From multidrug- to extensively drug-resistant tuberculosis: upward trends as seen from a 15-year nationwide study

An integrated computational approach towards novel drugs discovery against polyketide synthase 13 thioesterase domain of Mycobacterium tuberculosis

The acquired drug resistance by Mycobacterium tuberculosis (M. tuberculosis) to antibiotics urges the need for developing novel anti-M. tuberculosis drugs that possess novel mechanism of action. Since traditional drug discovery is a labor-intensive and costly process, computer aided drug design is highly appreciated tool as it speeds up and lower the cost of drug development process. Herein, Asinex antibacterial compounds were virtually screened against thioesterase domain of Polyketide synthase 13, a unique enzyme that forms α-alkyl β-ketoesters as a direct precursor of mycolic acids which are essential components of the lipid-rich cell wall of M. tuberculosis. The study identified three drug-like compounds as the most promising leads; BBB_26582140, BBD_30878599 and BBC_29956160 with binding energy value of - 11.25 kcal/mol, - 9.87 kcal/mol and - 9.33 kcal/mol, respectively. The control molecule binding energy score is -9.25 kcal/mol. Also, the docked complexes were dynamically stable with maximum root mean square deviation (RMSD) value of 3 Å. Similarly, the MM-GB\PBSA method revealed highly stable complexes with mean energy values < - 75 kcal/mol for all three systems. The net binding energy scores are validated by WaterSwap and entropy energy analysis. Furthermore, The in silico druglike and pharmacokinetic investigation revealed that the compounds could be suitable candidates for additional experimentations. In summary, the study findings are significant, and the compounds may be used in experimental validation pipeline to develop potential drugs against drug-resistant tuberculosis.

An overview of mechanism and chemical inhibitors of shikimate kinase

Tuberculosis is a highly infectious disease other than HIV/AIDS and it is one of the top ten causes of death worldwide. Resistance development in the bacteria occurs because of genetic alterations, and the molecular insights suggest that the accumulation of mutation in the individual drug target genes is the primary mechanism of multi-drug resistant tuberculosis. Chorismate is an essential structural fragment for the synthesis of aromatic amino acids and synthesized biochemically by a number of bacteria, including Mycobacterium tuberculosis, utilizing the shikimate pathway. This shikimate kinase is the newer possible target for the generation of novel antitubercular drug because this pathway is expressed only in mycobacterium and not in Mammals. The discovery and development of shikimate kinase inhibitors provide an opportunity for the development of novel selective medications. Multiple shikimate kinase inhibitors have been identified via insilico virtual screening and related protein-ligand interactions along with their in-vitro studies. These inhibitors bind to the active site in a similar fashion to shikimate. In the current review, we present an overview of the biology and chemistry of the shikimate kinase protein and its inhibitors, with special emphasis on the various active scaffold against the enzyme. A variety of chemically diversified synthetic scaffolds including Benzothiazoles, Oxadiazoles, Thiobarbiturates, Naphthoquinones, Thiazoleacetonitriles, Hybridized Pyrazolone derivatives, Orthologous biological macromolecule derivatives, Manzamine Alkaloids derivatives, Dipeptide inhibitor, and Chalcones are discussed in detail. These derivatives bind to the specific target appropriately proving their potential ability through different binding interactions and effectively explored as an effective and selective Sk inhibitor.Communicated by Ramaswamy H. Sarma.

Inteins as Drug Targets and Therapeutic Tools

Multidrug-resistant pathogens are of significant concern in recent years. Hence new antifungal and anti-bacterial drug targets are urgently needed before the situation goes beyond control. Inteins are polypeptides that self-splice from exteins without the need for cofactors or external energy, resulting in joining of extein fragments. Inteins are present in many organisms, including human pathogens such as Mycobacterium tuberculosis, Cryptococcus neoformans, C. gattii, and Aspergillus fumigatus. Because intein elements are not present in human genes, they are attractive drug targets to develop antifungals and antibiotics. Thus far, a few inhibitors of intein splicing have been reported. Metal-ions such as Zn²⁺ and Cu²⁺, and platinum-containing compound cisplatin inhibit intein splicing in M. tuberculosis and C. neoformans by binding to the active site cysteines. A small-molecule inhibitor 6G-318S and its derivative 6G-319S are found to inhibit intein splicing in C. neoformans and C. gattii with a MIC in nanomolar concentrations. Inteins have also been used in many other applications. Intein can be used in activating a protein inside a cell using small molecules. Moreover, split intein can be used to deliver large genes in experimental gene therapy and to kill selected species in a mixed population of microbes by taking advantage of the toxin-antitoxin system. Furthermore, split inteins are used in synthesizing cyclic peptides and in developing cell culture model to study infectious viruses including SARS-CoV-2 in the biosafety level (BSL) 2 facility. This mini-review discusses the recent research developments of inteins in drug discovery and therapeutic research.

