MDR tuberculosis--critical steps for prevention and control

Opinion review of drug resistant tuberculosis in West Africa: tackling the challenges for effective control

Drug-resistant (DR) tuberculosis (TB) is a major public health concern globally, complicating TB control and management efforts. West Africa has historically faced difficulty in combating DR-TB due to limited diagnostic skills, insufficient access to excellent healthcare, and ineffective healthcare systems. This has aided in the emergence and dissemination of DR Mycobacterium tuberculosis complex (MTBC) strains in the region. In the past, DR-TB patients faced insufficient resources, fragmented efforts, and suboptimal treatment outcomes. However, current efforts to combat DR-TB in the region are promising. These efforts include strengthening diagnostic capacities, improving access to quality healthcare services, and implementing evidence-based treatment regimens for DR-TB. Additionally, many West African National TB control programs are collaborating with international partners to scale up laboratory infrastructure, enhance surveillance systems, and promote infection control measures. Moreso, novel TB drugs and regimens, such as bedaquiline and delamanid, are being introduced to improve treatment outcomes for DR-TB cases. Despite these obstacles, there is optimism for the future of DR-TB control in West Africa. Investments are being made to improve healthcare systems, expand laboratory capacity, and support TB research and innovation. West African institutions are now supporting knowledge sharing, capacity building, and resource mobilization through collaborative initiatives such as the West African Network for TB, AIDS, and Malaria (WANETAM), the West African Health Organization (WAHO), and other regional or global partners. These efforts hold promise for improved diagnostics, optimized treatment regimens, and provide better patient outcomes in the future where drug-resistant TB in WA can be effectively controlled, reducing the burden of the disease, and improving the health outcomes of affected individuals.

Prevalence, Transmission and Genetic Diversity of Pyrazinamide Resistance Among Multidrug-Resistant Mycobacterium tuberculosis Isolates in Hunan, China

Background

China is a country with a burden of high rates of both TB and multidrug-resistant TB (MDR-TB). However, published data on pyrazinamide (PZA) resistance are still limited in Hunan province, China. This study investigated the prevalence, transmission, and genetic diversity of PZA resistance among multidrug-resistant Mycobacterium tuberculosis isolates in Hunan province.

Methods

Drug susceptibility testing (DST) with the Bactec MGIT 960 PZA kit and pyrazinamidase (PZase) testing were conducted on all 298 MDR clinical isolates. Moreover, 24-locus MIRU-VNTR and DNA sequencing of pncA, rpsA, and panD genes were conducted on 180 PZA-resistant (PZA-R) isolates.

Results

The prevalence of PZA resistance among MDR-TB strains reached 60.4%. Newly diagnosed PZA-R TB patients and clustered isolates with identical pncA, rpsA, and panD mutations showed that transmission of PZA-R isolates played a significant role in the formation of PZA-R TB. Ninety-eight mutation patterns were observed in the pncA among 180 PZA-R isolates, and seventy-one (72.4%) were point mutations. Twenty-four of these mutations are new, including 2 base substitutions (V93G and T153S) and 22 nucleotide deletions or insertions. The W119C was found in PZA-S isolates, on the other hand, F94L and V155A mutations were found in both PZA resistant and susceptible isolates with positive PZase activity, indicating that they were not associated with PZA resistance. This is not entirely in line with the WHO catalogue. Ten novel rpsA mutations were found in 10 PZA-R isolates, which all combined with mutations in pncA. Thus, it is unpredictable whether these mutations in rpsA can impact PZA resistance. No panD mutation was found in all PZA-R isolates.

Conclusion

DNA sequencing of pncA and PZase activity testing have great potential in predicting PZA resistance.

Unsuccessful treatment outcome and associated risk factors. A prospective study of DR-TB patients from a high burden country, Pakistan

INTRODUCTION

Tuberculosis (TB), a curable and preventable infectious disease, becomes difficult to treat if resistance against most effective and tolerable first line anti-TB drugs is developed. The objective of the present study was to evaluate the treatment outcomes and predictors of poor outcomes among drug-resistant tuberculosis (DR-TB) patients treated at a programmatic management unit of drug resistant tuberculosis (PMDT) unit, Punjab, Pakistan.

METHODS

This prospective observational study was conducted at a a PMDT unit in Multan, Punjab, Pakistan. A total of 271 eligible culture positive DR-TB patients enrolled for treatment at the study site between January 2016 and May 2017 were followed till their treatment outcomes were recorded. World Health Organization's (WHO) defined criteria was used for categorizing treatment outcomes. The outcomes of cured and treatment completed were collectively placed as successful outcomes, while death, lost to follow-up (LTFU) and treatment failure were grouped as unsuccessful outcomes. Multivariable binary logistic regression analysis was employed for getting predictors of unsuccessful treatment outcomes. A p-value <0.05 was considered statistically significant.

RESULTS

Of the 271 DR-TB patients analysed, nearly half (51.3%) were males. The patient's (Mean ± SD) age was 36.75 ± 15.69 years. A total of 69% patients achieved successful outcomes with 185 (68.2%) patients being cured and 2 (0.7%) completed therapy. Of the remaining 84 patients with unsuccessful outcomes, 48 (17.7%) died, 2 (0.7%) were declared treatment failure, 34 (12.5%) were loss to follow up. After adjusting for confounders, patients' age > 50 years (OR 2.149 (1.005-4.592) with p-value 0.048 and baseline lung cavitation (OR 7.798 (3.82-15.919) with p-value <0.001 were significantly associated with unsuccessful treatment outcomes.

CONCLUSIONS

The treatment success rate (69%) in the current study participants was below the target set by WHO (>75%). Paying special attention and timely intervention in patients with high risk of unsuccessful treatment outcomes may help in improving treatment outcomes at the study site.

Treatment cascade for patients with multidrug- or rifampicin-resistant tuberculosis and associated factors with patient attrition in southeastern China: a retrospective cohort study

OBJECTIVES

To address gaps in health services for multidrug- or rifampicin-resistant tuberculosis (MDR/RR-TB), a treatment cascade model was used to evaluate patient retention and attrition at each successive step required to achieve a successful treatment outcome.

METHODS

From 2015-2018, a four-step treatment cascade model was established in patients with confirmed MDR/RR-TB in southeast China. Step 1: diagnosis of MDR/RR-TB, step 2: Initiation of treatment, step 3: still under treatment at 6 month and step 4: cure or completion of MDR/RR-TB treatment, with each successive step including a gap that shows attrition of patients between steps. The retention and attrition of each step were graphed. Multi-variate logistic regression was carried out to further identify potential factors associated with the attrition.

RESULTS

In the treatment cascade consisting of 1752 MDR/RR-TB patients, the overall patient attrition rate was 55.8% (978/1752), with 28.0% (491/1752), 19.9% (251/1261), and 23.4% (236/1010) of patients attrition in the first, second, and third gap. Factors associated with MDR/RR-TB patients not initiating treatment included age ≥60 years (OR:2.875), and time for diagnosis ≥30 days (OR: 2.653). Patients who were diagnosed with MDR/RR-TB through rapid molecular test (OR: 0.517) and non-migrant residents of Zhejiang Province (OR: 0.273) both exhibited a lower likelihood of attrition during the treatment initiation phase. Meanwhile, old age (OR: 2.190) and non-resident migrants to the province were factors associated with not completing ≥ 6 months of treatment. Old age (OR: 3.883), retreatment (OR: 1.440), and time to diagnosis ≥30 days (OR: 1.626) were factors contributing to poor treatment outcomes.

CONCLUSION

Several programmatic gaps were identified in the MDR/RR-TB treatment cascade. Future policies should provide more comprehensive support for vulnerable populations to improve the care quality at each step.

Dimethyl itaconate is effective in host-directed antimicrobial responses against mycobacterial infections through multifaceted innate immune pathways

BACKGROUND

Itaconate, a crucial immunometabolite, plays a critical role in linking immune and metabolic functions to influence host defense and inflammation. Due to its polar structure, the esterified cell-permeable derivatives of itaconate are being developed to provide therapeutic opportunities in infectious and inflammatory diseases. Yet, it remains largely uncharacterized whether itaconate derivatives have potentials in promoting host-directed therapeutics (HDT) against mycobacterial infections. Here, we report dimethyl itaconate (DMI) as the promising candidate for HDT against both Mycobacterium tuberculosis (Mtb) and nontuberculous mycobacteria by orchestrating multiple innate immune programs.

RESULTS

DMI per se has low bactericidal activity against Mtb, M. bovis Bacillus Calmette-Guérin (BCG), and M. avium (Mav). However, DMI robustly activated intracellular elimination of multiple mycobacterial strains (Mtb, BCG, Mav, and even to multidrug-resistant Mtb) in macrophages and in vivo. DMI significantly suppressed the production of interleukin-6 and -10, whereas it enhanced autophagy and phagosomal maturation, during Mtb infection. DMI-mediated autophagy partly contributed to antimicrobial host defenses in macrophages. Moreover, DMI significantly downregulated the activation of signal transducer and activator of transcription 3 signaling during infection with Mtb, BCG, and Mav.

