Residual malaria among migrant workers in Myanmar: why still persistent and how to eliminate it?

BACKGROUND

Residual malaria is probably an important source for the re-emergence of malaria infection in the elimination era. Assessment to identify the factors influencing residual malaria in high-risk groups is needed to develop evidence-based decisions by stakeholders and policymakers.

METHODS

This study was conducted to explore the factors influencing the residual malaria infection among migrant workers in two sentinel sites (endemic vs. pre-elimination areas) in Myanmar using the mixed-model method.

RESULTS

A total of 102 migrant respondents (65 in Bamauk and 37 in Shwegyin) were included for the quantitative assessment using pretested questionnaires during household visits. Although 87.3% of them had insecticidal bed nets (ITNs/LLINs), only 68.3% of the migrants in Bamauk and 57.9% in Shwegyin used it regularly. The use of any bed net was high (79.9% in Bamauk vs. 91.0% in Shwegyin). The mean LLINs in their families were 1.64 (95%CI: 1.48-1.81) in Bamauk and 2.89 (95%CI: 2.67-3.11) in Shwegyin. Most of them received no health information for malaria prevention within the last year and their knowledge about malaria was low. Their working nature was a challenge for control measures against malaria in migrants.

CONCLUSION

The strategy for distributing LLINs and health promotion activities for mobile/migrant populations should be reviewed, and an appropriate action plan should be developed for the specific migrant group. Moreover, health promotion activities for behavior change communication should be strengthened in the migrant population in Myanmar.

Pyrazinamide resistance and pncA mutations in drug resistant Mycobacterium tuberculosis clinical isolates from Myanmar

Pyrazinamide (PZA) is an important anti-tuberculosis drug, which is active against semi-dormant bacilli and used as a component of first-line drugs and drug-resistant tuberculosis regimens. Mutations in pncA and its promoter region are main cause of PZA resistance. There are limited PZA susceptibility data as there is no routine drug susceptibility testing (DST) for PZA. This study was aimed to determine the proportion of PZA resistance among rifampicin-resistant tuberculosis patients and to identify mutations which are responsible for PZA resistance in pncA and its promoter region. Liquid-based DST was performed to detect PZA susceptibility on 192 culture positive rifampicin-resistant isolates collected from National Tuberculosis Reference Laboratory. Sequencing on pncA including its promoter region was performed and analysis was done on 157 isolates. Phenotypic PZA resistance was detected in 58.9% of isolates. Sixty-five different mutations were distributed in pncA or promoter region of 82 isolates. Sensitivity and specificity of pncA sequencing in detection of PZA resistance showed 89.8% and 95.6% respectively. High proportion of PZA resistance among rifampicin-resistant cases highlighted the need for effective treatment regimen development for PZA-resistant MDR-TB. It is also suggested that routine PZA susceptibility test should be incorporated to treatment monitoring regimen and National Drug Resistance surveys.

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.

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.

Liposomes of probiotic's lyophilized cell free supernatant; a potential cosmeceutical product

The potential uses of lyophilized cell free supernatant (CFS) of human oral derived Lactobacillus paracasei SD1 and Lactobacillus rhamnosus SD11 as cosmeceutical ingredients were investigated in the present study. Lyophilized CFS of both strains showed the antioxidant activity in concentration dependent manner. They also exhibited antimicrobial activity against P. acne, S. aureus and S. epidermidis. In combination, these two strains produced synergistic responses, not only on antioxidant activity but also on antimicrobial activity. A liposomal delivery system was employed to mask the unpleasant colour and odour of CFS. The optimal liposome formulation was characterized by a particle size of 344 nm, PDI of 0.19, zeta value of -48.05 mV and %EE of 69.45. The cytotoxicity results showed that the lyophilized CFS, which was toxic, became non-toxic after encapsulating into liposomes. Altogether, current findings demonstrate the worthiness of development of liposomes of probiotic's lyophilized CFS for cosmeceutical applications.

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.