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Background: Smear microscopy for acid-fast bacilli visualization is important to assess the infectivity rate in patients with pulmonary tuberculosis (PTB), but it has limited sensitivity; hence, it is important to find an alternative strategy. The aim of our study was to compare the fluorescence microscopy grading by Auramine O phenol staining technique of respiratory samples with the cyclic threshold (Ct) values of GeneXpert Ultra (Mycobacterium tuberculosis/rifampicin [MTB/RIF]) and assess the diagnostic efficacy of GeneXpert Ultra (MTB/RIF) compared to microscopy in suspected cases of PTB.
Methods: The study was conducted in the Mycobacteriology Laboratory, Department of Microbiology, in Kasturba Hospital, Manipal. The study was a prospective, single-centered, cross-sectional study. Four hundred and fifty-two respiratory samples were included in the study. An optimal Ct cutoff value for ruling smear-positivity and smear-negativity and the mean Ct cutoff value were calculated. Clinical and radiological data from the requisition forms were assessed. IBM SPSS statistics software version 22 was used. The correlation between GeneXpert Ultra (MTB/RIF) Ct values and smear status was calculated by polychoric correlation. The extended McNemar's test was used to find the association between the variables.
Results: GeneXpert Ultra (MTB/RIF) yielded a higher positivity rate of 22.2% compared to smear microscopy 17.2%. Ct value and smear grading yielded a positive correlation (P = 0.8681; P < 0.05). GeneXpert Ultra (MTB/RIF) yielded nontuberculous mycobacteria in five undetected cases and speciated as Mycobacterium abscessus complex.
Conclusions: Our study confirms the GeneXpert Ultra (MTB/RIF) Ct value levels as a predictor of smear positivity.
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http://dx.doi.org/10.4103/ijmy.ijmy_199_23 | DOI Listing |
BMJ Glob Health
August 2025
Desmond Tutu HIV Centre, University of Cape Town, Rondebosch, South Africa.
Introduction: Effective strategies are essential for early tuberculosis (TB) detection. Reliance on passive case detection, symptom screening and collection of sputum results in delayed or undiagnosed TB, contributing to on-going TB transmission. This study assessed the acceptability of in-home targeted universal TB testing (TUTT) using GeneXpert MTB/RIF Ultra at point-of-care (POC) during household contact investigations (HCIs) and the feasibility of using sputum and tongue swab specimens.
View Article and Find Full Text PDFBackground: Blood-based gene signatures offer potential as a near point-of-care tuberculosis (TB) screening tool. We examined the accuracy of the GeneXpert MTB Host Response (Xpert-HR) cartridge to screen for TB in children.
Methods: We enrolled children under 15 years from The Gambia and Uganda being evaluated for pulmonary TB.
medRxiv
July 2025
Department of Global Health, University of Washington, Seattle, Washington, USA.
Background: Highly sensitive molecular tests, like Xpert Ultra, are reshaping TB diagnosis-detecting paucibacillary TB but sometimes creating uncertainty when they detect DNA in extremely low quantities that may not signal disease. This ambiguity also complicates the evaluation of novel diagnostic strategies. We sought to monitor adults with a 'Trace' result on an Xpert Ultra test to estimate the risk of tuberculosis disease up to 24 months later.
View Article and Find Full Text PDFTrials
August 2025
Mbeya Medical Research Centre, National Institute for Medical Research, Dar Es Salaam, Tanzania.
Background: Tuberculosis (TB) symptom screening and testing using either smear microscopy or GeneXpert MTB/RIF Ultra (Xpert Ultra) have been the mainstay for diagnosing TB disease in case finding. Reliance on symptom-based TB screening results in missed TB cases, and universal TB testing approach might be more suitable to find missing TB cases in high-risk populations. Universal TB testing involves testing for TB disease regardless of TB symptoms in those at risk of TB.
View Article and Find Full Text PDFInt J Tuberc Lung Dis
August 2025
ConnectTB, The Netherlands and Department of Global Health, The Hague;, Department of Global Health, Amsterdam University Medical Centers, Amsterdam, The Netherlands.