CONCLUSION

Together, DMI has potent anti-mycobacterial activities in macrophages and in vivo through promoting multifaceted ways for innate host defenses. DMI may bring light to new candidate for HDT against Mtb and nontuberculous mycobacteria, both of which infections are often intractable with antibiotic resistance.

Epidemiological features of tuberculosis infection in a rural prefecture of Japan from 2007 to 2018

This study aimed to investigate the epidemiological features of reported tuberculosis (TB) infections in a western prefecture (Nagasaki Prefecture) from 2007 to 2018, and to identify the high-risk group for TB infection. The characteristics of 12 years of reported TB infections from the Nagasaki Prefectural Informational Center of Infectious Diseases were summarized by median (interquartile range [IQR]) and proportion; the annual TB infections’ notification rate regarding sex/age was calculated accordingly. The diagnosis of TB infection was made according to clinic symptoms and laboratory examination. In total, 4364 TB infections were reported in 2007 and 2018, with a median age (IQR) of 74 (55–84) years. The majority of TB infections were male (52.6%, 2297/4364), > 65 years (65.8%, 2869/4364), and indigenous (98.1%, 4276/4364). Among active TB, 66.9% (1833/2740) had pulmonary TB, and 25.3% (694/2740) were diagnosed as extrapulmonary TB. The highest notification rate of TB infection was observed in the elderly male population (> 85 years). The annual notification rate of TB infections ranged between 19.4/and 34.0/100,000 for 12 years. The notification rates of TB infections were high in older people of both sexes, especially in men aged > 85. Therefore, appropriate interventions and health management are essential for TB control in (and with a focus on) the elderly population.

Multidrug-Resistant Tuberculosis in U.S.-Bound Immigrants and Refugees

Rationale: Approximately two-thirds of new cases of tuberculosis (TB) in the United States are among non-U.S.-born persons. Culture-based overseas TB screening in U.S.-bound immigrants and refugees has substantially reduced the importation of TB into the United States, but it is unclear to what extent this program prevents the importation of multidrug-resistant TB (MDR-TB). Objectives: To study the epidemiology of MDR-TB in U.S.-bound immigrants and refugees and to evaluate the effect of culture-based overseas TB screening in U.S.-bound immigrants and refugees on reducing the importation of MDR-TB into the United States. Methods: We analyzed data of immigrants and refugees who completed overseas treatment for culture-positive TB during 2015-2019. We also compared mean annual number of MDR-TB cases in non-U.S.-born persons within 1 year of arrival in the United States between 1996-2006 (when overseas screening followed a smear-based algorithm) and 2014-2019 (after full implementation of a culture-based algorithm). Results: Of 3,300 culture-positive TB cases identified by culture-based overseas TB screening in immigrants and refugees during 2015-2019, 122 (3.7%; 95% confidence interval [CI], 3.1-4.1) had MDR-TB, 20 (0.6%; 95% CI, 0.3-0.9) had rifampicin-resistant TB, 382 (11.6%; 95% CI, 10.5-12.7) had isoniazid-resistant TB, and 2,776 (84.1%; 95% CI, 82.9-85.4) had rifampicin- and isoniazid-susceptible TB. None were diagnosed with extensively drug-resistant TB. All 3,300 persons with culture-positive TB completed treatment overseas; of 70 and 11 persons who were treated overseas for MDR-TB and rifampicin-resistant TB, respectively, none were diagnosed with TB disease at postarrival evaluation in the United States. Culture-based overseas TB screening in U.S.-bound immigrants and refugees prevented 24.4 MDR-TB cases per year from arriving in the United States, 18.2 cases more than smear-based overseas TB screening. The mean annual number of MDR-TB cases among non-U.S.-born persons within 1 year of arrival in the United States decreased from 34.6 cases in 1996-2006 to 19.5 cases in 2014-2019 (difference of 15.1; P < 0.001). Conclusions: Culture-based overseas TB screening in U.S.-bound immigrants and refugees substantially reduced the importation of MDR-TB into the United States.

Reevaluating Rifampicin Breakpoint Concentrations for Mycobacterium tuberculosis Isolates with Disputed rpoB Mutations and Discordant Susceptibility Phenotypes

In this study, rifampicin resistance breakpoints based on MICs of disrupted rpoB mutants of Mycobacterium tuberculosis (MTB) were explored using the Mycobacteria Growth Indicator Tube (MGIT) system and microplate alamarBlue assay (MABA). Sixty-one MTB isolates with disputed low-level rifampicin resistance-associated rpoB mutations and 40 RIF-susceptible wild-type isolates were included. Among the 61 resistant isolates, 25 (41.0%) had MICs ≥2.0 mg/L via MABA, while 16 (26.2%) were identified as RIF resistant via MGIT. Epidemiological cut-off (ECOFF) values obtained using MABA and MGIT were 0.25 and 0.125 mg/L, respectively. Based on 0.125 mg/L as a tentative critical concentration (CC), MABA RIF resistance-detection sensitivity was 93.4%, prompting the reduction of the MGIT CC to 0.125 mg/L, given that only a single isolate (1.6%) with the borderline mutation would be misclassified as susceptible to RIF based on this CC. Based on DNA sequencing of RRDR as the gold standard, the diagnostic accuracy of MGIT (99.0%) was significantly higher than that of MABA (91.1%). MICs of Leu⁵¹¹Pro mutant isolates were negatively correlated with time to liquid culture positivity (TTP) in our analysis (R = 0.957, P < 0.01). In conclusion, our results demonstrated missed detection of a high proportion of rifampicin-resistant isolates based on the WHO-endorsed CC. Such missed detections would be avoided by reducing the optimal MGIT RIF CC to 0.125 mg/L. In addition, MGIT based on reduced CC outperformed MABA in detecting borderline RIF resistance, with MABA MIC results obtained for isolates with the same mutation correlating with MTB growth rate.

IMPORTANCE Tuberculosis (TB) is still one of the world's leading infectious disease killers. The early and accurate diagnosis of RIF resistance is necessary to deliver timely and appropriate treatment for TB patients and improve their clinical outcome. Actually, a proportion of MTB isolates with disputed rpoB mutations present a diagnostic dilemma between Xpert and phenotypical drug susceptibility testing (pDST). Recently, WHO reported a pragmatic approach by lowering critical concentration (CC) to boost sensitivity of resistance detection of pDST. Therefore, a detailed analysis of the association between RIF susceptibility and disrupted mutations within rpoB gene would lay a foundation to assess the diagnostic accuracy of pDST with lowering RIF CC. In this study, we aim to determine the MICs of MTB isolates with disrupted mutations by MGIT and microplate alamarBlue assay (MABA). We also aimed to determine the optimal breakpoints for MTB isolates with these mutations.

A recombinant selective drug-resistant M. bovis BCG enhances the bactericidal activity of a second-line anti-tuberculosis regimen

Drug-resistant tuberculosis (DR-TB) poses a new threat to global health; to improve the treatment outcome, therapeutic vaccines are considered the best chemotherapy adjuvants. Unfortunately, there is no therapeutic vaccine approved against DR-TB. Our study assessed the therapeutic efficacy of a recombinant drug-resistant BCG (RdrBCG) vaccine in DR-TB. We constructed the RdrBCG overexpressing Ag85B and Rv2628 by selecting drug-resistant BCG strains and transformed them with plasmid pEBCG or pIBCG to create RdrBCG-E and RdrBCG-I respectively. Following successful stability testing, we tested the vaccine's safety in severe combined immune deficient (SCID) mice that lack both T and B lymphocytes plus immunoglobulins. Finally, we evaluated the RdrBCG's therapeutic efficacy in BALB/c mice infected with rifampin-resistant M. tuberculosis and treated with a second-line anti-TB regimen. We obtained M. bovis strains which were resistant to several second-line drugs and M. tuberculosis resistant to rifampin. Notably, the exogenously inserted genes were lost in RdrBCG-E but remained stable in the RdrBCG-I both in vitro and in vivo. When administered adjunct to a second-line anti-TB regimen in a murine model of DR-TB, the RdrBCG-I lowered lung M. tuberculosis burden by 1 log10. Furthermore, vaccination with RdrBCG-I adjunct to chemotherapy minimized lung tissue pathology in mice. Most importantly, the RdrBCG-I showed almost the same virulence as its parent BCG Tice strain in SCID mice. Our findings suggested that the RdrBCG-I was stable, safe and effective as a therapeutic vaccine. Hence, the "recombinant" plus "drug-resistant" BCG strategy could be a useful concept for developing therapeutic vaccines against DR-TB.

