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Influence of anidulafungin on different Candida species in a continuous flow culture system

Abstract number: P2169

Bernhardt H., Knoke M., Schwesinger G., Gloeckner A., Bufler J., Czaika V., Ludwig K., Bernhardt J.

Objectives: We investigated the antifungal effect of anidulafungin (ANID) on biofilms and MIC values of different Candida species in a miniature flow cell system.

Methods: Strains of C. albicans (Ca), C. glabrata (Cg), C. krusei (Ck), C. parapsilosis (Cp) and C. lusitaniae (Cl) from blood culture isolates were grown in flow cells (0.16 mL). Peptone-yeast extract (0.5%/0.2%) + 50 mM glucose +/- ANID (8 mg/L) was supplied at very low flow rates (1.3 mL/h). Biomass production, glucose metabolism, pH and planktonic CFUs were measured. MIC testing was performed by Etest® on RPMI or Mueller-Hinton methylene blue agar. Morphology of adherent fungal cells was assessed microscopically after staining with lactophenol cotton blue.

Results: For Ca (3 isolates, 5 experiments) we found a strong decrease of biomass production, elevated concentrations of glucose and an increase in pH after continuous input of ANID. MICs of baseline strains were 0.003–0.004 mg/L. The same MIC values were found on day 2, 4 and 5. After 5 d sometimes, the biofilm did not show any growth. In one experiment, an increase of MIC to 0.75 mg/L was to be seen, but there was no development of resistance (no growth of biofilm on day 7). In 5 experiments with Cg (4 strains) glucose metabolism stopped within 24 h and no biomass remained after 3–4 d. MIC 0.012–0.016 mg/L. Ck biofilm (1 strain, 1 experiment) was most susceptible to ANID (MIC 0.004 mg/L) equally for baseline strain and biofilm. Cp (4 strains, 8 experiments) showed different degrees of susceptibility. In some experiments, we saw small inhibition zones (MIC 4–8 mg/L). In others, we found no inhibition and no production of biofilm under the influence of ANID. Cl (1 strain, 1 experiment) was found to be good susceptible to ANID. The produced biofilm stopped after ANID exposure (MIC 0.023 mg/L).

Conclusion: Under continuous flow conditions, the strains of Ca, Cg and Ck were most susceptible to ANID as described for static conditions. Cl was also very susceptible. Cp showed different degrees of susceptibility.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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