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Drug Resistance Conferring Mutation and Genetic Diversity of Mycobacterium tuberculosis Isolates in Tuberculosis Lymphadenitis Patients; Ethiopia

Authors Ayalew S, Wegayehu T, Taye H, Wassie L, Girma S, Berg S, Mihret A

Received 22 December 2020

Accepted for publication 31 January 2021

Published 15 February 2021 Volume 2021:14 Pages 575—584


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Professor Suresh Antony

Sosina Ayalew,1,2 Teklu Wegayehu,2 Hawult Taye,1 Liya Wassie,1 Selfu Girma,1 Stefan Berg,3 Adane Mihret1

1Armauer Hansen Research Institute, Addis Ababa, Ethiopia; 2Department of Biology, College of Natural Sciences, Arba Minch University (AMU), Arba Minch, Ethiopia; 3Bacteriology Department, Animal and Plant Health Agency, Weybridge, UK

Correspondence: Sosina Ayalew Tel +251 912166324

Background: Tuberculosis lymphadenitis (TBLN) is a growing public health concern in Ethiopia. However, there is limited information available on gene mutations conferring drug resistance and genetic diversity of M. tuberculosis isolates from TBLN patients.
Methods: Drug resistance and genetic diversity analysis were done on 91 M. tuberculosis isolates from culture positive TBLN patients collected between 2016 and 2017. Detection of mutations conferring resistance was carried out using GenoType MTBDRplus VER 2.0. Thereafter, isolates were typed using spoligotyping.
Results: Out of the 91 strains, mutations conferring resistance to rifampicin (RIF) and isoniazid (INH) were observed in two (2.2%) and six (6.6%) isolates, respectively. The two RIF resistant isolates displayed a mutation at codon 531 in the rpoB gene with amino acid change of S531L. Among the six INH resistant strains, four isolates had shown mutation at the KatG gene at codon 315 with amino acid change of S315T, one isolate had a mutation at the inhA gene at codon 15 with amino acid change of C15T and one isolate had a mutation at the inhA gene with unknown amino acid change. All drug resistant isolates were from treatment naive TBLN patients. The dominantly identified Spoligo International Types (SITs) were SIT25, SIT149, and SIT53, respectively; these accounted for 43% of the total number of strains. The isolates were grouped into four main lineages; Lineage 1 (2, 2.2%), Lineage 3 (38, 41.7%), Lineage 4 (49, 53.8%) and Lineage 7 (2, 2.2%). Four out of six (66.7%) isolates with drug resistance conferring mutations belonged to clustered strains (strains with shared SIT).
Conclusion: The detection of drug resistant conferring mutation in treatment naïve TBLN patients together with detection of drug resistant isolates among clustered strains might suggest resistant strains’ transmission in the community. This needs to be carefully considered to prevent the spread of drug resistant clones in the country.

Keywords: drug resistant, genetic diversity, mutation, tuberculosis lymphadenitis

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