Genetic composition and evolution of the prevalent Mycobacterium tuberculosis lineages 2 and 4 in the Chinese and Zhejiang Province populations

Background

There are seven human-adaptation lineages of Mycobacterium tuberculosis (Mtb). Tuberculosis (TB) dissemination is strongly influenced by human movements and host genetics. The detailed lineage distribution evolution of Mtb in Zhejiang Province is unknown. We aim to determine how different sub-lineages are transmitted and distributed within China and Zhejiang Province.

Methods

We analysed whole-genome sequencing data for a worldwide collection of 1154 isolates and a provincial collection of 1296 isolates, constructed the best-scoring maximum likelihood phylogenetic tree. Bayesian evolutionary analysis was used to calculate the latest common ancestor of lineages 2 and 4. The antigenic diversity of human T cell epitopes was evaluated by calculating the pairwise dN/dS ratios.

Results

Of the Zhejiang isolates, 964 (74.38%) belonged to lineage 2 and 332 (25.62%) belonged to lineage 4. The distributions of the sub-lineages varied across the geographic regions of Zhejiang Province. L2.2 is the most ancient sub-lineage in Zhejiang, first appearing approximately 6897 years ago (95% highest posterior density interval (HDI): 6513–7298). L4.4 is the most modern sub-lineage, first appearing approximately 2217 years ago (95% HDI: 1864–2581). The dN/dS ratios showed that the epitope and non-epitope regions of lineage 2 strains were significantly (P < 0.001) more conserved than those of lineage 4.

Conclusions

An increase in the frequency of lineage 4 may reflect its successful transmission over the last 20 years. The recent common ancestors of the sub-lineages and their transmission routes are relevant to the entry of humans into China and Zhejiang Province. Diversity in T cell epitopes may prevent Mycobacterium tuberculosis from being recognized by the immune system.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00673-7.

Costs of multidrug-resistant TB treatment in Finland and Estonia affected by the 2019 WHO guidelines

BACKGROUND:

Multidrug-resistant TB (MDR-TB) is a growing problem in the effort to end the global TB epidemic. In 2019, the WHO adopted a new standardised regiment for MDR-TB, consisting of only oral medications.

METHODS:

We estimated the impact of the new guidelines on the costs of TB treatment in Estonia and Finland. For both countries, the costs of the two most common new drug regimens were calculated, including drug costs, as well as care- and monitoring-related costs.

RESULTS:

In Turku, Finland, treatment costs with the old regimen were €178,714; this could either increase by 10% or decrease by 18%, depending on the duration of bedaquiline use (6 months vs. 20 months). In Estonia, treatment costs with the old regimen were €33,664, whereas the new regimens were associated with a 40% increase in overall costs.

CONCLUSIONS:

The 2019 WHO guidelines have led to significant changes in the costs of MDR-TB treatment in Finland and Estonia. These changes depend mostly on the drug regimen administered and on care-related practices, with important differences between countries and even within the same country due to local practices.

Trends in burden of multidrug-resistant tuberculosis in countries, regions, and worldwide from 1990 to 2017: results from the Global Burden of Disease study

Background

Antituberculosis-drug resistance is an important public health issue, and its epidemiological patterns has dramatically changed in recent decades. This study aimed to estimate the trends of multidrug-resistant tuberculosis (MDR-TB), which can be used to inform health strategies.

Methods

Data were collected from the Global Burden of Disease study 2017. The estimated annual percentage changes (EAPCs) were calculated to assess the trends of MDR-TB burden at global, regional, and national level from 1990 to 2017 using the linear regression model.

Results

Globally, the age-standardized rate (ASR) of MDR-TB burden including incidence, prevalence, death and disability-adjusted life years (DALYs) had pronounced increasing trends from 1990 to 1999, with the EAPCs were 17.63 [95% confidence interval (CI): 10.77–24.92], 17.57 (95% CI 11.51–23.95), 21.21 (95% CI 15.96–26.69), and 21.90 (95% CI 16.55–27.50), respectively. Particularly, the largest increasing trends were seen in areas and countries with low and low-middle sociodemographic index (SDI). However, the trends in incidence, prevalence, death and DALYs of MDR-TB decreased globally from 2000 to 2017, with the respective EAPCs were − 1.37 (95% CI − 1.62 to − 1.12), − 1.32 (95% CI − 1.38 to − 1.26), − 3.30 (95% CI − 3.56 to − 3.04) and − 3.32 (95% CI − 3.59 to − 3.06). Decreasing trends of MDR-TB were observed in most regions and countries, particularly that of death and DALYs in Slovenia were − 18.96 (95% CI − 20.82 to − 17.06) and -19.35 (95% CI − 21.10 to − 17.55), respectively. Whereas the pronounced increasing trends of MDR-TB occurred in Papua New Guinea, Singapore, and Australia.

Conclusions

The ASR of MDR-TB showed pronounced decreasing trends from 2000 to 2017. However, the MDR-TB burden remains a substantial challenge to the TB control globally, and requires effective control strategies and healthcare systems.

Global Fund contributions to health security in ten countries, 2014-20: mapping synergies between vertical disease programmes and capacities for preventing, detecting, and responding to public health emergencies

BACKGROUND

The Global Fund to Fight AIDS, Tuberculosis and Malaria is a robust vertical global health programme. The extent to which vertical programmes financially support health security has not been investigated. We, therefore, endeavoured to quantify the extent to which the budgets of this vertical programme support health security. We believe this is a crucial area of work as the global community works to combine resources for COVID-19 response and future pandemic preparedness.

METHODS

We examined budgets for work in Kenya, Uganda, Vietnam, Democratic Republic of the Congo, Guatemala, Guinea, India, Indonesia, Nigeria, and Sierra Leone from January, 2014 to December, 2020. These ten countries were selected because of the robustness of investments and the availability of data. Using the International Health Regulations Joint External Evaluation (JEE) tool as a framework, we mapped budget line items to health security capacities. Two researchers independently reviewed each budget and mapped items to the JEE. Budgets were then jointly reviewed until a consensus was reached regarding if an item supported health security directly, indirectly, or not at all. The budgets for the study countries were inputted into a single Microsoft Excel spreadsheet and line items that mapped to JEE indicators were scaled up to their respective JEE capacity. Descriptive analyses were then done to determine the total amount of money budgeted for activities that support health security, how much was budgeted for each JEE capacity, and how much of the support was direct or indirect.

FINDINGS

The research team reviewed 37 budgets. Budgets totalled US$6 927 284 966, and $2 562 063 054 (37·0%) of this mapped to JEE capacities. $1 330 942 712 (19·2%) mapped directly to JEE capacities and $1 231 120 342 (17·8%) mapped indirectly to JEE capacities. Laboratory systems, antimicrobial resistance, and the deployment of medical countermeasures and personnel received the most overall budgetary support; laboratory systems, antimicrobial resistance, and workforce development received the greatest amount of direct budgetary support.

INTERPRETATION

Over one-third of the Global Fund's work also supports health security and the organisation has budgeted more than $2 500 000 000 for activities that support health security in ten countries since 2014. Although these funds were not budgeted specifically for health security purposes, recognising how vertical programmes can synergistically support other global health efforts has important implications for policy related to health systems strengthening.

FUNDING

Resolve to Save Lives: An Initiative of Vital Strategies.

Preparation of Curdlan sulphate - Chitosan nanoparticles as a drug carrier to target Mycobacterium smegmatis infected macrophages

In this study, curdlan sulphate - chitosan nanoparticles were prepared through polyelectrolyte complexing at a mass ratio of 2:1 respectively. The curdlan was produced by fermentation with Agrobacterium sp. ATCC 31750, which was then sulphated to form the polyanionic polymer. A first-line tuberculosis drug, Rifampicin and a phytochemical, DdPinitol, were encapsulated into Curdlan Sulphate (CS) - Chitosan Nanoparticles (C) (CSC NPs) of size 205.41 ± 7.24 nm. The drug release kinetics followed a Weibull model with initial burst release (48 % Rifampicin and 27 % d-Pinitol within 6 h), followed by a sustained release. The prepared CSC: d-PIN + RIF NPs was cytocompatible and entered the M.smegmatis infected macrophages through multiple endocytic pathways including clathrin, caveolae and macropinocytosis. They showed superior bactericidal activity (2.4-2.7 fold) within 4 h when compared to free drug Rifampicin (1.6 fold). The drug encapsulated CSC: RIF suppressed the pro-inflammatory gene (TNF-α by 3.66 ± 0.19 fold) and CSC: d-PIN + RIF increased expression of the anti-inflammatory gene (IL-10 by 13.09 ± 0.47 fold). Expression of TGF- β1 gene also increased when treated with CSC: d-PIN + RIF (13.00 ± 0.19 fold) which provided the immunomodulatory activity of the encapsulated CSC NPs. Thus, curdlan sulphate - chitosan polyelectrolyte complex can be a potential nanocarrier matrix for intracellular delivery of multiple drugs.

