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Effect of disinfectants and caspofungin against planktonic and sessile cells of Candida spp.

Abstract number: 1733_126

Tobudic S., Kratzer C., Graninger W., Georgopoulos A.

Objectives: The aim of this study was to evaluate the activity of 3 different disinfectants chlorhexidine digluconate, Akacid plus® and hydrogen peroxide compared to the antifungal caspofungin against planktonic and sessile cells of Candida spp.

Methods: As test strains 40 clinical isolates of Candida spp. including C. albicans, C. krusei and C. tropicalis were used. The activity of active substances was determined against planktonic cells according to CLSI guidelines for antifungals using broth microdilution method. For antifungal susceptibility testing of sessile cells, isolates were incubated overnight in yeast peptone dextrose resuspended in RPMI 1640 to a cellular density equivalent to 1.0×106 CFU/mL. Cells were grown for 48 h in 96-well-microtiter plates, and then treated with 100 ml of Akacid plus®, chlorhexidine and hydrogen peroxide at a final concentration of 0.25, 0.5, 1, 2 and 4% compared to caspofungin at a concentration of 64, 128, 256 and 512 mg/l for 48°C at 35°C. The cells were fixed and stained with crystal violet. The mean optical density was used for quantification using a routine microtiter-plate-reader at 490 nm. Additionally, fungal growth following antimicrobial treatment was examined.

Results: MICs of Akacid plus® and caspofungin against planktonic cells of Candida spp. were comparable and reached MIC values of 0.03–8 mg/l, whereas MICs of chlorhexidine and hydrogen peroxide ranged from 16 to 32 mg/l and from 128 to 256 mg/l. Low concentrations of caspofungin at 64 mg/l caused a 62% reduction of the sessile cells of Candida spp. Treatment with 0.25% chlorhexidine and Akacid plus® led to reduction of the sessile cells in 59 and 74%, whereas hydrogen peroxide showed no effect.. No viable cells of Candida spp. were detected in biofilms treated with 0.25% Akacid plus® and chlorhexidine or 0.1% caspofungin.

Conclusion: Caspofungin and cationic antimicrobials showed high activity against sessile and planktonic cells of Candida spp., whereas hydrogen peroxide was found to be ineffective.

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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