Use of GeneXpert MTB/RIF on a single pooled sputum specimen to exclude pulmonary tuberculosis among hospital inpatients placed in respiratory isolation

Abstract

Background: Patients with suspected pulmonary tuberculosis (PTB) are usually placed in respiratory isolation awaiting three sputum smear microscopy results for acid-fast bacilli (3AFB). GeneXpert MTB/ RIF (Xpert) on a pooled sample from two sputa may allow for more rapid de-isolation. Objectives: To compare the sensitivity and negative predictive value (NPV) of Xpert performed on a single pooled sputum sample ('pooled Xpert') to 3AFB, in order to exclude PTB in patients placed in respiratory isolation. Methods: Hospital inpatients in respiratory isolation for possible PTB were enrolled prospectively. Three expectorated sputum samples were obtained for smear microscopy. Two of the same samples had 0.5 ml removed from each and pooled for pooled Xpert. The diagnostic accuracy of pooled Xpert and 3AFB were assessed and compared to liquid culture at 8 weeks as the reference standard. Results: Of 56 participants, nine (16.1%) were diagnosed with PTB. Compared to liquid culture, pooled Xpert had a sensitivity of 88.9% (95% confidence interval (CI) 57-99%) and NPV of 97.9% (95% CI 89-99%). 3AFB had a sensitivity of 66.7% (95% CI 35-88%) and NPV of 93.5% (95% CI 83-98%). Conclusions: A single pooled Xpert was non-inferior to 3AFB, with a strong trend towards greater sensitivity and better NPV. These findings support the use of a single pooled Xpert as an effective rapid screening approach for ruling out PTB in low incidence settings. Its value in high incidence settings and optimal combination with smear microscopy and culture warrant further evaluation.

Application of acid-fast staining combined with GeneXpert MTB/RIF in the diagnosis of non-tuberculous mycobacteria pulmonary disease

“…In addition to lung specimens, the ability of GeneXpert MTB/RIF to detect M. tuberculosis in gastric fluid (Tan et al, 2020;van Brusselen et al, 2020), urine (Chen et al, 2020), cerebrospinal fluid (Patel et al, 2020), and biopsy tissue samples (Solanki et al, 2019) has also been verified in previous reports. It was also reported in a previous study that the sensitivity of a single GeneXpert MTB/RIF experiment to diagnose tuberculosis was 88.9% (95% CI 57-99%), which was higher than that of three acid-fast staining experiments (66.7%; 95% CI 35-88%) (Yeong et al, 2020). In this study, the sensitivity of GeneXpert MTB/RIF to diagnose PTB was 89.00%, and even in patients with negative acid-fast staining, the PTB positive rate was 72.41%.…”

Diagnosis Based on Detection of CXCL10 in Urine as Biomarker for The Determining Diagnosis of Active Lung Tuberculosis

“…20 Meanwhile, research in China shows that high BMI and obesity are associated with the risk of TB infection, possibly because the excess cell adiposity weakens the immune system. 30 The majority of patients showed that vital signs were outside the normal limits, and the results of the study showed that most of the patients had abnormal temperatures, which was in 33.3% of patients. Another study states Indonesian Journal of Tropical and Infectious Disease, Vol.…”

Bifocal Tuberculosis with Adalimumab Revealed by Laryngeal Involvement: Case Report

“…GeneXpert is recommended by the World Health Organization in the pulmonary and extra-pulmonary tuberculosis diagnosis in both immunocompetent and immunocompromised patients [8,9]. It is a rapid molecular test with high performance (sensitivity and specificity) [10].…”

“…It is a rapid molecular test with high performance (sensitivity and specificity) [10]. Multiple gen-eXpert testing on bronchoalveolar lavage fluid can improve the test sensitivity [9].…”