Strengthening the response to drug-resistant TB in Pakistan: a practice theory-informed approach

Background

While Pakistan's Programmatic Management of Drug-Resistant Tuberculosis (PMDT) programme, launched in 2010, initially yielded significant gains in treatment outcomes, performance has since plateaued, and in some cases, regressed.

Objective

To critically investigate why the PMDT programme, well-structured and generously resourced as it is, could not improve upon or sustain this early success and to illustrate the use of practice theory as a framework to analyse functioning of health systems.

Method

A practice theory-informed ethnographic study was conducted at three PMDT clinics. The analysis drew on 9 months of participant observation and in-depth interviews with 13 healthcare providers and four managers.

Results

The PMDT model primarily focused on materialities such as infrastructure, drugs and numbers of people tested, and little on developing competencies of the PMDT staff to provide responsive care. This emphasis on materialities, and the linked focus of accountability processes, led the PMDT staff to create meanings that translated into prioritisation of certain easy-to-measure health-care practices at the expense of more difficult-to-measure practices related to responsiveness that are arguably also important for successful patient outcomes.

Conclusion

A narrow focus on measurable inputs, originating from priorities set at global and national levels, influence frontline care practices with negative consequences for quality of care and patient outcomes. Greater emphasis on improving routine process of care can enhance the effectiveness of the PMDT model of care. Practice theory provides a robust analytical framework to critically interrogate health systems and healthcare provision.

Discovery of thienothiazolocarboxamide analogues as novel anti-tubercular agent

In order to identify anti-tubercular agents with a novel scaffold, commercial libraries of small organic compounds were screened against a fluorescent strain of Mycobacterium tuberculosis H37Rv, using a dual phenotypic assay. Compounds were assessed against bacteria replicating in broth medium, as well as inside macrophages, and thienothiazolocarboxamide (TTCA) scaffold was identified as hit in both assays, with submicromolar inhibitory concentrations. Derivatives of TTCA were further synthesized and evaluated for their inhibitory effects on M.tuberculosis H37Rv. In the present study we report the structure-activity relationship of these TTCA derivatives. Compounds 28, 32 and 42 displayed good anti-tubercular activities, as well as favorable ADME and PK properties. Compound 42 exhibited excellent oral bioavailability in mice with high distribution to lungs, within 1 h. It was found to be efficacious in a dose dependent manner in a murine model of M. tuberculosis infection. Hence, compound 42 is now under evaluation as a potential lead candidate for treatment of tuberculosis.

Prediction of Mycobacterium tuberculosis pyrazinamidase function based on structural stability, physicochemical and geometrical descriptors

BACKGROUND

Pyrazinamide is an important drug against the latent stage of tuberculosis and is used in both first- and second-line treatment regimens. Pyrazinamide-susceptibility test usually takes a week to have a diagnosis to guide initial therapy, implying a delay in receiving appropriate therapy. The continued increase in multi-drug resistant tuberculosis and the prevalence of pyrazinamide resistance in several countries makes the development of assays for prompt identification of resistance necessary. The main cause of pyrazinamide resistance is the impairment of pyrazinamidase function attributed to mutations in the promoter and/or pncA coding gene. However, not all pncA mutations necessarily affect the pyrazinamidase function.

OBJECTIVE

To develop a methodology to predict pyrazinamidase function from detected mutations in the pncA gene.

METHODS

We measured the catalytic constant (kcat), KM, enzymatic efficiency, and enzymatic activity of 35 recombinant mutated pyrazinamidase and the wild type (Protein Data Bank ID = 3pl1). From all the 3D modeled structures, we extracted several predictors based on three categories: structural stability (estimated by normal mode analysis and molecular dynamics), physicochemical, and geometrical characteristics. We used a stepwise Akaike's information criterion forward multiple log-linear regression to model each kinetic parameter with each category of predictors. We also developed weighted models combining the three categories of predictive models for each kinetic parameter. We tested the robustness of the predictive ability of each model by 6-fold cross-validation against random models.

RESULTS

The stability, physicochemical, and geometrical descriptors explained most of the variability (R2) of the kinetic parameters. Our models are best suited to predict kcat, efficiency, and activity based on the root-mean-square error of prediction of the 6-fold cross-validation.

CONCLUSIONS

This study shows a quick approach to predict the pyrazinamidase function only from the pncA sequence when point mutations are present. This can be an important tool to detect pyrazinamide resistance.

Rising challenge of multidrug-resistant tuberculosis in China: a predictive study using Markov modeling

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) is on the rise in China. This study used a dynamic Markov model to predict the longitudinal trends of MDR-TB in China by 2050 and to assess the effects of alternative control measures.

METHODS

Eight states of tuberculosis transmission were set up in the Markov model using a hypothetical cohort of 100 000 people. The prevalence of MDR-TB and bacteriologically confirmed drug-susceptible tuberculosis (DS-TB+) were simulated and MDR-TB was stratified into whether the disease was treated with the recommended regimen or not.

RESULTS

Without any intervention changes to current conditions, the prevalence of DS-TB+ was projected to decline 67.7% by 2050, decreasing to 20 per 100 000 people, whereas that of MDR-TB was expected to triple to 58/100 000. Furthermore, 86.2% of the MDR-TB cases would be left untreated by the year of 2050. In the case where MDR-TB detection rate reaches 50% or 70% at 5% per year, the decline in prevalence of MDR-TB would be 25.9 and 36.2% respectively. In the case where treatment coverage was improved to 70% or 100% at 5% per year, MDR-TB prevalence in 2050 would decrease by 13.8 and 24.1%, respectively. If both detection rate and treatment coverage reach 70%, the prevalence of MDR-TB by 2050 would be reduced to 28/100 000 by a 51.7% reduction.

CONCLUSIONS

MDR-TB, especially untreated MDR-TB, would rise rapidly under China's current MDR-TB control strategies. Interventions designed to promote effective detection and treatment of MDR-TB are imperative in the fights against MDR-TB epidemics.

Differential Expression of Resistant and Efflux Pump Genes in MDR-TB Isolates

Background:

Numerous investigations demonstrate efflux as a worldwide bacterial mode of action which contributes to the resistance of drugs. The activity of antibiotics, which subjects to efflux, can be improved by the combined usage of efflux inhibitors. However, the efflux role to the overall levels of antibiotic resistance of clinical M. tuberculosis isolates is inadequately comprehended and is still disregarded by many.

Method:

Here, we assessed the contribution of resistant genes associated with isoniazid (INH) and rifampin (R) resistance to the levels of drug resistance in the (27) clinical isolates of MDR-TB. Additionally, the role of the resistance for six putative drug efflux pump genes to the antibiotics was investigated. The level of katG expression was down-regulated in 24/27 (88.88%) of MDR-TB isolates. Of the 27 MDR-TB isolates, inhA, oxyR-ahpC, and rpoB showed either overexpression or up-regulation in 8 (29.62%), 4 (14.81 %), and 24 (88.88%), respectively. Moreover, the efflux pump genes drrA, drrB, efpA, Rv2459, Rv1634, and Rv1250 were overexpressed under INH/RIF plus fresh pomegranate juice (FPJ) stress signifying the efflux pumps contribution to the overall levels of the resistance of MDR-TB isolates.

Conclusion:

These results displayed that the levels of drug resistance of MDR-TB clinical isolates are due to combination among drug efflux pump and the presence of mutations in target genes, a truth which is often ignored by the specialists of tuberculosis in favour of the almost undoubted significance of drug target- gene mutations for the resistance in M. tuberculosis.

A pre-clinical validation plan to evaluate analytical sensitivities of molecular diagnostics such as BD MAX MDR-TB, Xpert MTB/Rif Ultra and FluoroType MTB

Rapid diagnosis of tuberculosis (TB) and antibiotic resistances are imperative to initiate effective treatment and to stop transmission of the disease. A new generation of more sensitive, automated molecular TB diagnostic tests has been recently launched giving microbiologists more choice between several assays with the potential to detect resistance markers for rifampicin and isoniazid. In this study, we determined analytical sensitivities as 95% limits of detection (LoD₉₅) for Xpert MTB/Rif Ultra (XP-Ultra) and BD-MAX MDR-TB (BD-MAX) as two representatives of the new test generation, in comparison to the conventional FluoroType MTB (FT-MTB). Test matrices used were physiological saline solution, human and a mucin-based artificial sputum (MUCAS) each spiked with Mycobacterium tuberculosis in declining culture- and qPCR-controlled concentrations. With BD-MAX, XP-Ultra, and FT-MTB, we measured LoD₉₅^TB values of 2.1 cfu/ml (CI_95%: 0.9–23.3), 3.1 cfu/ml (CI_95%: 1.2–88.9), and 52.1 cfu/ml (CI_95%: 16.7–664.4) in human sputum; of 6.3 cfu/ml (CI_95%: 2.9–31.8), 1.5 cfu/ml (CI_95%: 0.7–5.0), and 30.4 cfu/ml (CI_95%: 17.4–60.7) in MUCAS; and of 2.3 cfu/ml (CI_95%: 1.1–12.0), 11.5 cfu/ml (CI_95%: 5.6–47.3), and 129.1 cfu/ml (CI_95%: 82.8–273.8) in saline solution, respectively. LoD₉₅ of resistance markers were 9 to 48 times higher compared to LoD₉₅^TB. BD-MAX and XP-Ultra have an equal and significantly increased analytical sensitivity compared to conventional tests. MUCAS resembled human sputum, while both yielded significantly different results than normal saline. MUCAS proved to be suitable for quality control of PCR assays for TB diagnostics.

