Prevalence and associated risk factors of drug-resistant tuberculosis in Thailand: results from the fifth national anti-tuberculosis drug resistance survey.

OBJECTIVE: To assess the prevalence and risk factors of drug-resistant tuberculosis (TB), the fifth national anti-TB drug resistance survey was conducted in Thailand. METHODS: A cross-sectional study was conducted by stratified cluster sampling with probability proportional to size of TB cases from public health facilities in 100 clusters throughout Thailand from August 2017 to August 2018. Susceptibility testing of TB isolates to first- and second-line anti-TB drugs was performed on Löwenstein-Jensen medium using the indirect proportion method. Multiple imputation was done for handling missing data using Stata 16. The proportion of TB cases with drug resistance was determined. The odds ratio was used to evaluate risk factors associated with drug-resistant TB. RESULTS: Among 1501 new TB and 69 previously treated TB cases, 14.0% [95% confidence interval (CI): 12.1-16.1] and 33.4% (95% CI: 23.6-44.8), respectively, had resistance to any anti-TB drug. Multidrug-resistant TB accounted for 0.8% (95% CI: 0.5-1.4) of new TB cases and 13.0% (95% CI: 6.5-24.4) of previously treated TB cases. Drug-resistant TB was associated with prior TB treatment [odds ratio (OR), 2.9; 95% CI: 1.6-5.0], age at 45-54 years (OR, 1.6; 95% CI: 1.0-2.4), male (OR, 1.5; 95% CI: 1.0-2.1) and human immunodeficiency virus (HIV) infection (OR, 1.6; 95% CI: 1.0-2.4). CONCLUSIONS: The burden of drug-resistant TB remains high in Thailand. Intensified prevention and control measures should be implemented to reduce the risks of drug-resistant TB in high-risk groups previously treated, especially individuals of late middle age, males and those with coinfection of TB and HIV.

Use of network analysis multidrug-resistant tuberculosis contact investigation in Kanchanaburi, Thailand.

OBJECTIVE: To characterise MDR-TB outbreak and incorporate social network analysis with contact investigation to detect case-contact linkages and clusters. METHODS: MDR-TB cases registered in the district hospital between October 2012 and September 2015 were interviewed and their contacts were investigated. A relationship-based weighted network was constructed. RESULTS: Among 43 interviewed MDR-TB cases, 20 (47%) were male, five (12%) were asymptomatic (and discovered incidentally) and 22 (51%) had underlying diseases. From the documented 115 contacts, 61 (53%) were household contacts and 49 (43%) were close (non-household) contacts; 70 (61%) were screened for TB using various tests. In this network, we prioritised 37 contacts connected with more than one MDR-TB patient. The largest cluster was identified in the pharmacy unit of the hospital. CONCLUSION: This investigation yielded a significant number of MDR-TB contacts, and social network analysis facilitated the prioritisation for screening. Social network analysis is useful and feasible in this program setting and complements MDR-TB contact investigation.

OBJECTIF: Caractériser une épidémie de TB-MDR et incorporer une analyse du réseau social avec une investigation sur les contacts pour détecter les liens et les regroupements cas-contacts. MÉTHODES: Les cas de TB-MR enregistrés à l'hôpital de district entre octobre 2012 et septembre 2015 ont été interrogés et leurs contacts ont été investigués. Un réseau pondéré sur base de la relation a été construit. RÉSULTATS: Sur 43 cas de TB-MDR interviewés, 20 (47%) étaient des hommes, cinq (12%) étaient asymptomatiques (et ont été découverts fortuitement) et 22 (51%) avaient des maladies sous-jacentes. Parmi les 115 contacts recensés, 61 (53%) étaient des contacts dans le ménage et 49 (43%) étaient des contacts proches (hors ménage); 70 (61%) ont été dépistés pour la TB à l'aide de divers tests. Dans ce réseau, nous avons priorisé 37 contacts reliés à plus d'un patient atteint de TB-MR. Le regroupement le plus important a été identifié dans l'unité de pharmacie de l'hôpital. CONCLUSION: Cette investigation a abouti à un nombre important de contacts avec la TB-MDR et l'analyse du réseau social a facilité l'établissement des priorités pour le dépistage. L'analyse du réseau social est utile et réalisable dans le cadre de ce programme et complète l'investigation sur les contacts de TB-MDR.

Diagnostic value of blood gene expression signatures in active tuberculosis in Thais: a pilot study.

Tuberculosis (TB) is a major global health problem. Routine laboratory tests or newly developed molecular detection are limited to the quality of sputum sample. Here we selected genes specific to TB by a minimum redundancy-maximum relevancy package using publicly available microarray data and determine level of selected genes in blood collected from a Thai TB cohort of 40 active TB patients, 38 healthy controls and 18 previous TB patients using quantitative real-time PCR. FCGR1A, FCGR1B variant 1, FCGR1B variant 2, APOL1, GBP5, PSTPIP2, STAT1, KCNJ15, MAFB and KAZN had significantly higher expression level in active TB individuals as compared with healthy controls and previous TB cases (P<0.01). A mathematical method was applied to calculate TB predictive score, which contains the level of expression of seven genes and this score can identify active TB cases with 82.5% sensitivity and 100% specificity as compared with conventional culture confirmation. In addition, TB predictive scores in active TB patients were reduced to normal after completion of standard short-course therapy, which was mostly in concordant with the disease outcome. These finding suggested that blood gene expression measurement and TB Sick Score could have potential value in terms of diagnosis of TB and anti-TB treatment monitoring.

