Abstract
Effective treatment of tuberculosis (TB) remains a serious public health problem in many countries, including Brazil, especially when considering drug-resistant disease. Xpert MTB/RIF has been implemented in many countries to reduce the time to TB diagnosis and to rapidly detect rifampicin resistance. The study aimed to describe and evaluate Xpert MTB/RIF performance in diagnosing pulmonary TB and rifampicin resistance in a tertiary healthcare facility in Brazil.
A cross-sectional study was performed, which included all isolates of confirmed pulmonary TB patients from 2015 to 2018. Both Xpert MTB/RIF and GenoType MTBDRplus assays were performed to detect rifampicin and isoniazid resistance. In addition, isolates with detected resistance to rifampicin and/or isoniazid were analysed by phenotypic testing using MGIT-960 SIRE kit and whole-genome sequencing (WGS) using Illumina MiSeq Sequencing System.
2148 respiratory specimens tested with Xpert MTB/RIF were included: n=1556 sputum, n=348 bronchoalveolar lavage and n=244 gastric washing. The overall Xpert MTB/RIF sensitivity in sputum was 94% and the overall specificity was 98%. The negative predictive value in sputum of all the patients was 99% with a positive predictive value of 89%. The concordance between Xpert MTB/RIF and phenotypic susceptibility test was 94.1%, while its concordance with WGS was 78.9%.
Xpert MTB/RIF is a rapid and accurate diagnostic strategy for pulmonary TB, which can contribute to improvement in TB control. However, detection of rifampicin resistance might be associated with false-positive results.
Abstract
Xpert MTB/RIF has the potential to reduce the time to diagnose TB, with high accuracy, including paucibacillary disease. It is also feasible to detect rifampicin resistance, with a high concordance with phenotypic tests and whole-genome sequencing. http://bit.ly/2WW4jmt
Footnotes
Conflict of interest: C.S. Feliciano reports grants from FAPESP during the conduct of the study.
Conflict of interest: L.C.B. Menon has nothing to disclose.
Conflict of interest: L. Anselmo has nothing to disclose.
Conflict of interest: A. Dippenaar has nothing to disclose.
Conflict of interest: R.M. Warren has nothing to disclose.
Conflict of interest: W.A. Silva Jr reports grants from FAPESP during the conduct of the study.
Conflict of interest: V.R. Bollela reports grants from FAPESP during the conduct of the study.
Support statement: Research funding was received from the Fundação de Amparo à Pesquisa do estado de São Paulo (protocol number: 15/13333-3), and Fundação de Apoio ao Ensino, Pesquisa e Assistência do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo. Funding information for this article has been deposited with the Crossref Funder Registry.
- Received February 15, 2019.
- Accepted June 7, 2019.
- Copyright ©ERS 2019
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