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Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray
Published on: April 25, 2014
Genotype diversity of Mycobacterium isolates from children in Jimma, Ethiopia
Bereket Workalemahu1, Stefan Berg, Wondewosen Tsegaye
1Armauer Hansen Research Institute (AHRI/ALERT), Addis Ababa, Ethiopia. bekicho@gmail.com.
Insights
This study investigated paediatric tuberculosis in Ethiopia, finding no multidrug-resistant strains and suggesting active adult-to-child transmission of Mycobacterium tuberculosis. Genetic analysis revealed similarities between paediatric and adult TB strains.
Area of Science:
- Microbiology
- Genetics
- Public Health
Background:
- Paediatric tuberculosis (TB) is under-researched in Ethiopia.
- Limited data exists on TB magnitude and Mycobacterium tuberculosis genotype distribution in children.
Purpose of the Study:
- To investigate the genetic diversity of Mycobacterium tuberculosis strains causing paediatric TB in Ethiopia.
- To assess drug resistance patterns in paediatric TB isolates.
Main Methods:
- Collected gastric lavage and sputum samples from TB-suspect children.
- Used molecular techniques including PCR, gene sequencing, and spoligotyping for M. tuberculosis identification and lineage classification.
- Performed molecular drug susceptibility testing using line probe assay.
Main Results:
- Identified M. tuberculosis in 31.7% of samples; 60% of isolates were M. tuberculosis, 40% were non-tuberculous mycobacteria.
- Classified M. tuberculosis strains into Euro-American (66.7%), EAI (13.3%), EA (6.7%), and IO (6.7%) lineages.
- Found all isolates susceptible to isoniazid and rifampicin, with one strain showing low-level INH resistance due to an inhA locus mutation.
Conclusions:
- Paediatric M. tuberculosis strains in Ethiopia show genetic similarities to adult strains, indicating ongoing adult-to-child transmission.
- No multidrug-resistant TB strains were detected among the studied paediatric isolates.
Background:
Paediatric tuberculosis (TB) is poorly addressed in Ethiopia and information about its magnitude and the genotype distribution of the causative Mycobacterium tuberculosis strains responsible for its spread are scanty.
Methods:
Gastric lavage or sputum samples were collected from consecutively enrolled TB suspect children visiting Jimma University Hospital in 2011 and cultured on Middlebrook 7H11 and Löwenstein-Jensen media. Acid fast bacterial (AFB) isolates were subjected to molecular typing targeting regions of difference (RDs), 16S rDNA gene and the direct repeat (DR) region using multiplex polymerase chain reaction (mPCR), gene sequencing and spoligotyping, respectively. Molecular drug susceptibility testing of M. tuberculosis isolates was performed by Genotype®MTBDRplus line probe assay (LPA) (Hain Life Sciences, Germany).
Results:
Gastric lavage (n = 43) or sputum (n = 58) samples were collected from 101 children and 31.7% (32/101) of the samples were positive for AFB by microscopy, culture and/or PCR. Out of 25 AFB isolates, 60% (15/25) were identified as M. tuberculosis by PCR, and 40% isolates (10/25) were confirmed to be non-tuberculous mycobacteria (NTM) by genus typing and 16S rDNA gene sequencing. Lineage classification assigned the M. tuberculosis strains into Euro-American (EUA, 66.7%; 10/15), East-African-Indian (EAI; 2/15), East-Asian (EA; 1/15) and Indio-Oceanic (IO; 1/15) lineages. Seven M. tuberculosis strains were new to the SpolDB4 database. All of the M. tuberculosis isolates were susceptible to isoniazid (INH) and rifampicin (RIF), except for one strain (of spoligotype SIT-149 or T3_ETH family) which had a mutation at the inhA locus which often confers resistance to INH (low level) and ethionamide.
Conclusions:
Analysis of the genetic population structure of paediatric M. tuberculosis strains suggested similarity with that of adults, indicating an on-going and active transmission of M. tuberculosis from adults to children in Ethiopia. There were no multidrug-resistant TB (MDR-TB) strains among the isolates.
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