Performance Comparison of GeneXpert MTB/RIF and ProbeTec ET Tests for Rapid Molecular Diagnosis of Extrapulmonary Tuberculosis in a Low TB/MDR-TB Incidence Country

Diagnosis of tuberculous pleural effusion in a tertiary care hospital of central India: The role of xpert Mycobacterium tuberculosis/rifampicin

Background

In India, 15%-20% of tuberculosis (TB) cases are categorized as extra-pulmonary TB, and tuberculous pleural effusion (TPE) is the second-most common type after tuberculous lymphadenitis. However, the paucibacillary nature of TPE makes its diagnosis challenging. As a result, relying on empirical anti-TB treatment (ATT) based on clinical diagnosis becomes necessary for achieving the best possible diagnostic outcome. The study aims to determine the diagnostic utility of Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) for the detection of TB in TPE in high incidence setting of Central India.

Methods

The study enrolled 321 patients who had exudative pleural effusion detected through radiological testing and were suspected of having TB. The medical procedure of thoracentesis was conducted to collect the pleural fluid, which was then subjected to both the Ziehl-Neelsen staining and Xpert MTB/RIF test. The patients who showed improvement after receiving anti-tuberculosis treatment (ATT) were considered the composite reference standard.

Results

The sensitivity of smear microscopy was found to be 10.19%, while that of the Xpert MTB/RIF method was 25.93% when compared to the composite reference standard. The accuracy of clinical diagnosis was measured using receiver operating characteristics based on clinical symptoms, and it was found to be 0.858 (area under the curve).

Conclusions

The study shows that Xpert MTB/RIF has significant value in diagnosing TPE, despite its low sensitivity of 25.93%. Clinical diagnosis based on symptoms was relatively accurate, but relying on symptoms alone is not enough. Using multiple diagnostic tools, including Xpert MTB/RIF, is crucial for accurate diagnosis. Xpert MTB/RIF has excellent specificity and can detect RIF resistance. Its quick results make it useful in situations where a rapid diagnosis is necessary. While it should not be the only diagnostic tool, it has a valuable role in diagnosing TPE.

The Usefulness of Bronchoscopy in the Diagnosis of Mycobacterium tuberculosis Complex Species Infection

BACKGROUND: Pulmonary tuberculosis is an active chronic infection of the lungs. It is still a public health problem globally caused by the Mycobacterium tuberculosis Complex (MTBC). These species are difficult to determine only by conventional tests. The clinical manifestations are almost similar between the strains and cause diagnosis delays. Prolonged and intolerable MTBC therapy inhibits infection control. AIM: This study aims to evaluate the usefulness of bronchoscopy in diagnosing the MTBC species infection. METHODS: This study recruited patients with difficulty expectorating sputum. Pulmonary tuberculosis was diagnosed with the Xpert MTB/RIF assay. This study assessed sputum Acid Fast Bacilli (AFB) staining, chest X-rays with active pulmonary tuberculosis, characteristics of Bronchoalveolar lavage (BAL), and bronchoscopic findings based on the Chung classification. The BAL of polymerase chain reaction analysis using RD9 and TbD1 primers to determine MTBC species. RESULTS: Out of the 30 cases, M. tuberculosis and Mycobacterium bovis 24 (80.0%) and 6 (20.0%) were identified in BAL fluid. There were 12 cases (40.0%) with AFB sputum test, and 25 (83.3%) of the Xpert MTB/RIF detected tuberculosis cases. All chest X-rays showed infiltrated and 22 (73.3%) pulmonary ectasis. There was a significant difference in MTBC species between sputum and BAL fluid (p < 0.05). The ulcerative type of bronchoscopy findings was significantly different in MTBC species (p < 0.05) and there was no macroscopic BAL fluid difference (p > 0.05). CONCLUSIONS: Bronchoscopy is a specimen collection technique that is beneficial in determining the diagnosis of MTBC. Analysis of BAL with molecular methods contributes to identifying MTBC species quickly and accurately.

The Value of GeneXpert MTB/RIF for Detection in Tuberculosis: A Bibliometrics-Based Analysis and Review

With the continuous development of medical science and technology, especially with the advent of the era of precision diagnosis and treatment, molecular biology detection technology is widely valued and applied as an aid to early diagnosis of tuberculosis. The GeneXpert Mycobacterium tuberculosis Branching (MTB) technology is a suite of semi-nested real-time fluorescent quantitative PCR in vitro diagnostic technologies developed by Cepheid Inc. It targets the rifampicin resistance gene, rpoB, and can detect both MTB and resistance to rifampicin within 2 h. This review analyzed the papers related to GeneXpert using bibliometric software CiteSpace and Bibliometrix. A total of 151 articles were analyzed, spanning from 2011 to 2021. This bibliometrics-based review summarizes the history of the development of GeneXpert in tuberculosis diagnosis and its current status. Contributions of different countries to the topic, journal analysis, key paper analysis, and clustering of keywords were used to analyze this topic.