Estimating treatment importance in multidrug-resistant tuberculosis using Targeted Learning: An observational individual patient data network meta-analysis

Persons with multidrug-resistant tuberculosis (MDR-TB) have a disease resulting from a strain of tuberculosis (TB) that does not respond to at least isoniazid and rifampicin, the two most effective anti-TB drugs. MDR-TB is always treated with multiple antimicrobial agents. Our data consist of individual patient data from 31 international observational studies with varying prescription practices, access to medications, and distributions of antibiotic resistance. In this study, we develop identifiability criteria for the estimation of a global treatment importance metric in the context where not all medications are observed in all studies. With stronger causal assumptions, this treatment importance metric can be interpreted as the effect of adding a medication to the existing treatments. We then use this metric to rank 15 observed antimicrobial agents in terms of their estimated add-on value. Using the concept of transportability, we propose an implementation of targeted maximum likelihood estimation, a doubly robust and locally efficient plug-in estimator, to estimate the treatment importance metric. A clustered sandwich estimator is adopted to compute variance estimates and produce confidence intervals. Simulation studies are conducted to assess the performance of our estimator, verify the double robustness property, and assess the appropriateness of the variance estimation approach.

Polymeric nanobiotics as a novel treatment for mycobacterial infections

Mycobacterium tuberculosis (Mtb) remains a major challenge to global health, made worse by the spread of multi-drug resistance. Currently, the efficacy and safety of treatment is limited by difficulties in achieving and sustaining adequate tissue antibiotic concentrations while limiting systemic drug exposure to tolerable levels. Here we show that nanoparticles generated from a polymer-antibiotic conjugate (‘nanobiotics’) deliver sustained release of active drug upon hydrolysis in acidic environments, found within Mtb-infected macrophages and granulomas, and can, by encapsulation of a second antibiotic, provide a mechanism of synchronous drug delivery. Nanobiotics are avidly taken up by infected macrophages, enhance killing of intracellular Mtb, and are efficiently delivered to granulomas and extracellular mycobacterial cords in vivo in an infected zebrafish model. We demonstrate that isoniazid (INH)-derived nanobiotics, alone or with additional encapsulation of clofazimine (CFZ), enhance killing of mycobacteria in vitro and in infected zebrafish, supporting the use of nanobiotics for Mtb therapy and indicating that nanoparticles generated from polymer-small molecule conjugates might provide a more general solution to delivering co-ordinated combination chemotherapy.

Evaluation of risk factors associated with drug-resistant tuberculosis in Yemen: data from centres with high drug resistance

Background

The World Health Organization (WHO) has reported that Yemen has a high burden of drug resistance and a worrying shortage of implemented diagnostic methods and drug treatment regimens. Therefore, in this study, we evaluated the risk factors associated with multidrug-resistant tuberculosis (MDR-TB) and explored the poor TB management in Yemen.

Methods

Between January 2014 and December 2016, we enrolled 135 patients with MDR-TB from drug resistance programmes at four major TB centres in Yemen for this prospective study. After exclusion of 20 patients, treatment outcomes were reported for 115 patients who attended a series of follow-ups.

Results

A total of 115 patients with MDR-TB were analysed from the four main TB centres in Yemen. Most patients (35.2%) were from the Aden TB centre. A success rate of 77.4% was reported for TB treatment. Of the 115 patients, 69.6% were resistant to two drugs, 18.3% were resistant to three drugs, and 12.2% were resistant to four drugs. During the intensive phase of treatment, 19 patients (16.5%) reported one or more adverse events. A multivariate logistic regression analysis revealed that a baseline body weight of ≤40 kg [p = 0.016; adjusted odds ratio (AOR) = 25.09], comorbidity (p = 0.049; AOR = 4.73), baseline lung cavities (p = 0.004; AOR = 15.32), and positive culture at the end of the intensive phase (p = 0.009; AOR = 8.83) were associated with the unsuccessful treatment outcomes in drug-resistant TB patients.

Conclusions

The success rate achieved after treatment was below the levels established by the WHO End TB Strategy (90%) and the United Nations Sustainable Development Goals (80%). Identification of risk factors associated with MDR-TB in Yemen is essential because it allows health workers to identify high-risk patients, especially in the absence of a second-line treatment or a laboratory diagnostic method. The Yemen National Tuberculosis Control Program should formulate new strategies for early detection of MDR-TB and invest in new programmes for MDR-TB management.

High-risk screening and detection of multidrug-resistant tuberculosis in two prefectures of China: a drug susceptibility surveillance-based secondary data analysis

BACKGROUND

In China, less than one-fifth of multidrug-resistant tuberculosis (MDR-TB) cases are detected. MDR-TB screening is conducted amongst the following five high-risk groups of TB patients: chronic cases, close contacts of MDR-TB patients, patients with treatment failure, relapsed and returned patients, and smear-positive patients at the end of the third month of initial treatment.

OBJECTIVE

To estimate the possibility of detecting MDR-TB cases if only the high-risk screening strategy is applied in China.

METHODS

A secondary analysis was applied to the surveillance-based longitudinal data of all sputum smear-positive TB patients in Prefecture E and Prefecture W of China from 2013 to 2015. The population attributable risk (PAR) was estimated using odds ratios for five risk factors/predictors and exposure proportions amongst all MDR-TB cases.

RESULTS

A total of 3513 TB patients (2807 from Prefecture E and 706 from Prefecture W) were included. Males accounted for 77.91% (2737/3513) of the patients. The average age was 52.5 ± 20.0 years old. Overall, 40.34% (71/176) of MDR-TB patients were from the five high-risk groups during the three-year study period. The detected proportion of MDR-TB cases using the high-risk screening strategy was significantly higher in Prefecture E than in Prefecture W. The PAR% for all five risk factors/predictors was 43.4% (95% CI: 24.6-61.7%), 49.9% (95% CI: 31.3-67.0%), and 30.3% (95% CI: 12.9-50.1%) in Prefecture E and 36.6% (95% CI: 10.4-64.5%), 13.3% (95% CI: -1.7-39.7%), and -82.5% (95% CI: -117.5--11.2%) in Prefecture W in 2013, 2014, and 2015, respectively. The PAR% for the five specific risk factors/predictors ranged from 0.4% (95% CI: -0.2-4.8%) to 21.0% (95% CI: 13.1-30.0%) in these two prefectures.

CONCLUSION

In general, a high-risk screening strategy would miss more than half of the MDR-TB patients because they do not belong to the five high-risk groups.

Time to appropriate treatment in patients with multidrug-resistant tuberculosis in South Korea: Are we still in 2010?

BACKGROUND

This study investigated the time to appropriate treatment and factors affecting late treatment initiation in patients with multidrug-resistant tuberculosis (MDR-TB) in South Korea.

METHODS

Data from patients with culture-confirmed pulmonary MDR-TB who received treatment at Pusan National University Hospital (PNUH) between January 2010 and July 2018 were reviewed retrospectively. Patients were divided into two groups according to the first institution they visited [patients who were transferred to PNUH after diagnosis of MDR-TB (Group A) and patients who were initially diagnosed with TB at PNUH (Group B)].

RESULTS

A total of 100 patients were included (53 in Group A and 47 in Group B). The percentage of patients in whom line probe assays (LPAs) for isoniazid and rifampin or Xpert MTB/RIF assays were performed was higher in Group B than in Group A [20.8 vs. 57.4% (P < 0.001) and 17.0 vs. 46.8% (P = 0.001), respectively]. The median time from the first visit to appropriate treatment initiation was longer in Group A (102.0 vs. 77.0 days, P = 0.002). However, a subgroup analysis of patients with pre-extensively or extensively drug-resistant TB (pre-XDR- or XDR-TB) revealed that the time to appropriate treatment did not differ between Groups A and B. Although the time to appropriate treatment decreased during the study period in both Groups A and B, this trend was not evident in patients with pre-XDR- or XDR-TB in Group B. Based on multivariate analyses, performance of LPAs for isoniazid and rifampin, performance of Xpert MTB/RIF assays, and the presence of uncomplicated MDR-TB were protective against delays in appropriate treatment initiation.