Racemization-free synthesis of Nα-2-thiophenoyl-phenylalanine-2-morpholinoanilide enantiomers and their antimycobacterial activity

Nα-2-thiophenoyl-d-phenylalanine-2-morpholinoanilide (MMV688845, IUPAC: N-(1-((2-morpholinophenyl)amino)-1-oxo-3-phenylpropan-2-yl)thiophene-2-carboxamide) from the Pathogen Box^® library (Medicines for Malaria Ventures, MMV) is a promising lead compound for antimycobacterial drug development. Two straightforward synthetic routes to the title compound starting from phenylalanine or its Boc-protected derivative are reported. Employing Boc-phenylalanine as starting material and the T3P^® and PyBOP^® amide coupling reagents enables racemization-free synthesis, avoiding the need for subsequent separation of the enantiomers. The crystal structure of the racemic counterpart gives insight into the molecular structure and hydrogen bonding interactions in the solid state. The R-enantiomer of the title compound (derived from d-phenylalanine) exhibits activity against non-pathogenic and pathogenic mycobacterial strains, whereas the S-enantiomer is inactive. Neither of the enantiomers and the racemate of the title compound shows cytotoxicity against various mammalian cells.

Modeling Time to Death of Patients with Multidrug-Resistant Tuberculosis at Saint Peter's Specialized Hospital

BACKGROUND

Currently, the worldwide prevalence and incidence of multidrug-resistant tuberculosis (MDR-TB) is drastically increasing. The main objective of this study was modeling the time-to-death of patients with MDR-TB at St. Peter's Specialized Hospital, Addis Ababa, Ethiopia, by using various parametric shared frailty models.

STUDY DESIGN

A retrospective study design was used.

METHODS

The study population was TB patients with MDR at St. Peter's Specialized Hospital from January 2016 through December 2019. Exponential, Weibull, and log-normal were used as baseline hazard functions with the gamma and inverse Gaussian frailty distributions. All the models were compared based on Akaike's Information Criteria.

RESULTS

The overall median time to death was 11 months and 123 (33.5%) patients died. Patients who lived in rural areas had shorter survival time than those who lived in urban areas with an accelerated factor of 0.135 (P=0.002). Patients with a history of anti-TB drug consumption had a short survival time than those without such a history with an accelerated factor of 0.02 (P=0.001). The variability (heterogeneity) of time to death of patients in the region for the selected model (Weibull-inverse Gaussian shared frailty model) was =0.144 (P=0.027).

CONCLUSION

The MDR-TB patients with weight gain, khat and alcohol consumption, clinical complication of pneumothorax and pneumonia, extrapulmonary TB, and history of anti-TB drug consumption as well as those who lived in rural areas had a shorter survival time, compared to others. There was a significant heterogeneity effect in the St. Peter's Specialized Hospital. The best model for predicting the time to death of MDR-TB patients was Weibull-inverse Gaussian shared frailty model.

Bacteriophage gene products as potential antimicrobials against tuberculosis

Tuberculosis (TB) is recognised as one of the most pressing global health threats among infectious diseases. Bacteriophages are adapted for killing of their host, and they were exploited in antibacterial therapy already before the discovery of antibiotics. Antibiotics as broadly active drugs overshadowed phage therapy for a long time. However, owing to the rapid spread of antibiotic resistance and the increasing complexity of treatment of drug-resistant TB, mycobacteriophages are being studied for their antimicrobial potential. Besides phage therapy, which is the administration of live phages to infected patients, the development of drugs of phage origin is gaining interest. This path of medical research might provide us with a new pool of previously undiscovered inhibition mechanisms and molecular interactions which are also of interest in basic research of cellular processes, such as transcription. The current state of research on mycobacteriophage-derived anti-TB treatment is reviewed in comparison with inhibitors from other phages, and with focus on transcription as the host target process.

