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In vitro activity of caspofungin and anidulafungin against Candida albicans and C. glabrata biofilms

Abstract number: P698

Valentín A., Cantón E., Pemán J., Bosch M., Gobernado M., Martínez J.P.

Objectives: Candidiasis is frequently associated with biofilm formation on indwelling medical devices such as central venous catheters, urinary catheters, heart valves and joint prostheses. Candida spp. biofilms are less susceptible to antifungal agents than planktonic (free-living) cells. The aim of this study was to test the ability of C. albicans and C. glabrata to form biofilms and to determine the activity of caspofungin and anidulafungin against free-living cells and biofilms of both species.

Methods: 16 C. albicans and 23 C. glabrata strains from blood cultures were studied. MICs of planktonic cells were determined following the CLSI M27-A2 document. MIC2 corresponded to the lowest drug concentration that showed a reduction of growth geqslant R: gt-or-equal, slanted 50% compared with the growth control. Biofilms were formed following the method described by Ramage. et al. (1). Antifungal agents at concentrations ranging from 16–0.03 mg/L were added to polystyrene microplates containing Candida biofilms of 24 and 48h of maturation. Antifungal activity against biofilms was assessed by the XTT reduction assay. Sessile MICs (SMICs) 50 and 80 corresponded to the lowest drug dilution that supported an OD leqslant R: less-than-or-eq, slant 50% and leqslant R: less-than-or-eq, slant 20%, respectively compared with control.

Results: 10 C. albicans and 3 C. glabrata developed biofilm (62.5 and 13.04%, respectively). Geometric mean SMIC50s and SMIC80s of caspofungin against C. albicans biofilms of 24/48h of maturation were 0.683/1.878 and geqslant R: gt-or-equal, slanted16/geqslant R: gt-or-equal, slanted16 mg/L, respectively; and against C. glabrata 0.038/0.12 and 0.095/0.12 mg/L, respectively. For anidulafungin, these values were: 0.521/4.52 and geqslant R: gt-or-equal, slanted16/geqslant R: gt-or-equal, slanted16 mg/L against C. albicans and 0.095/0.63 and 0.12/1 mg/L against C. glabrata.

Conclusions:C. albicans produced more biofilm than C. glabrata. Caspofungin and anidulafungin showed activity against C. albicans biofilms of 24h of maturation, but not against those of 48h. Both echinocandins displayed excellent activity against C. glabrata biofilms of 24 and 48h of maturation.

References

1. Ramage G, et al. Standardized method for in vitro antifungal susceptibility testing of Candida albicans Biofims. Antimicrob Agents Chemother 2001; 45:2475–2479.

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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