Association analysis of susceptibility candidate region on chromosome 5q31 for tuberculosis.

Chromosome 5q31 spans the T helper (Th) 2-related cytokine gene cluster, which is potentially important in Th1/Th2 immune responses. The chromosome 5q23.2-31.3 has been recently identified as a region with suggestive evidence of linkage to tuberculosis in the Asian population. With the aim of fine-mapping a putative tuberculosis susceptibility locus, we investigated a family-based association test between the dense single nucleotide polymorphism (SNP) markers within chromosome 5q31 and tuberculosis in 205 Thai trio families. Of these, 75 SNPs located within candidate genes covering SLC22A4, SLC22A5, IRF1, IL5, RAD50, IL13, IL4, KIF3A and SEPT8 were genotyped using the DigiTag2 assay. Association analysis revealed the most significant association with tuberculosis in haplotypes comprising SNPs rs274559, rs274554 and rs274553 of SLC22A5 gene (P(Global)=2.02 x 10(-6)), which remained significant after multiple testing correction. In addition, two haplotypes within the SLC22A4 and KIF3A region were associated with tuberculosis. Haplotypes of SLC22A5 were significantly associated with the expression levels of RAD50 and IL13. The results show that the variants carried by the haplotypes of SLC22A4, SLC22A5 and KIF3A region potentially contribute to tuberculosis susceptibility among the Thai population.

Genome-wide SNP-based linkage analysis of tuberculosis in Thais.

Tuberculosis, a potentially fatal infectious disease, affects millions of individuals annually worldwide. Human protective immunity that contains tuberculosis after infection has not been clearly defined. To gain insight into host genetic factors, nonparametric linkage analysis was performed using high-throughput microarray-based single nucleotide polymorphism (SNP) genotyping platform, a GeneChip array comprised 59 860 bi-allelic markers, in 93 Thai families with multiple siblings, 195 individuals affected with tuberculosis. Genotyping revealed a region on chromosome 5q showing suggestive evidence of linkage with tuberculosis (Z(lr) statistics=3.01, logarithm of odds (LOD) score=2.29, empirical P-value=0.0005), and two candidate regions on chromosomes 17p and 20p by an ordered subset analysis using minimum age at onset of tuberculosis as the covariate (maximum LOD score=2.57 and 3.33, permutation P-value=0.0187 and 0.0183, respectively). These results imply a new evidence of genetic risk factors for tuberculosis in the Asian population. The significance of these ordered subset results supports a clinicopathological concept that immunological impairment in the disease differs between young and old tuberculosis patients. The linkage information from a specific ethnicity may provide unique candidate regions for the identification of the susceptibility genes and further help elucidate the immunopathogenesis of tuberculosis.

Indo-Oceanic Mycobacterium tuberculosis strains from Thailand associated with higher mortality.

SETTING: This study was conducted among tuberculosis (TB) patients in a highly endemic Thai province.OBJECTIVE: To evaluate the association between different Mycobacterium tuberculosis lineages and clinical characteristics, especially mortality.DESIGN: We enrolled 1,304 TB patients registered from 2002-2011 with culture isolates whose lineages were identified by specific regions of deletion. Data on mortality within 1 year of follow-up were extracted from the registration system and hospital records. Mortality-associated risk factors, including bacterial lineages, as independent variables were analysed using Cox regression models.RESULTS: Of 1,304 isolates, 521 (40.0%) and 582 (44.6%) belonged to Indo-Oceanic and East-Asian lineages, respectively. Indo-Oceanic strains significantly increased the mortality risk compared with East-Asian strains (adjusted hazard ratio [aHR] 1.42, 95%CI 1.02-1.99) or modern lineages (aHR 1.49, 95%CI 1.08-2.06) in the 172 patients who died within 1 year after TB diagnosis. The former also caused significantly higher mortality than modern lineages among patients who died within 6 months after TB diagnosis (aHR 1.62, 95%CI 1.12-2.35). No significant association was found between drug resistance and death.CONCLUSION: In Thailand, the Indo-Oceanic lineage of M. tuberculosis increased mortality risk compared with modern lineages or the East-Asian lineage, the latter being considered highly virulent in previous studies.

Strain-based HLA association analysis identified HLA-DRB1*09:01 associated with modern strain tuberculosis.