Molecular Targets Related Drug Resistance Mechanisms in MDR-, XDR-, and TDR-Mycobacterium tuberculosis Strains

Tuberculosis (TB) is a formidable infectious disease that remains a major cause of death worldwide today. Escalating application of genomic techniques has expedited the identification of increasing number of mutations associated with drug resistance in Mycobacterium tuberculosis. Unfortunately the prevalence of bacillary resistance becomes alarming in many parts of the world, with the daunting scenarios of multidrug-resistant tuberculosis (MDR-TB), extensively drug-resistant tuberculosis (XDR-TB) and total drug-resistant tuberculosis (TDR-TB), due to number of resistance pathways, alongside some apparently obscure ones. Recent advances in the understanding of the molecular/ genetic basis of drug targets and drug resistance mechanisms have been steadily made. Intriguing findings through whole genome sequencing and other molecular approaches facilitate the further understanding of biology and pathology of M. tuberculosis for the development of new therapeutics to meet the immense challenge of global health.

High Rates of Treatment Success in Pulmonary Multidrug-Resistant Tuberculosis by Individually Tailored Treatment Regimens

RATIONALE

We evaluated whether treatment outcomes for patients with multidrug-resistant and extensively drug-resistant tuberculosis can be substantially improved when sufficient resources for personalizing medical care are available.

OBJECTIVES

To describe the characteristics and outcomes of patients with pulmonary multidrug-resistant tuberculosis at the Otto Wagner Hospital in Vienna, Austria.

METHODS

We conducted a retrospective single-center study of patients initiated on treatment for multi-drug resistant tuberculosis between January 2003 and December 2012 at the Otto Wagner Hospital, Vienna, Austria. The records of patients with multidrug-resistant tuberculosis were reviewed for epidemiological, clinical, laboratory, treatment, and outcome data.

MEASUREMENTS AND MAIN RESULTS

Ninety patients with pulmonary multidrug-resistant tuberculosis were identified. The median age was 30 years (interquartile range, 26-37). All patients were of non-Austrian origin, and 70 (78%) came from former states of the Soviet Union. Thirty-nine (43%) patients had multidrug-resistant tuberculosis; 28 (31%) had additional bacillary resistance to at least one second-line injectable drug and 9 (10%) to a fluoroquinolone. Fourteen (16%) patients had extensively drug-resistant tuberculosis. Eighty-eight different drug combinations were used for the treatment of the 90 patients. Surgery was performed on 10 (11.1%) of the patients. Sixty-five (72.2%) patients had a successful treatment outcome, 8 (8.9%) defaulted, 3 (3.3%) died, 8 (8.9%) continued treatment in another country and their outcome was unknown, and 6 (6.7%) were still on therapy. None of the patients experienced treatment failure. Treatment outcomes for patients with extensively drug-resistant tuberculosis were similar to those of patients with multidrug-resistant tuberculosis.

CONCLUSIONS

High rates of treatment success can be achieved in patients with multidrug-resistant and extensively drug-resistant tuberculosis when individually tailored treatment regimens can be provided in a high-resource setting.

A quantitative and efficient approach to select MIRU-VNTR loci based on accumulation of the percentage differences of strains for discriminating divergent Mycobacterium tuberculosis sublineages

