ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Neetha S Murthy1 , Sanjeev Nair2,3, PK Ramya1, Renu Susan George1,B Ravikrishnan1, M Sunil Kumar4, Sairu Philip5, PS Rakesh6 and Shibu Balakrishnan7
1Intermediate Reference Laboratory for Tuberculosis, Thiruvananthapuram, Kerala- 695035, India.
2State Task Force for Medical Colleges, NTEP, Kerala, India.
3Department of Pulmonary Medicine, Government Medical College, Thiruvananthapuram, Kerala, India.
4State TB Training and Demonstration Center (STDC), National TB Elimination Programme (NTEP), Kerala, India.
5Department of Community Medicine, Government TD Medical College Alappuzha, Kerala, India.
6Medical Consultant World Health Organization, NTEP, Kerala, India.
7National TWG Member, RTL South, WHO, India.
J Pure Appl Microbiol. 2021;15(4):1882-1891 | Article Number: 6969 | © The Author(s). 2021
Received: 05/04/2021 | Accepted: 14/09/2021 | Published: 04/10/2021

Resistance to antimycobacterial agents consistently remains a major obstacle to end TB in India. Geographical prevalence data regarding drug-resistant evolutionary genetics of  M. tuberculosis (MTB) remains sparse in India. Our objective was to determine the genotypic drug resistance mutation pattern for Rifampicin and Isoniazid of MTB isolates to gain an understanding of the prevailing molecular epidemiology of drug-resistant tuberculosis. In this study 2528 M. tuberculosis DNA isolates from presumptive DRTB suspects received at the nodal TB reference laboratory in Kerala were tested for Rifampicin and Isoniazid resistance by sequence-based diagnostic Line Probe assay (LPA). Geographical prevalence and associations of rpoB, katG, inhA resistance codons was analyzed from January 2019 to March 2020. Among the 2528 DNA samples subjected for Rifampicin and Isoniazid resistance determination by LPA, 146 (5.8%) isolates were resistant to both drugs. Isoniazid mono-resistance was found in 164 (6.5%) and Rifampicin mono-resistance in 38 (1.5%) isolates. The most frequent rpoB mutation was S531L (60.32%) followed by S531W/L533P mutations seen in 8.15% of the isolates. S315T1 KatG mutation was seen in 97.33% of Isoniazid resistant isolates. 84.68% isolates with rpoB S531L mutation were found to be multidrug-resistant. 82.9% of isolates with rpoB S531L mutation showed katG S315T1 mutation. Mono isoniazid-resistant isolates were significantly higher compared to mono rifampicin-resistant isolates among the DNA isolates studied in our region. The molecular epidemiological pattern most frequently associated with multidrug resistance was rpoB S531L which was significantly associated with the co-presence of S315T1 mutation.


Mycobacterium tuberculosis, Multi-drug resistance, rpoB, katG, inhA mutations

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© The Author(s) 2021. 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.