ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Vishnu Prasad Shenoy , Ajay Kumar and Kiran Chawla
Department of Microbiology, Kasturba Medical College Manipal, Manipal Academy of Higher Education, Karnataka, India.
J Pure Appl Microbiol, 2019, 13 (3): 1461-1465 | Article Number: 5775
Received: 28/07/2019 | Accepted: 02/09/2019 | Published: 30/09/2019

GeneXpert MTB/RIF assay (GeneXpert) is relatively new technology in India and it is important to generate data on its efficacy for diagnosis of Tuberculosis. Thus; present study was undertaken to compare the diagnostic performance of GeneXpert for diagnosis of pulmonary tuberculosis (PTB) in comparison with Auramine O staining based Light Emitting Diode- Fluorescence Microscopy (LED-FM) considering culture as gold standard. A total of 662 (451 BAL, 211 Sputum) respiratory samples obtained from patients suspected of PTB were tested for smear microscopy and GeneXpert assay and were compared with culture results. Rifampicin resistance was compared with Genotype MTBDR plus assay. Sensitivity, specificity, positive predictive value (PPV) and negative predictive values (NPV) of the assays were calculated using SPSS version 22. On comparing with culture the sensitivity, specificity, PPV and NPV of GeneXpert MTB/RIF was found to be 97.25%, 98.54%, 96.20% and 98.95% respectively whereas sensitivity,  specificity, PPV and NPV of smear microscopy was found to be 73.08%, 100%, 100% and 90.74% respectively. Rifampicin resistance was detected in 11 (1.66%) samples by GeneXpert. Five (0.75%) samples among them were found to be MDR whereas one sample showed false positive result for rifampicin resistant when compared by Genotype MTBDR plus assay. GeneXpert MTB/RIF assay offers much higher sensitivity as compared to Auramine O staining based LED-FM and seems to be a promising tool for TB diagnosis. Further longitudinal studies are required to evaluate the potential of this assay at primary health care settings and diagnosis of Extrapulmonary TB.


Culture, Diagnosis, GeneXpert, Microscopy, Mycobacterium tuberculosis.

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© The Author(s) 2019. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.