Although several optimal mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) loci have been suggested for genotyping homogenous Mycobacterium tuberculosis, including the Beijing genotype, a more efficient and convenient selection strategy for identifying optimal VNTR loci is needed. Here 281 M. tuberculosis isolates were analyzed. Beijing genotype and non-Beijing genotypes were identified, as well as Beijing sublineages, according to single nucleotide polymorphisms. A total of 22 MIRU-VNTR loci were used for genotyping. To efficiently select optimal MIRU-VNTR loci, we established accumulations of percentage differences (APDs) between the strains among the different genotypes. In addition, we constructed a minimum spanning tree for clustering analysis of the VNTR profiles. Our findings showed that eight MIRU-VNTR loci displayed disparities in h values of ≥0.2 between the Beijing genotype and non-Beijing genotype isolates. To efficiently discriminate Beijing and non-Beijing genotypes, an optimal VNTR set was established by adding loci with APDs ranging from 87.2% to 58.8%, resulting in the construction of a nine-locus set. We also found that QUB11a is a powerful locus for separating ST10s (including ST10, STF and STCH1) and ST22s (including ST22 and ST8) strains, whereas a combination of QUB11a, QUB4156, QUB18, Mtub21 and QUB26 could efficiently discriminate Beijing sublineages. Our findings suggested that two nine-locus sets were not only efficient for distinguishing the Beijing genotype from non-Beijing genotype strains, but were also suitable for sublineage genotyping with different discriminatory powers. These results indicate that APD represents a quantitative and efficient approach for selecting MIRU-VNTR loci to discriminate between divergent M. tuberculosis sublineages.

Changing prevalence and resistance patterns in children with drug-resistant tuberculosis in Mumbai

BACKGROUND

The prevalence of drug-resistant (DR) tuberculosis (TB) in children is increasing. Although, in India, multi-drug-resistant (MDR) TB rates have been relatively stable, the number of children with pre-extensively drug-resistant and extensively drug-resistant (XDR) TB is increasing.

AIM

To determine whether the prevalence of DR TB in children in Mumbai is changing and to study the evolving patterns of resistance.

METHODS

A retrospective study was undertaken in 1311 paediatric patients referred between April 2007 and March 2013 to the Paediatric TB clinic at B. J. Wadia Hospital for Children, Mumbai. Children were defined as having DR TB on the basis of drug susceptibility testing (DST) of Mycobacterium tuberculosis grown on culture of body fluids (in the case of extra pulmonary TB) or from gastric lavage/bronchi-alveolar lavage/sputum in patients with pulmonary TB or from DST of the contacts. The prevalence of DR TB was calculated and the type of DR was evaluated yearly and in the pre-2010 and post-2010 eras.

RESULTS

The overall prevalence of DR TB was 86 (6.6%) with an increase from 23 (5.6%) patients pre-2010 to 63 (7%) post-2010 (P = 0.40). Nine (10.4%) patients were diagnosed on the basis of contact with a parent with DR TB. Overall fluoroquinolone resistance increased from 9 (39.1%) pre-2010 to 59 (93.7%) post-2010 (P = 0.0001): moxifloxacin resistance increased from 2 (8.7%) to 29 (46%) (P = 0.0018) and ofloxacin resistance increased from 7 (30.4%) to 30 (47.6%) (P = 0.14). Ethionamide resistance also increased from 6 (26.1%) to 31 (49.2%) (P = 0.04), aminoglycoside resistance was one (4.3%) pre-2010 and 12 (19%) post-2010 (P = 0.17) and resistance remained virtually the same for both amikacin [0 pre-2010 and 6 (9.5%) after 2010] and kanamycin [one (4.3%) pre- and 6 (9.5%) post-2010]. Of the first-line drugs, resistance remained the same for isoniazid [23 (100%) to 61 (96.8%)], rifampicin [22 (95.7%) to 51 (80.9%),P = 0.17], pyrazinamide [15 (65.2%) to 35 (55.6%), P = 0.47], ethambutol [14 (60.9%) to 38 (60.3%), P = 1.00] and streptomycin [19 (82.6%) to 50 (79.4%), P = 1.00]. Resistance to PAS remained unchanged [2 (8.7%) to 5 (7.9%), P = 1.00].

CONCLUSION

There is increasing resistance to second-line anti-tuberculosis (ATT) drugs, particularly flouroquinolones and ethionamide. Hence, there is an urgent need to avoid the use of ATT drugs for non-tuberculous infection and to increase surveillance for DR TB in adults as MDR TB in children is usually through contact with an adult with infectious MDR TB.

