The occurrence and frequency of genomic mutations that mediate Isoniazid and Rifampicin resistance in Mycobacterium tuberculosis isolates from untreated pulmonary Tuberculosis cases in urban Blantyre, Malawi
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Background The emergence and spread of drug-resistant Tuberculosis (TB) is a major public health threat. TB resistance originates in the course of treatment due to genomic mutations in Mycobacterium tuberculosis (MTB). An increase in new cases with drug-resistant TB could be an indicator of high levels of circulating resistant strains. This study was conducted to determine the occurrence and frequency of genomic mutations that mediate Isoniazid (INH) and Rifampicin (RIF) resistance among isolates from untreated TB cases in urban Blantyre, Malawi. Methods A cross-sectional retrospective study was conducted on a panel of 141(n=141) MTB clinical isolates recovered between June 2010 and January 2012 from ≥2+ Ziehl-Neelsen smear positive new pulmonary-TB patients with no history of treatment. Frozen isolates were revived using the BACTEC MGIT detection system. DNA was extracted using GenoLyse DNA extraction kit and detection of genomic mutations was carried out using the GenoType MTBDRplus Ver 2.0 assay. Results Out of the 141 isolates studied, 3 (2.1%) were found carrying mutations in the katG gene that confer resistance to Isoniazid (INH). No mutations were detected in the inhA promoter region gene that confer weak INH resistance or in the rpoB gene that confer Rifampicin resistance. All katG mutant genes had a S315T1 single point mutation, a genomic alteration that mediates high INH resistance. Conclusion The katG mutant gene conferring resistance to INH was the only genomic mutation observed among the isolates studied and the frequency of occurrence was low. Our findings suggest low levels of circulating drug-resistant MTB strains in urban Blantyre, Malawi.
Kumwenda , G P , Chipungu , G , Sloan , D J , Kaimila , Y , Chiumya , K & Pangani , H 2018 , ' The occurrence and frequency of genomic mutations that mediate Isoniazid and Rifampicin resistance in Mycobacterium tuberculosis isolates from untreated pulmonary Tuberculosis cases in urban Blantyre, Malawi ' Malawi Medical Journal , vol 30 , no. 1 , pp. 1-5 . DOI: 10.4314/mmj.v30i1.1
Malawi Medical Journal
© 2018 The College of Medicine and the Medical Association of Malawi. This work is licensed under the Creative Commons Attribution 4.0 International License. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
DescriptionThis study was funded by the Helse Nord Tuberculosis Initiative (HNTI), a College of Medicine grant supported by the Helse Nord RHF and the University of Tromso.
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