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Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray
Published on: April 25, 2014
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Predicting extensively drug-resistant Mycobacterium tuberculosis phenotypes with genetic mutations.
Timothy C Rodwell1, Faramarz Valafar, James Douglas
1Department of Medicine, University of California San Diego, San Diego, California, USA.
Journal of Clinical Microbiology
|December 20, 2013
Summary
Molecular diagnostic methods accurately detect multidrug-/extensively drug-resistant tuberculosis (M/XDR TB). Specific mutations in Mycobacterium tuberculosis genes serve as reliable markers for rapid M/XDR TB diagnosis.
Area of Science:
- Microbiology
- Genetics
- Molecular Diagnostics
Background:
- Multidrug-/extensively drug-resistant tuberculosis (M/XDR TB) poses a significant global health challenge.
- Rapid and accurate diagnostic methods are crucial for effective M/XDR TB treatment and control.
- Current large-scale studies on mutation markers for M/XDR TB are limited.
Purpose of the Study:
- To evaluate the sensitivity and specificity of mutations in Mycobacterium tuberculosis as markers for M/XDR TB.
- To inform the development of rapid molecular diagnostic methods for M/XDR TB.
- To analyze a large collection of M/XDR TB isolates from high-prevalence regions.
Main Methods:
- Analysis of 417 Mycobacterium tuberculosis isolates from India, Moldova, the Philippines, and South Africa.
- Standardized phenotypic drug susceptibility testing (DST) for isoniazid (INH), rifampin (RIF), moxifloxacin (MOX), ofloxacin (OFX), amikacin (AMK), kanamycin (KAN), and capreomycin (CAP).
- Sanger sequencing of eight genes (katG, inhA, rpoB, gyrA, gyrB, rrs, eis, and tlyA) to identify resistance-conferring mutations.
Main Results:
- Identified specific single nucleotide polymorphisms (SNPs) with high sensitivity and specificity for detecting resistance to various TB drugs.
- Four SNPs in katG/inhA showed 96% sensitivity and 97-100% specificity for isoniazid resistance.
- Eleven SNPs in rpoB demonstrated 98% sensitivity for rifampin resistance.
- Combined SNPs in six genes predicted clinically relevant XDR-TB phenotypes with 90-98% sensitivity and nearly 100% specificity.
Conclusions:
- Specific mutations in Mycobacterium tuberculosis genes are highly accurate markers for detecting drug resistance.
- Molecular diagnostic methods based on these mutations can facilitate rapid detection of M/XDR TB.
- The findings support the development of advanced molecular diagnostics for improved M/XDR TB management.
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