From the Guidelines
The primary methods for monitoring tuberculosis (TB) treatment include smear microscopy and culture, although these tools have significant limitations, such as requiring sputum samples and taking weeks to obtain results 1.
Monitoring Methods
- Smear microscopy: cannot differentiate viable from non-viable bacteria and relies on sputum samples 1
- Culture: takes weeks to obtain results and also relies on sputum samples 1
Limitations of Current Methods
These methods are under-implemented as TB treatment monitoring tools due to their limitations, including the difficulty of collecting sputum samples from certain patients, such as those with HIV or children 1.
Need for New Monitoring Tools
There is a growing need for new TB treatment monitoring tools that can guide treatment during the course of therapy, rather than just testing for a cure at the end of treatment 1.
Potential New Tools
Research is ongoing to develop new tools, including biomarkers and multi-marker biosignatures, that can accurately predict treatment outcomes and guide treatment decisions 1.
Definitions and Terminology
Key terms in this area include treatment monitoring tool, bacteriologic conversion, treatment failure, and relapse, which are defined in Table 1 of 1.
From the Research
Methods for Monitoring Tuberculosis (TB)
The methods for monitoring TB can be categorized into several areas, including:
- Molecular methods for diagnosis and monitoring of multidrug-resistant tuberculosis (MDR-TB) treatment, such as Xpert® MTB/RIF, GenoType MTBDRplus, and DNA sequencers 2
- Biomarkers for risk assessment, diagnosis of active disease, and monitoring of treatment response, including genetic signatures, metabolites, and RNA-based transcriptomic signatures 3
- Modalities to monitor treatment response in TB, including assessment of treatment efficacy, disease activity, cure, and relapse 4
- Molecular technologies and assays for treatment response and outcome, which can serve as substitutes for current culture-based readouts 5
- Biomarkers for diagnosing and therapeutic monitoring of TB, including molecular, immunological, and novel methodologies 6
Molecular Methods
Molecular methods, such as Xpert® MTB/RIF and GenoType MTBDRplus, can accurately guide effective treatment regimens and quantify mycobactericidal impact 2. These methods have inherent advantages compared to the current standard of care but also carry important limitations to implementation and/or scale-up.
Biomarkers
Biomarkers, such as genetic signatures and metabolites, show potential in predicting the progression from TB infection to active TB 3. RNA-based transcriptomic signatures can provide higher diagnostic accuracy than traditional methods and effectively differentiate active TB from other diseases and infections. Emerging biomarkers focus on bacterial burden and host response, offering more precise and timely assessments of treatment efficacy.
Treatment Response Monitoring
Monitoring treatment response in TB is crucial, and various methods are available, including: