcus aureus with sequential mutations in gyrA and/or parC genes were also evaluated.
Methods: Uptake of UB-8902 by PMNs was determined by a fluorometric assay. The effect of cell viability, environmental conditions, metabolic inhibitors, potential competitive substrates and PMN-stimuli on intracellular uptake was also studied. The intracellular activity was determined by incubation of PMN containing intracellular bacteria in the presence of UB-8902. Wild-type and mutant S. aureus with mutation in gyrA and/or parC were used for the killing assays.
Results: UB-8902 uptake by PMN was rapid and saturable at extracellular concentrations higher than 10 mg/L. At extracellular concentrations of 2 mg/L, the cellular to extracellular concentration (C/E) ratio was 6.5 ±0.8. The efflux of UB-8902 from PMN was also a rapid process. The intracellular penetration of UB-8902 was slightly increased when dead cells were used (7.6±1.3 versus control 6.5±0.8) and unaffected at 4°C (C/E ratio 6.3±1.5). The uptake of UB-8902 by PMN was significatly affected by the extracellular pH (intracellular penetration decreased at basic pH and increased at acid pH). Sodium cyanide, an inhibitor of mitochondrial oxidative metabolism, significantly impaired intracellular penetration of UB-8902 (C/E ratio: 3.3±1.4). The ingestion of opsonised zymosan significantly increased the levels of PMN-associated UB-8902 (C/E ratio: 9.9± 1.3). Neither cell stimulation by phorbol myristate acetate (PMA) nor ingestion of opsonised Staphylococcus aureus, modified the uptake (C/E ratio:7.1±0.8 and 7.0±1.0 respectively). At extracellular concentrations evaluated, 0.125, 1 y 5 mg/L, UB-8902 significantly decreased the intracellular survival of wild-type S. aureus. For the mutant strains, UB-8902 only showed significant intracellular activity at extracellular concentration higher than 1 mg/L.
Conclusions: UB-8902 penetrates into PMN, reaching high intracellular concentrations and it remains active intracellularly against S. aureus.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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