Evaluation of the MolecuTech® REBA MTB-XMDR kit for detection of pre-extensively drug-resistant TB.

BACKGROUND: Rapid diagnosis of drug-resistant TB is critical for early initiation of effective therapy. YD Diagnostics in South Korea recently developed the MolecuTech® REBA MTB-XMDR test to rapidly detect multidrug-resistant TB (MDR-TB), pre-extensively drug-resistant TB (pre-XDR-TB) and resistance to second-line injectable drugs (SLIDs) simultaneously using a fully automated test platform. This study aimed to evaluate the MolecuTech® test for the detection of MDR- and pre-XDR-TB, as well as SLID resistance.METHODS: A total of 151 clinical Mycobacterium tuberculosis isolates from South Korea were tested using the MolecuTech test, and the results were analysed by comparing these with phenotypic drug susceptibility testing (pDST) and sequencing.RESULTS: Compared to pDST, the MolecuTech test showed a sensitivity and specificity of respectively 97.7% and 100.0% for rifampicin (RIF), 82.4% and 100.0% for isoniazid (INH), 97.5% and 97.2% for fluoroquinolones (FQs), and 94.0% and 98.8% for SLIDs. Concordances with the sequencing results of each resistance determinant were 99.3% for RIF, 96.7% for INH, 98.7% for FQs and 99.3% for SLIDs.CONCLUSION: The MolecuTech test is an efficient and reliable rapid molecular diagnostic tool for the simultaneous screening of MDR- and pre-XDR-TB.

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.

Improved method of direct microscopy for detection of acid-fast bacilli in sputum.

Microscopy of direct smears for acid-fast bacilli (AFB) is the most commonly used method for diagnosis of tuberculosis. However, direct microscopy of sputum, though rapid, has low sensitivity and there is a need for improved methods. Sputum samples were collected from patients attending the Union Tuberculosis Institute, Yangon. The microscopy of smears made directly from sputum were compared with the microscopy after liquefaction of sputum with household bleach (NaOCl) and concentration of bacteria by centrifugation. Out of 948 samples, 248 samples (26.2%) were positive for acid-fast bacilli by direct microscopy and 293 samples (30.9%) were positive for acid-fast bacilli by the household bleach method. There was a significant increase in the number of acid-fast bacilli positive samples by the house-hold bleach method (p<0.05). The method is simple and cheap. As a disinfectant, household bleach has the advantage of lowering the risk of laboratory infection.

Relationship of breast-feeding and hand-washing with dehydration in infants with diarrhoea due to Escherichia coli.

This prospective cohort study was carried out in the neonatal unit of the Yangon Children Hospital, Myanmar, to gather more information on the types of feedings and hand-washing practices of mothers as the determinant of severe dehydration in infants with acute diarrhoea due to Escherichia coli. The study subjects included 100 infants with diarrhoea, aged less than 4 months, admitted to the hospital from June 1997 to May 1998. Data on isolation of E. coli from rectal swab samples, types of feedings, hand-washing practices, and dehydration status were collected. Of the 100 cases, E. coli was isolated from rectal swab samples of 48 infants. Of these 48 cases, 28 had some dehydration and 20 had severe dehydration. Exclusive breast-feeding was observed only in the age group < 1 and > 1-2 month(s). The association of the severity of dehydration with other types of feedings compared to exclusive breast-feeding was not statistically significant. In this study, most mothers washed their hands with water only after cleansing their children's defaecation, and before and after feeding their children. The severity of dehydration was statistically significant in hand-washing practices when compared to washing with water only and washing with soap and water. This study has shown the association between types of feedings and hand-washing practices with dehydration in infants with acute diarrhoea due to E. coli. The results of the study suggest that there is a need for appropriate intervention programmes to promote exclusive breast-feeding and hand-washing practices with soap and water after cleansing children's defaecation, and before and after feeding children.