A New Filter Based Cultivation Approach for Improving Aspergillus Identification using Matrix-Assisted Laser...

Area of Science:

• Medical Mycology
• Analytical Chemistry
• Clinical Diagnostics

Background:

• Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) is standard for bacterial and yeast identification.
• Identifying filamentous fungi like Aspergillus using MALDI-TOF MS presents methodological challenges.
• Current recommended liquid cultivation methods are time-consuming and labor-intensive.

Purpose of the Study:

• To develop a more reliable, rapid, and less laborious method for identifying Aspergillus species using MALDI-TOF MS.
• To investigate fungal growth on porous surfaces for improved spectral acquisition.
• To create and validate an in-house spectral database for Aspergillus identification.

Main Methods:

• Investigated Aspergillus species growth on polycarbonate membrane filters on Sabouraud dextrose agar.
• Developed an in-house reference spectra database for Aspergillus sections Fumigati and Flavi.
• Validated the method using 50 molecularly identified strains and clinical isolates from Indonesia and Qatar.

Main Results:

• Cultivation on polycarbonate filters yielded reliable mycelial growth and MALDI-TOF MS spectra without sporulation.
• The polycarbonate filter method demonstrated higher correct identification rates (67-76%) compared to liquid cultivation.
• The new method proved superior in accuracy, ease of use, time, cost, and labor intensity.

Conclusions:

• Cultivation of Aspergillus on polycarbonate filters is a more effective MALDI-TOF MS identification method than the standard liquid culture.
• This optimized method offers significant improvements for clinical laboratories identifying Aspergillus species.
• The technique shows potential for broader application in identifying other filamentous fungi.