Genetic diversity of Mycobacterium tuberculosis using 24-locus MIRU-VNTR typing and Spoligotyping in Upper Myanmar.

INTRODUCTION: MIRU-VNTR typing and Spoligotyping are the useful molecular tools for TB epidemiology study. Information regarding genetic diversity and tuberculosis (TB) transmission in Upper Myanmar only is scares. METHODOLOGY: We determined the genetic diversity of Mycobacterium tuberculosis (Mtb) and TB transmission from Upper Myanmar TB Reference Laboratory, Mandalay Region, including Mandalay (72), Shan (22), Magway (15), Sagaing (13), Nay Pyi Taw (8), Kachin (7), Chin (2) and Kayah (1). One hundred and forty Mtb isolates were genotyped using 24-locus MIRU-VNTR typing and spoligotyping. Lineage classification and TB transmission analysis were performed. RESULTS: 24-locus MIRU-VNTR typing identified 135 unique profiles and two clusters compared to 35 spoligotyping profiles which contained 12 clusters and 23 unique isolates, Beijing (n=100, 71.4%) was found to be prominent lineage by combine two methods. The expected proportion attributable to recent transmission based on clustering rate was 2.1%. One cluster case was more likely to be in MDR patient. CONCLUSIONS: Our findings showed Beijing genotypes were dominant in Upper Myanmar. The usage and analysis of 24-locus MIRU-VNTR typing might prove useful for our broader understanding of TB outbreaks and epidemiology than spoligotyping. The genotypic pattern of this combined method suggests that the lower transmission rate may be due to a higher possibility of reactivation cases in Upper Myanmar.

Genotypes and genetic characters of Mycobacterium tuberculosis from Myanmar using three typing methods.

Knowledge on basic characteristics of Mycobacterium tuberculosis (MTB) is helpful to understand the disease epidemiology and support the prediction of clinical outcome of the disease. The aim of this study was to detect the genotypes and genotypic characters of clinical Mycobacterium tuberculosis (MTB) isolates from new and retreatment rifampicin-resistant patients using three different genotyping methods. Mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) typing was used to determine the diversity of 222 clinical isolates. Spoligotyping and IS6110-restriction fragment length polymorphism (RFLP) typing were also used to investigate the genetic characters of 105 MTB strains. Among the 15 genotypes detected by MIRU-VNTR, Beijing strains were the most prevalent of all strains (54.8%); new cases (40.5%) and retreatment cases (69.4%), followed by EAI strain. Spoligotyping categorized the strains into 11 lineages and 13 orphans whereas 96 different IS6110 patterns were identified using RFLP method. The mode number of IS6110 was 18 and 20. Higher band numbers were found in Beijing genotype (p < 0.001). Clustering rates by spoligotyping, MIRU-VNTR and IS6110-RFLP typing were 0.714, 0.004 and 0.085, respectively. Discriminatory powers of spoligotyping, MIRU-VNTR typing and IS6110-RFLP typing were 0.637, 1.000 and 0.997, respectively. Dominant Beijing genotype in both new and retreatment cases denoting that prevailing tuberculosis in Myanmar changed from EAI to Beijing lineage.

Phenotypic and genotypic analysis of anti-tuberculosis drug resistance in Mycobacterium tuberculosis isolates in Myanmar.

BACKGROUND: Tuberculosis (TB) is one of the most serious health problems in Myanmar. Because TB drug resistance is associated with genetic mutation(s) relevant to responses to each drug, genotypic methods for detecting these mutations have been proposed to overcome the limitations of classic phenotypic drug susceptibility testing (DST). We explored the current estimates of drug-resistant TB and evaluated the usefulness of genotypic DST in Myanmar. METHODS: We determined the drug susceptibility of Mycobacterium tuberculosis isolated from sputum smear-positive patients with newly diagnosed pulmonary TB at two main TB centers in Myanmar during 2013 by using conventional phenotypic DST and the GenoType MTBDRplus assay (Hain Lifescience, Germany). Discrepant results were confirmed by sequencing the genes relevant to each type of resistance (rpoB for rifampicin; katG and inhA for isoniazid). RESULTS: Of 191 isolates, phenotypic DST showed that 27.7% (n=53) were resistant to at least one first-line drug and 20.9% (n=40) were resistant to two or more, including 18.3% (n=35) multidrug-resistant TB (MDR-TB) strains. Monoresistant strains accounted for 6.8% (n=13) of the samples. Genotypic assay of 189 isolates showed 17.5% (n=33) MDR-TB and 5.3% (n=10) isoniazid-monoresistant strains. Genotypic susceptibility results were 99.5% (n=188) concordant and agreed almost perfectly with phenotypic DST (kappa=0.99; 95% confidence interval 0.96-1.01). CONCLUSIONS: The results highlight the burden of TB drug resistance and prove the usefulness of the genotypic DST in Myanmar.