The effect of echinocandins on Aspergillus fumigatus investigated by microcultivation of the fungus on porous ceramic and quantitative image analysis

Ref ID: 19186

Author:

C. Ingham, P. Schneeberger

Author address:

Utrecht, Den Bosch, NL

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objectives: Broadly, to create new microbial culture formats based around ceramics that can be used within clinical microbiology. Specifically, to apply such culture methods to understanding how filamentous fungi respond to echinocandins. The echinocandins, a clinically important group of antifungals, are generally considered fungistatic against Aspergillus species (a group which includes members of serious concern as pathogens and the cause of allergies).
Methods: The modes of action of caspofungin and anidulofungin were investigated using culture on porous aluminium oxide (PAO) and within wells of culture chips fabricated from this material. Fluorescence microscopy and scanning electron microscopy was used to image fungal microcolonies. Additionally, PAO supports could be moved between agar plates containing different concentrations of echinocandins to change dosage and to investigate the recovery of fungal microcolonies from these drugs. Culture on PAO combined with microscopy and image analysis (using publically available software) was used for quantitative studies on microcolony growth with the flexibility of adding or removing antifungal agents, dyes, fixatives or osmotic stresses during growth with minimal disturbance of fungal microcolonies.
Results: The PAO was an effective matrix for conidial germination and microcolony growth of A. fumigatus. Anidulafungin and caspofungin reduced but did not halt growth of A. fumigatus at the microcolony level. Both drugs killed individual cells, particularly at concentrations around the MIC, but rarely achieved the death of entire microcolonies. Intact cells showed rapid recovery when the drugs were removed.
Conclusions: The classification of these drugs for A. fumigatus as either fungistatic or fungicidal is simplistic. Microcolony analysis on PAO and culture chips appears to be a valuable tool to investigate the action of antifungal agents. Methods may be devised for screening for greater drug effects at the microcolony level, particularly given cost reductions in imaging systems and improvements in automated image processing.
Reference: Ingham CJ and Schneeberger PM. (2012) Microcolony imaging of Aspergillus fumigatus treated with echinocandins. PLoS ONE e35478.
Figure Legend. Imaging microcolonies of A. fumigatus grown on PAO with echinocandins by SEM. A: Microcolony without drugs. B to E: with echinocandins Arrows indicate lysed hyphal tips.

Abstract Number: P1086

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=165931&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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