The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis

Global tuberculosis incidence has declined marginally over the past decade, and tuberculosis remains out of control in several parts of the world including Africa and Asia. Although tuberculosis control has been effective in some regions of the world, these gains are threatened by the increasing burden of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. XDR tuberculosis has evolved in several tuberculosis-endemic countries to drug-incurable or programmatically incurable tuberculosis (totally drug-resistant tuberculosis). This poses several challenges similar to those encountered in the pre-chemotherapy era, including the inability to cure tuberculosis, high mortality, and the need for alternative methods to prevent disease transmission. This phenomenon mirrors the worldwide increase in antimicrobial resistance and the emergence of other MDR pathogens, such as malaria, HIV, and Gram-negative bacteria. MDR and XDR tuberculosis are associated with high morbidity and substantial mortality, are a threat to health-care workers, prohibitively expensive to treat, and are therefore a serious public health problem. In this Commission, we examine several aspects of drug-resistant tuberculosis. The traditional view that acquired resistance to antituberculous drugs is driven by poor compliance and programmatic failure is now being questioned, and several lines of evidence suggest that alternative mechanisms-including pharmacokinetic variability, induction of efflux pumps that transport the drug out of cells, and suboptimal drug penetration into tuberculosis lesions-are likely crucial to the pathogenesis of drug-resistant tuberculosis. These factors have implications for the design of new interventions, drug delivery and dosing mechanisms, and public health policy. We discuss epidemiology and transmission dynamics, including new insights into the fundamental biology of transmission, and we review the utility of newer diagnostic tools, including molecular tests and next-generation whole-genome sequencing, and their potential for clinical effectiveness. Relevant research priorities are highlighted, including optimal medical and surgical management, the role of newer and repurposed drugs (including bedaquiline, delamanid, and linezolid), pharmacokinetic and pharmacodynamic considerations, preventive strategies (such as prophylaxis in MDR and XDR contacts), palliative and patient-orientated care aspects, and medicolegal and ethical issues.

Molecular epidemiology of Mycobacterium tuberculosis complex in Brussels, 2010-2013

The tuberculosis (TB) incidence rate in Brussels-Capital Region is 3-fold higher than in Belgium as a whole. Eight years after the realization of initial prospective population-based molecular epidemiology investigations in this Region, a similar study over the period 2010–2013 was conducted. TB strains isolated from 945 patients were submitted to genotyping by standardized 24-locus-MIRU-VNTR typing and spoligotyping. The phylogenetic analysis showed that the LAM (16.7%) and Haarlem (15.7%) branches are the two most prevalent TB lineages circulating in Brussels. Analysis of the MDR subgroup showed an association with Beijing strains (39.9%) and patients native of Eastern Europe (40.7%). Genotyping detected 113 clusters involving 321 patients, giving a recent transmission index of 22.9%. Molecular-guided epidemiological investigations and routine surveillance activities revealed family transmission or social contact for patients distributed over 34 clusters. Most of the patients were foreign-born (75.7%). However, cluster analysis revealed only limited trans-national transmission. Comparison with the previous study shows a stable epidemiological situation except for the mean age difference between Belgian-born and foreign-born patients which has disappeared. This study confirms that molecular epidemiology has become an important determinant for TB control programs. However, sufficient financial means need to be available to perform all required epidemiological investigations.

"My Favourite Day Is Sunday": Community Perceptions of (Drug-Resistant) Tuberculosis and Ambulatory Tuberculosis Care in Kara Suu District, Osh Province, Kyrgyzstan

OBJECTIVES

Kyrgyzstan is one of the 27 high multidrug-resistant tuberculosis (MDR-TB) burden countries listed by the WHO. In 2012, Médecins Sans Frontières (MSF) started a drug-resistant tuberculosis (DR-TB) project in Kara Suu District. A qualitative study was undertaken to understand the perception of TB and DR-TB in order to improve the effectiveness and acceptance of the MSF intervention and to support advocacy strategies for an ambulatory model of care.

METHODS

This paper reports findings from 63 interviews with patients, caregivers, health care providers and members of communities. Data was analysed using a qualitative content analysis. Validation was ensured by triangulation and a 'thick' description of the research context, and by presenting deviant cases.

