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Published on: September 3, 2012
Rapid and accurate identification of nontuberculous mycobacteria (NTM) by MALDI-TOF MS using a modified extraction
Asmita Salvi1, Shaoli Basu1, Anjali Shetty1
1Microbiology Section, Department of Laboratory Medicine, P.D. Hinduja National Hospital and Medical Research Centre, Mumbai, India.
Indian Journal of Medical Microbiology
|July 3, 2026
Summary
Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF MS) offers rapid and accurate identification of nontuberculous mycobacteria (NTM). This optimized method provides timely results, aiding clinical decisions in diagnostic laboratories.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Mass Spectrometry
Background:
- Accurate identification of nontuberculous mycobacteria (NTM) is crucial for effective treatment and antimicrobial susceptibility determination.
- Treatment strategies and outcomes for NTM infections vary significantly by species.
- Rapid diagnostics are needed in tertiary care settings, particularly in regions like Mumbai, India.
Purpose of the Study:
- To evaluate the performance of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF MS) for NTM species identification.
- To assess a modified protein extraction protocol for enhanced MALDI-TOF MS accuracy.
- To compare MALDI-TOF MS results with a molecular method, Line Probe Assay (LPA).
Main Methods:
- Analysis of 110 consecutive clinical NTM isolates (73 rapid growers, 37 slow growers).
- Standardized protein extraction using a bead-based method with 70% alcohol inactivation.
- Comparison of MALDI-TOF MS identification with GenoType® Mycobacterium CM assay (LPA).
Main Results:
- MALDI-TOF MS achieved 98.18% correct identification of NTM isolates.
- High concordance (92.72%) was observed between MALDI-TOF MS and LPA.
- MALDI-TOF MS provided species-level identification for six isolates initially reported as Mycobacterium spp. by LPA.
- The MALDI-TOF MS workflow yielded results in 90-120 minutes, significantly faster than LPA (24-48 hours).
Conclusions:
- Optimized MALDI-TOF MS is a rapid, accurate, and reproducible method for NTM identification.
- This technique supports timely clinical decision-making for NTM infections.
- MALDI-TOF MS presents a practical and efficient alternative to molecular assays in diagnostic laboratories.
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