Ann Lab Med 2018; 38(2): 119-124  https://doi.org/10.3343/alm.2018.38.2.119
Comparative Evaluation of the Loop-Mediated Isothermal Amplification Assay for Detecting Pulmonary Tuberculosis
Chang-Ki Kim, M.D.1,*, Eun A Cho, M.S.2, Dong Mi Shin, M.S.2, Sung Won Choi, B.S.2, and So Youn Shin, M.D.2
Department of Laboratory Medicine1, Hanyang University Guri Hospital, Guri; Korean Institute of Tuberculosis2, Cheongju, Korea
Corresponding author: Chang-Ki Kim
Department of Laboratory Medicine, Hanyang University Guri hospital, 153 Gyeongchun-ro, Guri 11923, Korea
Tel: +82-31-560-2486
Fax: +82-31-560-2489
E-mail: psoas95@gmail.com
*Present affiliation: Department of Laboratory Medicine, Seoul Clinical Laboratories, Yongin, Korea.
Received: February 2, 2017; Revised: July 7, 2017; Accepted: October 10, 2017; Published online: March 1, 2018.
© Korean Society for Laboratory Medicine. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: Early detection of tuberculosis (TB) is challenging in resource-poor settings because of limited accessibility to molecular diagnostics. The aim of this study was to evaluate the performance of the loop-mediated isothermal amplification kit (TB-LAMP) for TB diagnosis compared with conventional and molecular tests.
Methods: A total of 290 consecutive sputum samples were collected from May till September, 2015. All samples were processed using the N-Acetyl-L-cysteine (NALC) NaOH method and tested by smear microscopy, solid and liquid culture, real-time PCR, and TB-LAMP.
Results: The sensitivity of TB-LAMP for smear-positive and smear-negative samples with culture positivity was 92.0% and 58.8%, respectively. TB-LAMP was positive in 14.9% of TB culture-negative samples; however, all those samples were also positive by real-time PCR. In addition, none of the samples positive for nontuberculous mycobacteria by culture were positive by TB-LAMP. The overall agreement between TB-LAMP and real-time PCR was good; however, the concordance rate was significantly lower for real-time PCR positive samples with Ct values of 30–35.
Conclusions: TB-LAMP could replace smear microscopy and increase TB diagnostic capacity when Xpert MTB/RIF is not feasible because of poor infrastructure.
Keywords: Tuberculosis, TB-LAMP, Real-time PCR, Sensitivity, Specificity



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