RESULTS

Findings show that the general population interprets TB as the 'lungs having a cold' or as a 'family disease' rather than as an infectious illness. From their perspective, individuals facing poor living conditions are more likely to get TB than wealthier people. Vulnerable groups such as drug and alcohol users, homeless persons, ethnic minorities and young women face barriers in accessing health care. As also reported in other publications, TB is highly stigmatised and possible side effects of the long treatment course are seen as unbearable; therefore, people only turn to public health care quite late. Most patients prefer ambulatory treatment because of the much needed emotional support from their social environment, which positively impacts treatment concordance. Health care providers favour inpatient treatment only for a better monitoring of side effects. Health staff increasingly acknowledges the central role they play in supporting DR-TB patients, and the importance of assuming a more empathic attitude.

CONCLUSIONS

Health promotion activities should aim at improving knowledge on TB and DR-TB, reducing stigma, and fostering the inclusion of vulnerable populations. Health seeking delays and adherence problems will be countered by further implementation of shortened treatment regimens. An ambulatory model of care is proposed when convenient for the patient; hospitalisation is favoured only when seen as more appropriate for the respective individual.

Targeting Mycobacterium tuberculosis Biotin Protein Ligase (MtBPL) with Nucleoside-Based Bisubstrate Adenylation Inhibitors

Mycobacterium tuberculosis (Mtb), responsible for both latent and symptomatic tuberculosis (TB), remains the second leading cause of mortality among infectious diseases worldwide. Mycobacterial biotin protein ligase (MtBPL) is an essential enzyme in Mtb and regulates lipid metabolism through the post-translational biotinylation of acyl coenzyme A carboxylases. We report the synthesis and evaluation of a systematic series of potent nucleoside-based inhibitors of MtBPL that contain modifications to the ribofuranosyl ring of the nucleoside. All compounds were characterized by isothermal titration calorimetry (ITC) and shown to bind potently with K(D)s ≤ 2 nM. Additionally, we obtained high-resolution cocrystal structures for a majority of the compounds. Despite fairly uniform biochemical potency, the whole-cell Mtb activity varied greatly with minimum inhibitory concentrations (MIC) ranging from 0.78 to >100 μM. Cellular accumulation studies showed a nearly 10-fold enhancement in accumulation of a C-2'-α analogue over the corresponding C-2'-β analogue, consistent with their differential whole-cell activity.

Drug-resistant tuberculosis in Eastern Europe: challenges and ways forward

Encouragingly, global rates of new tuberculosis (TB) cases have been falling since 2005, in line with the Millennium Development Goal targets; however, cases of multidrug-resistant (MDR-) and extensively drug-resistant TB (XDR-TB) have been increasing. Fifteen of the world's 27 high MDR- and XDR-TB burden countries are in the World Health Organization (WHO) European Region, of which 10 are in Eastern Europe (including Baltic and Caucasus countries). To address the MDR- and XDR-TB situation in the WHO European Region, a Consolidated Action Plan to Prevent and Combat M/XDR-TB (2011-2015) was developed for all 53 Member States and implemented in 2011. Since the implementation of the Action Plan, the proportion of MDR-TB appears largely to have levelled off among bacteriologically confirmed TB cases in high-burden countries with universal or near universal (>95%) first-line drug susceptibility testing (DST). The treatment success rate, however, continues to decrease. A contributing factor is the substantial proportion of MDR-TB cases that are additionally resistant to either a fluoroquinolone, a second-line injectable agent or both (XDR-TB); high-burden country proportions range from 12.6% to 80.4%. Proportions of XDR-TB range from 5% to 24.8%. Despite much progress in Eastern Europe, critical challenges remain as regards access to appropriate treatment regimens; patient hospitalisation; scale-up of laboratory capacity, including the use of rapid diagnostics and second-line DST; vulnerable populations; human resources; and financing. Solutions to these challenges are aligned with the Post-2015 Global TB strategy. As a first step, the global strategy should be adapted at regional and country levels to serve as a framework for immediate actions as well as longer-term ways forward.

