The impact of sputum quality on Xpert positivity in active case-finding for TB.

BACKGROUND: Studies evaluating sputum quality and Xpert® MTB/RIF positivity in the context of active case finding are scarce. We aimed to determine whether sputum quality is associated with Xpert positivity and whether the association differed according to demographic and clinical characteristics.METHODS: A cross-sectional analysis using data from a mass screening programme in Brazilian prisons was conducted from 2017 to 2021. We administered a standardised questionnaire, obtained a chest X-ray and collected a spot sputum sample for Xpert testing. Sputum quality was classified as 'salivary', 'mucoid/mucopurulent' or 'blood-stained'. We used log binomial regressions to estimate the relationship between sputum quality and Xpert positivity, assessing interactions with participant characteristics.RESULTS: Among 4,368 participants for whom sputum quality was assessed, 957 (21.9%) produced salivary specimens, 3,379 (77.4%) had mucoid/mucopurulent sputum and 32 (0.7%) had blood-stained sputum. Xpert positivity was higher among those with mucoid/mucopurulent sputum than among those with salivary samples (12.0% vs. 3.7%). Mucopurulent sputum independently predicted Xpert positivity among individuals with and without symptoms, current smoking and abnormal chest radiographs on CAD4TB.CONCLUSIONS: In our study, sputum appearance independently predicted Xpert positivity, and could be used together with chest X-ray and symptom screening to inform use of Xpert in individual or pooled testing.

Identification of a predominant genotype of Mycobacterium tuberculosis in Brazilian indigenous population.

After nearly a century of vaccination and six decades of drug therapy, tuberculosis (TB) kills more people annually than any other infectious disease. Substantial challenges to disease eradication remain among vulnerable and underserved populations. The Guarani-Kaiowá people are an indigenous population in Paraguay and the Brazilian state of Mato Grosso do Sul. This community, marginalized in Brazilian society, experiences severe poverty. Like other South American indigenous populations, their TB prevalence is high, but the disease has remained largely unstudied in their communities. Herein, Mycobacterium tuberculosis isolates from local clinics were whole genome sequenced, and a population genetic framework was generated. Phylogenetics show M. tuberculosis isolates in the Guarani-Kaiowá people cluster away from selected reference strains, suggesting divergence. Most cluster in a single group, further characterized as M. tuberculosis sublineage 4.3.3. Closer analysis of SNPs showed numerous variants across the genome, including in drug resistance-associated genes, and with many unique changes fixed in each group. We report that local M. tuberculosis strains have acquired unique polymorphisms in the Guarani-Kaiowá people, and drug resistance characterization is urgently needed to inform public health to ensure proper care and avoid further evolution and spread of drug-resistant TB.

Identification of a predominant genotype of Mycobacterium tuberculosis in Brazilian indigenous population

After nearly a century of vaccination and six decades of drug therapy, tuberculosis (TB) kills more people annually than any other infectious disease. Substantial challenges to disease eradication remain among vulnerable and underserved populations. The Guarani-Kaiowá people are an indigenous population in Paraguay and the Brazilian state of Mato Grosso do Sul. This community, marginalized in Brazilian society, experiences severe poverty. Like other South American indigenous populations, their TB prevalence is high, but the disease has remained largely unstudied in their communities. Herein, Mycobacterium tuberculosis isolates from local clinics were whole genome sequenced, and a population genetic framework was generated. Phylogenetics show M. tuberculosis isolates in the Guarani-Kaiowá people cluster away from selected reference strains, suggesting divergence. Most cluster in a single group, further characterized as M. tuberculosis sublineage 4.3.3. Closer analysis of SNPs showed numerous variants across the genome, including in drug resistance-associated genes, and with many unique changes fixed in each group. We report that local M. tuberculosis strains have acquired unique polymorphisms in the Guarani-Kaiowá people, and drug resistance characterization is urgently needed to inform public health to ensure proper care and avoid further evolution and spread of drug-resistant TB

Contribution of the Ogawa-Kudoh swab culture method to the diagnosis of pulmonary tuberculosis in Brazil.

OBJECTIVE: To analyse the contribution of the Ogawa-Kudoh (O-K) swab culture method to the diagnosis of pulmonary tuberculosis (PTB) in four different regions of Brazil. DESIGN: This study was carried out in two phases. Phase 1 was designed to compare the direct swab culture method (O-K) with the culture concentrated method (N-acetyl-L-cysteine-sodium hydroxide [NALC-NaOH]); for this purpose, 569 sputum samples were cultured by both methods. Phase 2 was carried out to assess the contribution of the O-K method to the diagnosis of PTB in four different regions in Brazil, based on the evaluation of 19,163 sputum samples. RESULTS: In the first phase of the study, O-K culture had a sensitivity of 94.8% and specificity of 99.8% in cases confirmed by NALC-NaOH/Löwenstein-Jensen (LJ) culture. In the second phase of the study, the overall contribution of O-K culture compared to acid-fast bacilli (AFB) examination (AFB-/culture+) to the diagnosis of PTB was 29.8%. CONCLUSION: O-K culture contributes significantly to the diagnosis of smear-negative PTB. Importantly, this method allows the recovery of clinical isolates in areas where use of the standard culture centrifuge is impossible, indicating that the O-K swab culture method should become a standard method for TB diagnosis in these regions.