Ann Lab Med.  2015 Sep;35(5):494-499. 10.3343/alm.2015.35.5.494.

Phenotypic and Genotypic Analysis of Anti-Tuberculosis Drug Resistance in Mycobacterium tuberculosis Isolates in Myanmar

• Aung WW
• Ei PW
• Nyunt WW
• Swe TL
• Lwin T
• Htwe MM
• Kim KJ
• Lee JS
• Kim CK
• Cho SN
• Song SD
• Chang CL

• KMID: 2369764
• DOI: http://doi.org/10.3343/alm.2015.35.5.494

Abstract

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.

Keyword

Mycobacterium tuberculosis; Drug; Resistance; Genotype; Myanmar

MeSH Terms

Drug Resistance*
Genotype
Humans
Myanmar*
Mycobacterium tuberculosis*
Rifampin
Sputum
Tuberculosis
Rifampin

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