Performance of direct detection of Mycobacterium tuberculosis within Mycobacterium tuberculosis complex by routine MALDI-ToF for the diagnosis using species-specific lipid fingerprint
Author(s)
Type
Journal Article
Abstract
Managing tuberculosis cases requires species and drug susceptibility identification, which are limited by the time taken by testing procedures due to slow bacterial growth. Lipid-based matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a promising tool for identifying pathogenic mycobacterial species. This study aims to define and use species-specific lipid profiles of members of the Mycobacterium tuberculosis complex (MTBC) obtained by MALDI-TOF MS, to directly discriminate M. tuberculosis from other members of the MTBC, such as Mycobacterium africanum, Mycobacterium bovis, and M. bovis bacillus Calmette-Guerin (BCG). Reference strains (M. tuberculosis H37Rv, M. africanum, M. bovis, and M. bovis BCG) were grown in Middlebrook 7H11 media (supplemented with 10% oleic acid-albumin-dextrose-catalase growth supplement) and incubated for up to 6 weeks at 37°C to generate the large biomass (~109 bacteria) required for optimization, to assess reproducibility of the assay, and to set the reference lipid database. In clinical use, standard shorter culture periods would be sufficient. A blinded study was then performed using a collection of 46 mycobacterial clinical isolate strains composed of 30 M. tuberculosis, 2 M. africanum, 9 M. bovis BCG, and 5 M. bovis and grown under the same conditions. Cultured mycobacteria were heat-inactivated and loaded onto the matrix-assisted laser desorption target, followed by the addition of the matrix. Acquisition of the data was done using the negative ion mode. Using the species-specific glycolipid, sulfolipids, M. tuberculosis was discriminated within MTBC using the MALDI-TOF process with a sensitivity and specificity of 86.7% (95% confidence interval [CI] 69.3–96.2) and 93.7% (95% CI 69.8–99.8), respectively. Direct detection of M. tuberculosis within the MTBC based on mycobacterial lipid profiling provides a safe and accurate method, based on the detection of the sulfolipids, as a species-specific lipid biomarker of M. tuberculosis.
Date Issued
2025-09-02
Date Acceptance
2025-06-09
Citation
Microbiology Spectrum, 2025, 13 (9)
ISSN
2165-0497
Publisher
American Society for Microbiology
Journal / Book Title
Microbiology Spectrum
Volume
13
Issue
9
Copyright Statement
© 2025 Cheong et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
License URL
Publication Status
Published
Article Number
e00356-25
Date Publish Online
2025-07-22