Tuberculosis (TB) occurs as a result of complex interactions between the host immune system and pathogen virulence factors. Human leukocyte antigen (HLA) class II molecules play an important role in the host immune system. However, no study has assessed the association between HLA class II genes and susceptibility to TB caused by specific strains. This study investigated the possible association of HLA class II genes with TB caused by modern and ancient Mycobacterium tuberculosis (MTB). The study included 682 patients with TB and 836 control subjects who were typed for HLA-DRB1 and HLA-DQB1 alleles. MTB strains were classified using a large sequence polymorphism typing method. Association analysis was performed using common HLA alleles and haplotypes in different MTB strains. HLA association analysis of patients infected with modern MTB strains showed significant association for HLA-DRB1*09:01 (odds ratio [OR] = 1.82; P-value = 9.88 × 10-4 ) and HLA-DQB1*03:03 alleles (OR = 1.76; P-value = 1.31 × 10-3 ) with susceptibility to TB. Haplotype analysis confirmed that these alleles were in strong linkage disequilibrium and did not exert an interactive effect. Thus, the results of this study showed an association between HLA class II genes and susceptibility to TB caused by modern MTB strains, suggesting the importance of strain-specific analysis to determine susceptibility genes associated with TB.

NAT2 slow acetylator associated with anti-tuberculosis drug-induced liver injury in Thai patients.

BACKGROUND: Anti-tuberculosis drug-induced liver injury (AT-DILI) is one of the most common forms of drug-induced liver injury (DILI) in high tuberculosis (TB) burden countries. Among anti-tuberculosis drugs, isoniazid is the main cause of hepatotoxicity in patients with AT-DILI. OBJECTIVE: To investigate the association of AT-DILI with N-acetyltransferase 2 (NAT2) genotype status in Thai TB patients. METHODS: We enrolled 53 patients diagnosed with AT-DILI and 85 patients who tolerated anti-tuberculosis treatment as controls. Acetylator status was determined based on the inferred NAT2 haplotypes from four common single-nucleotide polymorphisms (SNPs) in Thais using Sanger sequencing. RESULTS: Phenotype frequencies of the NAT2 acetylator in AT-DILI patients were respectively 71.7%, 22.6% and 5.7% for slow, intermediate and rapid acetylators. Among slow, intermediate, and rapid acetylators in treatment tolerant controls, phenotype frequencies were respectively 22.4%, 62.4% and 15.3%. Slow NAT2 acetylators demonstrated a significant association with risk of AT-DILI. The odds ratio of comparing slow NAT2 acetylator in DILI patients and tolerance was 8.80 (95%CI 4.01-19.31, P = 1.53 × 10-8). CONCLUSIONS: Slow acetylator status in the NAT2 genotype is a significant risk factor for DILI in Thai patients with TB. This evidence provides confirmatory data in support of the role of NAT2 in AT-DILI in the Thai population.

Evaluation of a novel line-probe assay for genotyping-based diagnosis of Mycobacterium tuberculosis in Thailand.

SETTING: The Supranational Tuberculosis Reference Laboratory (NTRL), Bangkok, and Chiangrai Prachanukroh Hospital, Chiangrai, Thailand OBJECTIVE: To evaluate the diagnostic performance of newly developed line-probe assay (LiPA) kits in tuberculosis (TB) endemic settings. DESIGN: LiPA kits were used to evaluate 404 clinical isolates of Mycobacterium species and 163 sputum samples in Thailand. RESULTS: LiPA kits were able to identify M. tuberculosis, M. avium, M. intracellulare and M. kansasii with 100% sensitivity and specificity when compared with the commercially available AccuProbe assay. Testing of the LiPA kits for their ability to detect mutations in clinical isolates resistant to anti-tuberculosis drugs such as rifampicin, isoniazid, pyrazinamide and fluoroquinolones showed that the assay had very high sensitivity (65.9-100%) and specificity (98.2-100%) compared with drug susceptibility testing and DNA sequencing. LiPA had a sensitivity of 75.0-85.7% and a specificity of 96.4-100% in testing clinical sputum samples. CONCLUSION: The novel LiPA kits have high sensitivity and specificity, and may enhance the rapid detection of first- and second-line anti-tuberculosis drug resistance, improving the selection of suitable chemotherapy agents to treat multidrug-resistant and extensively drug-resistant TB.

Association between apolipoprotein E genotypes and Parkinson's disease.

Previous studies on the association between apolipoprotein E (APOE) alleles and Parkinson's disease (PD) have shown contradictory results. A recent study showed that APOE is involved in a molecular pathway of α-synuclein-induced neurodegeneration. We therefore conducted the first Thai study on APOE genotypes in patients with PD. We analysed the frequencies of APOE genotypes in our case-control study of 155 patients with sporadic PD and 158 control participants. We identified a higher frequency of the APOE-ε2 allele among patients with PD than among controls (odds ratio=2.309, 95% confidence interval=1.111-4.799). Genetic association is a powerful tool for detecting disease susceptibility alleles, but there are many pitfalls to consider before claiming any association. The discrepancy among the results of the genetic association studies of APOE genotypes as a risk of susceptibility to PD emphasises that this association merits clarification by the study of a single large homogeneous population.