Activity of amphotericin B, caspofungin and anidulafungin on planktonic and biofilm Candida spp. by microcalorimetry

Ref ID: 17754

Author:

E. Maiolo*, U. Furustrand Tafin, D. Sanglard, A. Trampuz

Author address:

(Lausanne,
CH)

Full conference title:

22nd European Congress of Clinical Microbiology and Infectious Diseases

Abstract:

Objectives: Candida biofilms are difficult to treat due to reduced
susceptibility in biofilm. We compared the activity of amphothericin B
(AMPB) and two echinocandins, caspofungin (CAS) and anidulafungin
(AFG), against planktonic and biofilm Candida spp. using
microcalorimetry, a real-time and highly sensitive assay for
measurement of growth-related heat production.
Methods: C. albicans (ATCC 90028), C. krusei (ATCC 6258) and C.
glabrata (DSY 562) were tested. Minimal inhibitory concentration
(MIC) was determined by microbroth dilution according to the
EUCAST guidelines (EDef 7.1) and confirmed by E-test.
Microcalorimetry was performed using an isothermal calorimeter
(TAM III, TA Instruments) at 37C in sealed glass ampoules
containing 3 mL RPMI. Planktonic Candida species (5 · 105 CFU)
were added to RPMI containing serial dilution of AMPB, CAS or AFG
(0.125-512 lg/mL). Candida biofilm was formed on porous glass
beads (diameter 4 mm, pore size 60 lm) and incubated for 24 hour at
37C in RPMI. Beads were washed and incubated for 24 hour in RPMI
containing serial dilution of AMPB, CAS or AFG (0.5-1024 lg/mL).
Beads were then washed and placed in 3 mL of RPMI into the
calorimeter to quantify recovering yeasts. The minimal heat inhibitory
concentration (MHIC) was defined as the lowest antifungal
concentration reducing the heat-flow peak by “¡50%.
Results: The MICs for tested Candida spp. ranged from 0.5-2 lg/mL
for AMPB, 0.125-0.5 lg/mL for CAS and 0.03-0.015 lg/mL for
AFG. Table shows MHICs (in lg/mL) for planktonic and biofilm
Candida. Compared to planktonic counterparts, the activity of AMPB
was significantly reduced against Candida biofilms (MHIC “¡32 lg/
mL). CAS showed antibiofilm activity against C. albicans and C.

Abstract Number: NULL

Conference Year: 2012

Link to conference website: NULL

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