CONCLUSIONS

The time to appropriate treatment in patients with MDR-TB in South Korea was not acceptable, particularly for patients diagnosed outside of PNUH and for patients with pre-XDR- or XDR-TB. The use of rapid molecular drug susceptibility tests in various healthcare settings and introduction of second-line LPAs are required.

Evaluation of Polyphenolic Profile and Antibacterial Activity of Pomegranate Juice in Combination with Rifampin (R) against MDR-TB Clinical Isolates

BACKGROUND

The global rise of multi-drug resistant M. tuberculosis demands unconventional treatment to enhance the efficiency of current drugs. Punica granatum, which is known as pomegranate, is considered as a member of the Punicaceae family. Pomegranate, which is broadly documented for its activity against a wide spectrum of bacterial pathogens, deserves further scrutiny in this respect.

METHODS

Within this scope, this study investigated the effect of fresh pomegranate juice (FPJ) on the antibacterial activity of anti-tuberculosis drugs (Rifampin (R) and Isoniazid (INH)) against MDR-TB clinical isolates. The drug resistance profiles in M. tuberculosis clinical isolates were determined by susceptibility test using BACTEC MGIT 960 system. Four concentrations of fresh pomegranate juice (FPJ) (5%, 10%, 15%, and 20%) were evaluated in combination with R and INH at a dose range of (1.0 µg/ml) and (0.1 µg/ml), respectively against the MDR-TB isolates by the BACTEC MGIT 960 system. Moreover, this study scrutinized individual phenolic compounds of FPJ by using highperformance liquid chromatography (HPLC). The total polyphenols (TP), total flavonoid (TF), total anthocyanins content (TAC), and the antioxidant capacity were also assessed in FPJ.

RESULTS

Synergistic effects were observed between R and INH with FPJ against all tested strains. However, combination therapy of rifampin was more effective than isoniazid one. Therefore, the combination of R and FPJ has been used against (27) MDR-TB clinical isolates. 5% of FPJ plus R (1.0 µg/ml) were found to suppress the growth of one isolates for first group (INH and R resistant). However, 5% of FPJ demonstrated no synergistic impact with R for second (SM, R and INH resistant) and third group (INH, EMB, R and SM resistant). Moreover, 10% of FPJ and R (1.0 μg/ml) inhibited the bacterial growth of three isolates of first group and two isolates and one isolate for second and third group, respectively. Remarkably, 15% of FPJ plus R (1.0 µg/ml) appeared to inhibit the growth of MDR-TB isolates for all tested groups indicating a strong synergistic effect. Regarding H37RV, the complete inhibition of the bacterial growth was found to occur at 15% and 20% concentrations of FPJ only. Minimum inhibitory concentration (MIC) of FPJ ranged from (4% to13%) for first group and from (10% to15%) for second and third group. Thus, FPJ at 15% inhibited 100% of bacteria for all tested isolates (MIC100% =15%). Phenolic compounds identified in FPJ were gallic acid, benzoic acid, syringic, folic acid, pelargonidin, naringin+ellagic acid, naringenin, chlorogenic acid, caffeic acid, catechin, myricetin, kaempferol, quercetin, cyanidin-3-glycoside, p-cummaric acid, ferulic acid, and rutin. Total phenolic (TP), total flavonoid (TF), and total anthocyanin (TA) content were 841.5 mg/L, 638.73 mg RE/L, and 47.43 mg/L, accordingly.

CONCLUSION

Overall, FPJ displayed synergistic effect with R against MDR-TB clinical isolates due to its high content of polyphenol and antioxidant capability.

Does the Development of Vaccines Advance Solutions for Tuberculosis?

BACKGROUND

Mycobacterium tuberculosis (Mtb) is considered as one of the most efficacious human pathogens. The global mortality rate of TB stands at approximately 2 million, while about 8 to 10 million active new cases are documented yearly. It is, therefore, a priority to develop vaccines that will prevent active TB. The vaccines currently used for the management of TB can only proffer a certain level of protection against meningitis, TB, and other forms of disseminated TB in children; however, their effectiveness against pulmonary TB varies and cannot provide life-long protective immunity. Based on these reasons, more efforts are channeled towards the development of new TB vaccines. During the development of TB vaccines, a major challenge has always been the lack of diversity in both the antigens contained in TB vaccines and the immune responses of the TB sufferers. Current efforts are channeled on widening both the range of antigens selection and the range of immune response elicited by the vaccines. The past two decades witnessed a significant progress in the development of TB vaccines; some of the discovered TB vaccines have recently even completed the third phase (phase III) of a clinical trial.

OBJECTIVE

The objectives of this article are to discuss the recent progress in the development of new vaccines against TB; to provide an insight on the mechanism of vaccine-mediated specific immune response stimulation, and to debate on the interaction between vaccines and global interventions to end TB.

Trends in incidence and mortality of tuberculosis in Japan: a population-based study, 1997-2016

Japan is still a medium-burden tuberculosis (TB) country. We aimed to examine trends in newly notified active TB incidence and TB-related mortality in the last two decades in Japan. This is a population-based study using Japanese Vital Statistics and Japan Tuberculosis Surveillance from 1997 to 2016. We determined active TB incidence and mortality rates (per 100 000 population) by sex, age and disease categories. Joinpoint regression was applied to calculate the annual percentage change (APC) in age-adjusted mortality rates and to identify the years showing significant trend changes. Crude and age-adjusted incidence rates reduced from 33.9 to 13.9 and 37.3 to 11.3 per 100 000 population, respectively. Also, crude and age-adjusted mortality rates reduced from 2.2 to 1.5 and 2.8 to 1.0 per 100 000 population, respectively. Average APC in the incidence and mortality rates showed significant decline both in men (−6.2% and −5.4%, respectively) and women (−5.7% and −4.6%, respectively). Age-specific analysis demonstrated decreases in incidence and mortality rates for every age category, except for the incidence trend in the younger population. Although trends in active TB incidence and mortality rates in Japan have favourably decreased, the rate of decline is far from achieving TB elimination by 2035.

Factors affecting the utilization of Xpert MTB/RIF assay among TB clinic health workers in Addis Ababa

Introduction

The diagnostic accuracy of Xpert MTB/RIF is well documented but underutilization is a major challenge in most high burden countries. This appears to be linked with insufficient knowledge of health professionals of using the tool. However, this has not been well studied.

Objective

Our objective was to assess the knowledge of health professionals on Xpert MTB/RIF assay and associated factors in detecting TB/TB drug resistance.

Methods

An institution based cross–sectional study was conducted from April 4 to June 5, 2015, in Addis Ababa that involved 209 healthcare providers working in TB clinics. Structured questionnaire through self-administered interview technique was used to collect the data. We asked them about Xpert on whether they are aware of its place in TB diagnosis, when and for whom it shall be used, its role in treatment monitoring, result interpretation and patient's registration that are diagnosed by Xpert MTB/RIF. We used binary logistic regression analysis to identify associated factors. Odds ratio with 95% CI was computed to assess the strength of the associations.

Results

Of the 209 participants interviewed, the majority 151 (72.2%) were nurses. More than a half of the respondents 114 (54.6%) had poor knowledge. Health professionals with age above 35 years (AOR = 6.253, 95% CI (1.1995, 19.604)) and those who read the Xpert guideline (AOR = 4.231, 95% CI (2.011, 8.900)) were more likely to have good knowledge on Xpert.

Conclusion and recommendation

This study revealed that the overall magnitude of knowledge status was found to be low. Health workers above 35 years and those who read the guideline on Xpert had higher knowledge status on Xpert. Distribution of national guideline on Xpert and assigning experienced clinicians in TB DOTs clinics are recommended.

Performance of the GenoType MTBDRsl assay for the detection second-line anti-tuberculosis drug resistance

The rapid detection of drug-resistant tuberculosis (TB) is important to improve treatment outcomes and prevent disease transmission. The GenoType MTBDRsl assay (MTBDRsl assay) was developed to detect fluoroquinolone (FQ) and second-line injectable drug (SLID) resistance. The aim of this study was to evaluate the performance and clinical utility of MTBDRsl assay. We retrospectively reviewed patient medical records with MTBDRsl assay data between December 2011 and February 2017. MTBDRsl assay results were compared with that of phenotypic drug susceptibility testing. In addition, treatment outcomes were analyzed to evaluate the clinical utility of the MTBDRsl assay. Among 107 clinical isolates (84 cultured isolates and 23 sputum specimens), 85 (79.4%) were multidrug-resistant TB and 9 (8.4%) were extensively drug-resistant TB (XDR-TB). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MTBDRsl assay for detecting FQ resistance was 87.5%, 94.7%, 87.5%, 94.7%, and 92.5%, respectively. The sensitivity, specificity, PPV, NPV, and accuracy of MTBDRsl assay for detecting SLID resistance was 88.9%, 98.9%, 94.1%, 97.8%, and 97.2%, respectively. Novel drugs such as bedaquiline and linezolid were more commonly used in patients with FQ or SLID resistance detected by the MTBDRsl assay and, probably therefore, the treatment outcome was favorable irrespective of FQ or SLID resistance. The MTBDRsl assay could be used as a rule-in test to detect FQ and SLID resistance. By detecting FQ- and SLID-drug resistance rapidly, novel or repurposed drugs could be initiated earlier, suggesting that better treatment outcomes would be expected in patients with pre-XDR- and XDR-TB.

