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A novel liquid media mycobacteria extraction method for MALDI-TOF MS identification using VITEK® MS
Erik Moreno1, Eric Miller1, Elizabeth Miller1
1bioMérieux Inc., R&D Microbiology, Durham, NC, USA.
Journal of Microbiological Methods
|November 22, 2017
Summary
A new, low-cost method rapidly identifies mycobacteria directly from liquid cultures using VITEK® MS in under 45 minutes. This validated technique offers safe, reliable, and reproducible results for diagnosing mycobacterial infections.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Mass Spectrometry
Background:
- Accurate and rapid identification of mycobacteria is crucial for timely diagnosis and treatment of mycobacterial infections.
- Existing methods for mycobacterial identification from liquid cultures can be time-consuming or require specialized equipment.
- There is a need for a cost-effective and direct identification method from positive liquid culture media.
Purpose of the Study:
- To develop and validate a novel, low-cost, and rapid method for direct identification of mycobacteria from positive liquid cultures.
- To assess the performance of the VITEK® MS system for mycobacterial identification using the developed protocol.
- To ensure the method is safe, reproducible, and compatible with commonly used automated liquid culture systems.
Main Methods:
- A protocol was developed involving mechanical disruption of mycobacteria from a positive liquid culture using glass beads and ethanol.
- Inactivated mycobacterial extracts were prepared using formic acid and acetonitrile.
- Identification was performed using VITEK® MS, with protein extracts deposited on target slides and matrix added.
Main Results:
- The method achieved a 98.8% correct identification rate in a seeded study of 251 samples from various automated culture systems.
- Reproducibility studies demonstrated an overall correct identification rate of 98.9% across multiple reagent lots, technicians, and days.
- The method proved to be safe, consistent, and compatible with BacT/ALERT® MP, BACTEC MGIT™ 960, and VersaTREK® Myco systems.
Conclusions:
- The described VITEK® MS-based method provides a rapid, cost-effective, and reliable means for direct mycobacterial identification from positive liquid cultures.
- This validated protocol offers a safe and reproducible workflow, enhancing clinical diagnostic capabilities for mycobacterial infections.
- The method's compatibility with major liquid culture systems makes it adaptable for routine clinical laboratory use.