Towards a European Framework to Monitor Infectious Diseases among Migrant Populations: Design and Applicability

There are limitations in our capacity to interpret point estimates and trends of infectious diseases occurring among diverse migrant populations living in the European Union/European Economic Area (EU/EEA). The aim of this study was to design a data collection framework that could capture information on factors associated with increased risk to infectious diseases in migrant populations in the EU/EEA. The authors defined factors associated with increased risk according to a multi-dimensional framework and performed a systematic literature review in order to identify whether those factors well reflected the reported risk factors for infectious disease in these populations. Following this, the feasibility of applying this framework to relevant available EU/EEA data sources was assessed. The proposed multidimensional framework is well suited to capture the complexity and concurrence of these risk factors and in principle applicable in the EU/EEA. The authors conclude that adopting a multi-dimensional framework to monitor infectious diseases could favor the disaggregated collection and analysis of migrant health data.

Declining trend of resistance to first-line anti-tubercular drugs in clinical isolates of Mycobacterium tuberculosis in a tertiary care north Indian hospital after implementation of revised national Tuberculosis control programme

Trends showing drug-resistance pattern are needed to understand direction of tuberculosis (TB) control programme. The drug-resistance pattern in state of Uttar Pradesh, India, is not documented. Here we are reporting the prevalence of multi-drug-resistant (MDR) and drug-resistant TB in previously treated cases of pulmonary tuberculosis following launch of revised national TB control programme (RNTCP) in whole of Uttar Pradesh. Isolates of Mycobacterium tuberculosis, from patients of pulmonary tuberculosis, who were treated with antitubercular drugs for more than 4 weeks, were tested for resistance to first-line drugs; streptomycin (S), Ethambutol (E), Rifampicin (R) and isoniazid (H) over a period of 4 years, 2009-2012. Total 2496 isolates of M. tuberculosis were tested, of which 1139 isolates (45.6%) were pan-sensitive and 370 (14.8%) were pan-resistant. Total 695 isolates (27.8%) were MDR. Maximum resistance was with Isoniazid (n=1069, 42.8%) followed by streptomycin (n=840, 33.7%), rifampicin (n=742, 29.7%), and ethambutol (n=613, 24.6%). A decline in number of MDR strains and individual drug resistance was seen. Total MDR strains in the year 2009, 2010, 2011 and 2012 were 35.6%, 30.8%, 26.7% and 22.8% respectively. The drug resistance pattern reported from time to time may vary substantially. The decline in drug resistance visible over last four years, after implementation of DOTS, appears promising.

Prevalence of Tuberculosis, Drug Susceptibility Testing, and Genotyping of Mycobacterial Isolates from Pulmonary Tuberculosis Patients in Dessie, Ethiopia

Due to their initially seemingly high cost, timely diagnosis and effective treatment of tuberculosis (TB) are usually hampered by lack or shortage of resources in many high TB burden countries. However, the benefits of effective treatment can eventually outweigh those of empirical treatment. Here, a cross-sectional study was conducted on samples from smear-positive new and retreatment TB patients. Data on sociodemographic and HIV status were collected. Samples were cultured for identification, conventional drug sensitivity testing, and molecular typing by deletion typing and spoligotyping. The results showed the youth were disproportionately affected. New cases were being treated following general treatment guidelines only. Monoresistance or multiple drug resistance was found in 16.5% of new patients. Spoligotyping showed that there were 44 patterns with families H3 and T1 (lineage 4) and CAS-Delhi (lineage 3) being dominant. Some rare patterns from lineage 7 were also found. Spoligotype pattern, HIV positivity, and previous treatment were not associated with drug resistance. That the vast majority of the patients were new cases and young and the large number of these patients with mono- or multiple drug resistance indicate that most TB cases are due to recent transmissions and that urgent actions are needed to curb the transmissions.

