Guidance for using diagnostic algorithm for pulmonary tuberculosis — MSF Tuberculosis

What this guideline says

GMJ summary

This MSF guidance section provides a step-by-step diagnostic algorithm for pulmonary tuberculosis (PTB) in adolescents (≥10 years) and adults presenting with symptoms. It emphasises the use of rapid molecular tests (RMTs) such as Xpert MTB/RIF and Xpert MTB/RIF Ultra as primary diagnostic tools, with specific guidance on when to repeat testing and how to interpret indeterminate or trace results.

The guidance distinguishes diagnostic approaches for people living with HIV (who should receive LF-LAM testing in addition to RMT) from those without HIV infection. It provides clear criteria for when second tests are needed, including error results, indeterminate rifampicin resistance, and negative results with high clinical suspicion. For Xpert MTB/RIF Ultra ‘trace’ results, specific interpretation rules apply based on HIV status, history of previous TB, and specimen type.

For patients with multidrug-resistant or rifampicin-resistant tuberculosis (MDR/RR-TB), the guidance mandates phenotypic drug susceptibility testing (pDST) and next-generation sequencing (NGS) when available to detect resistance to bedaquiline, linezolid and other drugs not covered by rapid molecular tests. The guidance also covers the role of chest X-ray findings and provides alternatives when RMTs are not immediately available.

Key points

For clinicians — doses and thresholds as stated in the guideline

1. Adolescents are defined as patients aged 10 years or more for the purposes of this diagnostic algorithm.
2. In people living with HIV, PTB symptoms include any of: current cough, fever, weight loss or night sweats; without HIV: cough for more than 2 weeks, haemoptysis, unexplained weight loss, night sweats or clinical suspicion.
3. LF-LAM should only be performed in patients with HIV infection; an RMT must also be performed regardless of LF-LAM result.
4. Repeat Xpert MTB/RIF on a new specimen if the result is error/invalid/no result, rifampicin resistance indeterminate, MTB not detected with high clinical suspicion, or rifampicin resistance detected in a low-risk patient.
5. For Xpert MTB/RIF Ultra 'trace' results: consider positive in HIV-positive patients, children and extrapulmonary specimens (do not repeat); cannot interpret in adults with TB history in previous 5 years (perform culture instead).
6. If Xpert MTB/RIF Ultra shows 'trace' on two specimens, do not perform Xpert MTB/XDR; use pDST or another gDST instead.
7. Chest X-ray findings suggestive of PTB include infiltrates in upper lobes and superior segments of lower lobes, cavities, consolidations, mediastinal/hilar lymphadenopathy, and miliary pattern.
8. Perform pDST and NGS (if available) in all MDR/RR-TB patients to detect resistance to bedaquiline, linezolid and other drugs not tested by RMTs.

Clinical symptoms triggering PTB diagnostic algorithm

Table extracted from the guideline

Source: Médecins Sans Frontières, Guidance for using diagnostic algorithm for pulmonary tuberculosis — MSF Tuberculosis. Reproduced in summary form.

From the guideline

Verbatim

“A pDST and, if available, a next generation sequencing (NGS) should be performed in all patients with MDR/RR-TB to detect potential resistance to bedaquiline, linezolid and other drugs not tested by RMTs.”

Editor’s perspective

Why this matters for Georgia and the region

Applicability

Georgia and the South Caucasus

Questions this guideline answers

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