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Influence of newer fluoroquinolones on phagocytosis and killing of Candida albicans by human polymorphonuclear neutrophils

Abstract number: 1733_1562

Mörler C., Grüger T., Brandenburg K., Nidermajer S., Schnitzler N., Horrè R., Zündorf J.

Objectives: The function of the Polymorphonuclear Neutrophils (PMN) is of high relevance for the prognosis of antibiotic treated patients. Especially phagocytosis and intracellular killing of pathogenic microorganisms have large impact on the outcome of infections. Many antiinfectives have been shown to influence the function of these cells. The aim of this project was to achieve more detailed information about the influence on phagocytosis and intracellular killing of pathogenic microorganisms such as Candida albicans by newer fluoroquinolones.

Methods: We analysed the effect of several fluoroquinolones on phagocytosis and killing of C. albicans by human PMN. C. albicans was chosen as pathogen for its naturally high resistance to fluoroquinolones thereby excluding direct influence of the substances tested on the vitality of the microorganism.

Whole blood samples from healthy volunteers were incubated with the fluoroquinolones in concentrations ranging from 0.5 mg/mL up to 1500 mg/mL and compared to a drug-free control. Fluorescent-labeled C. albicans cells were then added in a C. albicans/PMN ratio of at least 2.5:1. Phagocytosis was stopped after incubation of 5, 15, 30 and 60 minutes and the samples were measured by flow cytometry.

Intracellular Killing of C. albicans was analysed after phagocytosis (4 h) by plate counting the washed probes.

Results: Tested fluoroquinolones in clinical relevant concentrations (0.5, 5.0, and 100 mg/mL) did not have significant influence on phagocytosis and killing of C. albicans by human PMN. In contrast higher concentrations (1500 mg/mL) of some newer fluoroquinolones do have negative impact on phagocytosis without influencing viability of PMNs.

Conclusion: Newer fluoroquinolones in clinical relevant concentrations do not affect phagocytosis and killing of Candida albicans. Thus, antiinfective therapy with newer fluoroquinolones seems to have no impact on the main human defence mechanism against the opportunistic pathogenic fungus C. albicans.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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