Totally drug-resistant tuberculosis and adjunct therapies

The first cases of totally drug-resistant (TDR) tuberculosis (TB) were reported in Italy 10 years ago; more recently, cases have also been reported in Iran, India and South Africa. Although there is no consensus on terminology, it is most commonly described as 'resistance to all first- and second-line drugs used to treat TB'. Mycobacterium tuberculosis (M.tb) acquires drug resistance mutations in a sequential fashion under suboptimal drug pressure due to monotherapy, inadequate dosing, treatment interruptions and drug interactions. The treatment of TDR-TB includes antibiotics with disputed or minimal effectiveness against M.tb, and the fatality rate is high. Comorbidities such as diabetes and infection with human immunodeficiency virus further impact on TB treatment options and survival rates. Several new drug candidates with novel modes of action are under late-stage clinical evaluation (e.g., delamanid, bedaquiline, SQ109 and sutezolid). 'Repurposed' antibiotics have also recently been included in the treatment of extensively drug resistant TB. However, because of mutations in M.tb, drugs will not provide a cure for TB in the long term. Adjunct TB therapies, including therapeutic vaccines, vitamin supplementation and/or repurposing of drugs targeting biologically and clinically relevant molecular pathways, may achieve better clinical outcomes in combination with standard chemotherapy. Here, we review broader perspectives of drug resistance in TB and potential adjunct treatment options.

Map the gap: missing children with drug-resistant tuberculosis

BACKGROUND

The lack of published information about children with multidrug-resistant tuberculosis (MDR-TB) is an obstacle to efforts to advocate for better diagnostics and treatment.

OBJECTIVE

To describe the lack of recognition in the published literature of MDR-TB and extensively drug-resistant TB (XDR-TB) in children.

DESIGN

We conducted a systematic search of the literature published in countries that reported any MDR- or XDR-TB case by 2012 to identify MDR- or XDR-TB cases in adults and in children.

RESULTS

Of 184 countries and territories that reported any case of MDR-TB during 2005-2012, we identified adult MDR-TB cases in the published literature in 143 (78%) countries and pediatric MDR-TB cases in 78 (42%) countries. Of the 92 countries that reported any case of XDR-TB, we identified adult XDR-TB cases in the published literature in 55 (60%) countries and pediatric XDR-TB cases for 9 (10%) countries.

CONCLUSION

The absence of publications documenting child MDR- and XDR-TB cases in settings where MDR- and XDR-TB in adults have been reported indicates both exclusion of childhood disease from the public discourse on drug-resistant TB and likely underdetection of sick children. Our results highlight a large-scale lack of awareness about children with MDR- and XDR-TB.

Evolutionary history and global spread of the Mycobacterium tuberculosis Beijing lineage

Mycobacterium tuberculosis strains of the Beijing lineage are globally distributed and are associated with the massive spread of multidrug-resistant (MDR) tuberculosis in Eurasia. Here we reconstructed the biogeographical structure and evolutionary history of this lineage by genetic analysis of 4,987 isolates from 99 countries and whole-genome sequencing of 110 representative isolates. We show that this lineage initially originated in the Far East, from where it radiated worldwide in several waves. We detected successive increases in population size for this pathogen over the last 200 years, practically coinciding with the Industrial Revolution, the First World War and HIV epidemics. Two MDR clones of this lineage started to spread throughout central Asia and Russia concomitantly with the collapse of the public health system in the former Soviet Union. Mutations identified in genes putatively under positive selection and associated with virulence might have favored the expansion of the most successful branches of the lineage.

Performance of REBA MTB-XDR to detect extensively drug-resistant tuberculosis in an intermediate-burden country

Extensively drug-resistant tuberculosis (XDR-TB) is a serious worldwide problem. The REBA MTB-XDR (REBA-XDR) was recently developed in Korea to detect resistance to ofloxacin, kanamycin, and streptomycin. The aim of this study is to evaluate the diagnostic accuracy of the REBA-XDR. We prospectively enrolled 104 patients with acid-fast bacilli smear-positive specimens between July 2010 and January 2013. Performance characteristics were compared between REBA-XDR and conventional drug-susceptibility testing. The sensitivity values of REBA-XDR for detecting resistance to ofloxacin, kanamycin, and streptomycin were 66.7%, 90.9%, and 60.0%, and the specificity values were 93.3%, 93.5%, and 85.4%, respectively. The positive predictive values were 62.5%, 62.5%, and 40.9%, and the negative predictive values were 94.3%, 98.9%, and 92.7%, respectively. Accuracy was 89.4%, 93.3%, and 81.7%, respectively. REBA-XDR seems to be a useful kit for "ruling in" XDR-TB in intermediate-burden countries, and especially useful for detecting kanamycin resistance.