Title |
Molecular characterisation of rifampicin-resistant Mycobacterium tuberculosis strains from Malawi
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Published in |
African Journal of Laboratory Medicine, March 2017
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DOI | 10.4102/ajlm.v6i2.463 |
Pubmed ID | |
Authors |
Tarsizio Chikaonda, Irene Ketseoglou, Nelson Nguluwe, Robert Krysiak, Isaac Thengolose, Felix Nyakwawa, Nora E. Rosenberg, Christopher Stanley, James Mpunga, Irving F. Hoffman, Maria A. Papathanasopoulos, Mina Hosseinipour, Lesley Scott, Wendy Stevens |
Abstract |
Availability and access to the detection of resistance to anti-tuberculosis drugs remains a significant challenge in Malawi due to limited diagnostic services. The Xpert(®) MTB/RIF can detect Mycobacterium tuberculosis and resistance to rifampicin in a single, rapid assay. Rifampicin-resistant M. tuberculosis has not been well studied in Malawi. We aimed to determine mutations in the rifampicin resistance determining region (RRDR) of the rpoB gene of M. tuberculosis strains which were defined as resistant to rifampicin by the Xpert MTB/RIF assay. Rifampicin-resistant isolates from 43 adult patients (≥ 18 years) from various districts of Malawi were characterised for mutations in the RRDR (codons 507-533) of the rpoB gene by DNA sequencing. Mutations were found in 37/43 (86%) of the resistant isolates in codons 511, 512, 513, 516, 522, 526 and 531. The most common mutations were in codons 526 (38%), 531 (29.7%) and 516 (16.2%). Mutations were not found in 6/43 (14%) of the resistant isolates. No novel rpoB mutations other than those previously described were found among the rifampicin-resistant M. tuberculosis complex strains. This study is the first to characterise rifampicin resistance in Malawi. The chain-termination DNA sequencing employed in this study is a standard method for the determination of nucleotide sequences and can be used to confirm rifampicin resistance obtained using other assays, including the Xpert MTB/RIF. Further molecular cluster analysis, such as spoligotyping and DNA finger printing, is still required to determine transmission dynamics and the epidemiological link of the mutated strains. |
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Members of the public | 1 | 100% |
Mendeley readers
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Unknown | 45 | 100% |
Demographic breakdown
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Student > Ph. D. Student | 8 | 18% |
Researcher | 6 | 13% |
Student > Master | 4 | 9% |
Student > Bachelor | 3 | 7% |
Other | 2 | 4% |
Other | 4 | 9% |
Unknown | 18 | 40% |
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Immunology and Microbiology | 6 | 13% |
Nursing and Health Professions | 4 | 9% |
Biochemistry, Genetics and Molecular Biology | 3 | 7% |
Agricultural and Biological Sciences | 2 | 4% |
Other | 4 | 9% |
Unknown | 20 | 44% |