Predictors of unsuccessful interim treatment outcomes of multidrug resistant tuberculosis patients

Background

Interim treatment outcomes at 6-months for multidrug-resistant tuberculosis (MDR-TB) treatment are among the most basic performance monitoring and key evaluation indicators in the Stop and End TB strategy of the World Health Organization (WHO). Therefore, this study was conducted to evaluate the interim treatment outcomes of MDR-TB patients in Pakistan.

Methods

This study was conducted at the Programmatic Management Unit for Drug-resistance TB (PMDT) site of the National Tuberculosis Program (NTP), Pakistan. It is located in the Chest Disease Unit (CDU) of the Bahawal Victoria Hospital (BVH), Bahawalpur, Punjab, Pakistan. Data was collected between April 1, 2014 and December 31, 2015. The medical records, Electronic Nominal Recording Reporting System (ENRS) data and MRD-TB notification forms of the MDR-TB patients registered at the PMDT site were reviewed to obtain data. For reporting and calculation of interim treatment outcomes, standardized WHO methodology was adopted. Simple logistic regression analysis was used to examine the possible association between the dependent variable (i.e. unsuccessful interim treatment outcome) and selected socio-demographic and clinical variables.

Results

A total of 100 drug-resistant TB (DR-TB) patients (all types) were registered during the study period. Out of these, 80 were MDR-TB patients for whom interim results were available. Out of the 80 MDR-TB cases, 48 (60%) were classified under the successful interim treatment outcome category. The remaining 40% had unsuccessful 6-month treatment outcomes and 12 (15%) patients died, while nine (11.3%) were lost to follow-up by six months. The final predictors of unsuccessful interim treatment outcomes were; being resistant to ofloxacin (AOR 3.23, 95% CI 0.96–10.89; p-value = 0.04), having above normal baseline serum creatinine levels (AOR 6.49, 95% CI 1.39–30.27; p-value = 0.02), and being culture positive at the second month of treatment (AOR 6.94, 95% CI 2–24.12; p-value = 0.01).

Conclusions

Despite free treatment and programmatic efforts to ensure patient adherence, the high rate of unsuccessful interim treatment outcomes is concerning. The identified risk factors for unsuccessful interim treatment outcomes in the current study provides clinicians an opportunity to identify high-risk patients and ensure enhanced clinical management and greater treatment success rates.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2746-5) contains supplementary material, which is available to authorized users.

Collaborative public-private initiatives targeting multidrug-resistant tuberculosis (MDR-TB) supported by the Lilly MDR-TB Partnership: experiences in 2012-2016

Since 2003, the Lilly Foundation has supported the noncommercial Lilly MDR-TB Partnership, which involves more than 45 local, national, global, and nongovernmental organizations and governments. The aim of the Lilly MDR-TB Partnership is to achieve significant global impact on multidrug-resistant tuberculosis (MDR-TB) by addressing a series of important local health care needs in highly affected countries: China, India, Russia, and South Africa. The main focus of activities during 2012–2016 was on community needs in primary care. Supported projects seek to make meaningful and measurable progress toward global and national TB objectives. The partnership programs share an overall conceptual approach known as “research, report, advocate”, based on the piloting of novel approaches on a small scale, with outcomes assessed at early stages. The results are analyzed and communicated to governments, health-policy experts, and local and national stakeholders, including those in other countries facing similar MDR-TB challenges. For successful, cost-effective initiatives, the analysis is used as support when advocating for the scaling up of initiatives to regional or national levels. This article discusses representative examples of projects supported by the Lilly MDR-TB Partnership in the time period 2012–2016. The examples illustrate the potential for globally informed, locally designed primary-care collaborations to strengthen health care systems and support TB policies and offer observations to inform future health care public–private partnerships.

Performance of microscopic observation drug susceptibility for the rapid diagnosis of tuberculosis and detection of drug resistance in Bamako, Mali

OBJECTIVES

In Mali early detection and treatment of multidrug-resistant tuberculosis (MDR-TB) are still challenging due to the cost, time and/or complexity associated with regular tests. Microscopic Observation Drug Susceptibility (MODS) is a low-cost assay validated by WHO in 2010. It is a liquid-culture-based assay to detect the 'cording' characteristic of Mycobacterium tuberculosis complex and to assess susceptibility to both isoniazid and rifampicin defining multidrug-resistant tuberculosis (MDR-TB). In this study we aimed to evaluate the performance of MODS as diagnostic tool compared with a validated method-Mycobacteria Growth Indicator Tube/Antimicrobial Susceptibility Testing/Streptomycin, Isoniazid, Rifampicin and Ethambutol (MGIT/AST/SIRE).

METHODS AND RESULTS

Between January 2010 and October 2015 we included 98 patients with suspected TB in an observational cohort study. The sensitivity and specificity of MODS assay for detecting TB were respectively 94.12% and 85.71% compared with the reference MGIT/7H11 culture, with a Cohen κ coefficient of 0.78 (95% CI 0.517-1.043). The median time to culture positivity for MODS assay and MGIT (plus interquartile range, IQR) was respectively 8 days (IQR 5-11) and 6 days (IQR 5-6). In detecting patients with MDR-TB, the sensitivity and specificity of MODS assay were respectively 100% and 95.92%. The positive predictive value and negative predictive value were, respectively, 66.7% and 100%. The median turnaround times for obtaining MDR-TB results using MODS assay and MGIT/AST/SIRE was respectively 9 days and 35 days. Hence, the MODS assay rapidly identifies MDR-TB in Mali compared with the MGIT/AST/SIRE.

CONCLUSION

As an easy, simple, fast and affordable method, the MODS assay could significantly improve the management of TB.

Towards understanding the drivers of policy change: a case study of infection control policies for multi-drug resistant tuberculosis in South Africa

Background

Explaining policy change is one of the central tasks of contemporary policy analysis. In this article, we examine the changes in infection control policies for multi-drug resistant tuberculosis (MDR-TB) in South Africa from the time the country made the transition to democracy in 1994, until 2015. We focus on MDR-TB infection control and refer to decentralised management as a form of infection control. Using Kingdon’s theoretical framework of policy streams, we explore the temporal ordering of policy framework changes. We also consider the role of research in motivating policy changes.

Methods

Policy documents addressing MDR-TB in South Africa over the period 1994 to 2014 were extracted. Literature on MDR-TB infection control in South Africa was extracted from PubMed using key search terms. The documents were analysed to identify the changes that occurred and the factors driving them.

Results

During the period under study, five different policy frameworks were implemented. The policies were meant to address the overwhelming challenge of MDR-TB in South Africa, contextualised by high prevalence of HIV infection, that threatened to undermine public health programmes and the success of antiretroviral therapy rollouts. Policy changes in MDR-TB infection control were supported by research evidence and driven by the high incidence and complexity of the disease, increasing levels of dissatisfaction among patients, challenges of physical, human and financial resources in public hospitals, and the ideologies of the political leadership. Activists and people living with HIV played an important role in highlighting the importance of MDR-TB as well as exerting pressure on policymakers, while the mass media drew public attention to infection control as both a cause of and a solution to MDR-TB.

Conclusion

The critical factors for policy change for infection control of MDR-TB in South Africa were rooted in the socioeconomic and political environment, were supported by extensive research, and can be framed using Kingdon’s policy streams approach as an interplay of the problem of the disease, political forces that prevailed and alternative proposals.

Cost-effectiveness of bedaquiline in MDR and XDR tuberculosis in Italy

Objective: To evaluate the cost-effectiveness of bedaquiline plus background drug regimens (BR) for multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) in Italy. Methods: A Markov model was adapted to the Italian setting to estimate the incremental cost-effectiveness ratio (ICER) of bedaquiline plus BR (BBR) versus BR in the treatment of MDR-TB and XDR-TB over 10 years, from both the National Health Service (NHS) and societal perspective. Cost-effectiveness was evaluated in terms of life-years gained (LYG). Clinical data were sourced from trials; resource consumption for compared treatments was modelled according to advice from an expert clinicians panel. NHS tariffs for inpatient and outpatient resource consumption were retrieved from published Italian sources. Drug costs were provided by reference centres for disease treatment in Italy. A 3% annual discount was applied to both cost and effectiveness. Deterministic and probabilistic sensitivity analyses were conducted. Results: Over 10 years, BBR vs. BR alone is cost-effective, with ICERs of €16,639/LYG and €4081/LYG for the NHS and society, respectively. The sensitivity analyses confirmed the robustness of the results from both considered perspectives. Conclusion: In Italy, BBR vs. BR alone has proven to be cost-effective in the treatment of MDR-TB and XDR-TB under a range of scenarios.

