Evaluation of Xpert® MTB/RIF assay as a diagnostic test for pulmonary tuberculosis in children in Myanmar.

BACKGROUND: The Xpert® MTB/RIF assay has been recommended for the diagnosis of pulmonary tuberculosis (PTB). However, there are limited data from the South-East Asian region. SETTING: This study was carried out at a tertiary-level children's hospital in Mandalay, Myanmar. OBJECTIVE: To evaluate the performance of Xpert as a diagnostic test for PTB in children. METHODS: A cross-sectional descriptive study of children with suspected PTB. Gastric lavage aspirate samples were tested using Xpert, solid culture and smear microscopy. The performance of Xpert, solid culture and smear microscopy were evaluated using the revised National Institute of Health classification for intrathoracic TB in children as the reference standard. RESULTS: TB was bacteriologically confirmed in 38 (16.5%) of 231 children with suspected PTB. Of the 38 children with confirmed TB, 36 cases were identified using Xpert, 16 using solid culture and 12 using smear microscopy. With confirmed TB as the reference standard, the sensitivity of Xpert, solid culture and smear microscopy was respectively 94.7% (95%CI 80.9-99.1), 42.1% (95%CI 26.7-59.1) and 31.6% (95%CI 18.0-48.8). CONCLUSION: Xpert has improved the bacteriological confirmation of PTB among hospitalised children in Myanmar.

Extensively drug-resistant tuberculosis in Myanmar: burden and mutations causing second-line drug resistance.

SETTING: Two tuberculosis (TB) reference laboratories in Myanmar. OBJECTIVES: To determine the proportion of extensively drug-resistant TB (XDR-TB) cases among multidrug-resistant TB (MDR-TB) cases and the mutations that cause resistance to second-line drugs in Myanmar. DESIGN: This was a cross-sectional, retrospective study. Multidrug-resistant Mycobacterium tuberculosis isolates were collected during 2015-2016. Phenotypic drug susceptibility testing (DST) was performed and drug-resistant mutations identified by sequencing. Genotypes were determined to explain relationships between drug resistance patterns and genotypes. RESULTS: Of 89 MDR-TB isolates, 12 were XDR-TB and 24 were pre-XDR-TB, with 21 resistant to fluoroquinolones (FQs) and 3 to second-line injectable agents (SLIDs). High rates of cross-resistance among second-line drugs were observed. Correlations between phenotypic and molecular DST against FQs and SLIDs were 91% in both cases. The most frequent mutation in FQ-resistant isolates was D94G (8/21) in gyrA and A1401G (11/15) in rrs in those resistant to SLIDs. The dominant genotype was the Beijing type (76/89). CONCLUSION: There were high proportions of XDR-TB and pre-XDR-TB among MDR-TB cases; cross-resistance among second-line drugs was high, with various types of genetic mutations. These data suggest that resistance to second-line anti-tuberculosis drugs should be monitored intensively, and molecular DST should be employed.