Hospitalized care for MDR-TB in Port Harcourt, Nigeria: a qualitative study

BACKGROUND

In Nigeria multidrug-resistant tuberculosis (MDR-TB) is prevalent in 2.9% of new TB cases and 14% of retreatment cases, and the country is one of 27 with high disease burden globally. Patients are admitted and confined to one of ten MDR-TB treatment facilities throughout the initial 8 months of treatment. The perspectives of MDR-TB patients shared on social media and in academic research and those of providers are limited to experiences of home-based care. In this study we explored the views of hospitalised MDR-TB patients and providers in one treatment facility in Nigeria, and describe how their experiences are linked to accessibility of care and support services, in line with international goals. We aimed to explore the physical, social and psychological needs of hospitalized MDR TB patients, examine providers' perceptions about the hospital based model and discuss the model's advantages and disadvantages from the patient and the provider perspective.

METHODS

We conducted two gender distinct focus group discussions and 11 in-depth interviews with recently discharged MDR-TB patients from one MDR-TB treatment facility in Nigeria. We triangulated this with the views of four providers who played key roles in the management of MDR-TB patients via key informant interviews. Transcribed data was thematically analysed, using an iterative process to constantly compare and contrast emerging themes across the data set for deeper understanding of the full range of participants' views.

RESULTS

The study findings demonstrate the psycho-social impacts of prolonged isolation and the coping mechanisms of patients in the facility. The dislocation of patients from their normal social networks and the detachment between providers and patients created the need for interdependence of patients for emotional and physical support. Providers' fears of infection contributed to stigma and hindered accessibility of care and support services.

CONCLUSION

The current trend towards discharging patients after culture conversion would reduce the psycho-social impacts of prolonged isolation and potentially reduce the risk of occupational TB from prolonged contact with MDR-TB patients. Building on shared experiences and interdependence of MDR-TB patients in our study, innovative patient-centred support systems would likely help to reduce stigma, promote access to care and support services, and potentially impact on the outcome of treatment.

Cost-effectiveness of screening for active cases of tuberculosis in Flanders, Belgium

OBJECTIVE

To assess the cost-effectiveness of the tuberculosis screening activities currently funded by the Flemish government in Flanders, Belgium.

METHODS

After estimating the expenses for 2013-2014 of each of nine screening components - which include high-risk groups, contacts and people who are seeking tuberculosis consultation at a centre for respiratory health care - and the associated costs per active case of tuberculosis identified between 2007 and 2014, we compared the cost-effectiveness of each component. The applied perspective was that of the Flemish government.

FINDINGS

The three most cost-effective activities appeared to be the follow-up of asylum seekers who were found to have abnormal X-rays in initial screening at the Immigration Office, systematic screening in prisons and contact investigation. The mean costs of these activities were 5564 (95% uncertainty interval, UI: 3791-8160), 11 603 (95% UI: 9010-14 909) and 13 941 (95% UI: 10 723-18 201) euros (€) per detected active case, respectively. The periodic or supplementary initial screening of asylum seekers and the screening of new immigrants from high-incidence countries - which had corresponding costs of €51 813 (95% UI: 34 855-76 847), €126 236 (95% UI: 41 984-347 822) and €418 359 (95% UI: 74 975-1 686 588) - appeared much less cost-effective. Between 2007 and 2014, no active tuberculosis cases were detected during screening in the juvenile detention centres.

CONCLUSION

In Flanders, tuberculosis screening in juvenile detention centres and among new immigrants and the periodic or supplementary initial screening of asylum seekers appear to be relatively expensive ways of detecting people with active tuberculosis.

Transmission of multidrug-resistant Mycobacterium tuberculosis in Shanghai, China: a retrospective observational study using whole-genome sequencing and epidemiological investigation

BACKGROUND

Multidrug-resistance is a substantial threat to global elimination of tuberculosis. Understanding transmission patterns is crucial for control of the disease. We used a genomic and epidemiological approach to assess recent transmission of multidrug-resistant (MDR) tuberculosis and identify potential risk factors for transmission.

METHODS

We did a population-based, retrospective study of patients who tested positive for tuberculosis between Jan 1, 2009, and Dec 31, 2012, in Shanghai, China. We did variable-number-of-tandem-repeat genotyping and whole-genome sequencing of isolates. We measured strain diversity within and between genomically clustered isolates. Genomic and epidemiological data were combined to construct transmission networks.

FINDINGS

367 (5%) of 7982 patients with tuberculosis had MDR tuberculosis and 324 (88%) of these had isolates available for genomic analysis. 103 (32%) of the 324 MDR strains were in 38 genomic clusters that differed by 12 or fewer single nucleotide polymorphisms (SNPs), indicating recent transmission of MDR strains. Patients who had delayed diagnosis or were older than 45 years had high risk of recent transmission. 235 (73%) patients with MDR tuberculosis probably had transmission of MDR strains. Transmission network analysis showed that 33 (87%) of the 38 clusters accumulated additional drug-resistance mutations through emergence or fixation of mutations during transmission. 68 (66%) of 103 clustered MDR strains had compensatory mutations of rifampicin resistance.

INTERPRETATION

Recent transmission of MDR tuberculosis strains, with increasing drug-resistance, drives the MDR tuberculosis epidemic in Shanghai, China. Whole-genome sequencing can measure of the heterogeneity of drug-resistant mutations within and between hosts and help to determine the transmission patterns of MDR tuberculosis.

FUNDING

National Science and Technology Major Project, National Natural Science Foundation of China, and US National Insitutes of Health.

Bioanalysis of antitubercular drugs using liquid chromatography

Tuberculosis is a life threatening disease and second to HIV in terms of deaths due to infectious diseases. Drug resistance development of the first-line drugs is a major concern in the treatment of this disease. There is no comprehensive and critical review in the literature of the bioanalytical methods for the determination of anti-tubercular agents from last two decades. This work offers a detailed account on the liquid chromatographic methods reported in the literature for the estimation of various anti-tubercular drugs. Major emphasis is given to sample preparation process, sensitivity of method, chromatographic separation conditions and detection systems used in their bioanalysis.

Decreased Time to Treatment Initiation for Multidrug-Resistant Tuberculosis Patients after Use of Xpert MTB/RIF Test, Latvia

This test decreased time to treatment initiation by 66%–84%.

Few studies have examined whether the Xpert MTB/RIF test improves time to treatment initiation for persons with multidrug-resistant tuberculosis (MDR TB). We determined the impact of this test in Latvia, where it was introduced in 2010. After descriptive analyses of pulmonary MDR TB patients in Latvia during 2009–2012, time to treatment initiation was calculated, and univariate and multivariable accelerated failure time models were constructed. Univariate results showed strong evidence of an association between having rifampin-resistant TB detected by Xpert MTB/RIF and reduced time to treatment initiation versus the test not being used. A multivariable model stratifying by previous TB showed similar results. Our finding that in Latvia, time to treatment initiation was decreased for MDR TB cases that were rifampin-resistant TB by XpertMTB/RIF has implications for the use of this test in other settings with a high burden of MDR TB in which rifampin resistance is highly predictive of MDR TB.

WHO strategies for the programmatic management of drug-resistant tuberculosis

INTRODUCTION

Adequate management of drug-resistant tuberculosis (TB), including multidrug- (MDR) and extensively drug-resistant (XDR-) TB are within the priorities of the newly launched World Health Organization's End TB and Elimination Strategies.

AREAS COVERED

This manuscript presents the evidence on the MDR- /XDR-TB epidemiology and discusses how the five recommended priority actions can be applied at the programmatic level to tackle the epidemic: 1) prevent development of MDR-TB thorough high quality treatment of drug- susceptible TB; 2) expand rapid testing and detection of drug-resistant TB; 3) provide immediate access to effective treatment and proper care; 4) prevent transmission through infection control; 5) increase political commitment and financing. A non-systematic review using Pubmed was carried out in addition to additional relevant information taken from the abstracts of international scientific conferences. Expert commentary: Current and future control of MDR-TB significantly relies on the correct use of new diagnostics and new drugs from one side, and on the consistent application of the five core interventions at the programmatic level. In addition, it is mandatory to tackle the social determinants and socio-economic barriers favouring the MDR-TB, otherwise it will not be possible to reach the planned goals as well as TB Elimination.