Epidemiology of Drug-Resistant Tuberculosis

The anti-tubercular callyaerins target the Mycobacterium tuberculosis-specific non-essential membrane protein Rv2113

Spread of antimicrobial resistances urges a need for new drugs against Mycobacterium tuberculosis (Mtb) with mechanisms differing from current antibiotics. Previously, callyaerins were identified as promising anti-tubercular agents, representing a class of hydrophobic cyclopeptides with an unusual (Z)-2,3-di-aminoacrylamide unit. Here, we investigated the molecular mechanisms underlying their antimycobacterial properties. Structure-activity relationship studies enabled the identification of structural determinants relevant for antibacterial activity. Callyaerins are bacteriostatics selectively active against Mtb, including extensively drug-resistant strains, with minimal cytotoxicity against human cells and promising intracellular activity. By combining mutant screens and various chemical proteomics approaches, we showed that callyaerins target the non-essential, Mtb-specific membrane protein Rv2113, triggering a complex dysregulation of the proteome, characterized by global downregulation of lipid biosynthesis, cell division, DNA repair, and replication. Our study thus identifies Rv2113 as a previously undescribed Mtb-specific drug target and demonstrates that also non-essential proteins may represent efficacious targets for antimycobacterial drugs.

Molecular identification of multiple drug resistance (MDR) strain of Mycobacterium tuberculosis

BACKGROUND AND OBJECTIVES

Isoniazid and rifampin are the first -line drugs against Mycobacterium tuberculosis. Resistance to these important drugs is a serious threat to human public health. Therefore, this study aimed at molecular detection of resistance to these valuable drugs.

MATERIALS AND METHODS

In this descriptive cross-sectional study, 111 non - duplicated clinical samples including sputum and Bronchoalveolar lavage (BAL) samples were collected from patients referred to the Ardabil Health Center between 2017 and 2020. The samples were first examined by microscopic method, then their DNA was extracted using the boiling method. Specific primers and MAS-PCR method were employed for the detection resistance to isoniazid and rifampin drugs and identification of MDR strain.

RESULTS

of 111 specimens, 15.3% belonged to NTM. In total, the resistance rate to isoniazid and rifampin was 17% and 27% respectively while the resistance rate to isoniazid and rifampin among NTM was 61.54% and 38.46%.

CONCLUSION

In our study, the prevalence of resistance to isoniazid and rifampin among Mycobacterium tuberculosis complex(MTC) and non-tuberculous mycobacteria(NTM) was investigated using the MAS-PCR method. This work highlighted the high anti- tuberculosis resistance rate among NTM compared to MTC strains.

Multidrug-resistant tuberculosis control in Rwanda overcomes a successful clone that causes most disease over a quarter century

SUMMARY BACKGROUND

Multidrug-resistant (MDR) tuberculosis (TB) poses an important challenge in TB management and control. Rifampicin resistance (RR) is a solid surrogate marker of MDR-TB. We investigated the RR-TB clustering rates, bacterial population dynamics to infer transmission dynamics, and the impact of changes to patient management on these dynamics over 27 years in Rwanda.

METHODS

We analysed whole genome sequences of a longitudinal collection of nationwide RR-TB isolates. The collection covered three important periods: before programmatic management of MDR-TB (PMDT; 1991-2005), the early PMDT phase (2006-2013), in which rifampicin drug-susceptibility testing (DST) was offered to retreatment patients only, and the consolidated phase (2014-2018), in which all bacteriologically confirmed TB patients had rifampicin DST done mostly via Xpert MTB/RIF assay. We constructed clusters based on a 5 SNP cut-off and resistance conferring SNPs. We used Bayesian modelling for dating and population size estimations, TransPhylo to estimate the number of secondary cases infected by each patient, and multivariable logistic regression to assess predictors of being infected by the dominant clone.

RESULTS

Of 308 baseline RR-TB isolates considered for transmission analysis, the clustering analysis grouped 259 (84.1%) isolates into 13 clusters. Within these clusters, a single dominant clone was discovered containing 213 isolates (82.2% of clustered and 69.1% of all RR-TB), which we named the "Rwanda Rifampicin-Resistant clone" (R3clone). R3clone isolates belonged to Ugandan sub-lineage 4.6.1.2 and its rifampicin and isoniazid resistance were conferred by the Ser450Leu mutation in rpoB and Ser315Thr in katG genes, respectively. All R3clone isolates had Pro481Thr, a putative compensatory mutation in the rpoC gene that likely restored its fitness. The R3clone was estimated to first arise in 1987 and its population size increased exponentially through the 1990s', reaching maximum size (∼84%) in early 2000 s', with a declining trend since 2014. Indeed, the highest proportion of R3clone (129/157; 82·2%, 95%CI: 75·3-87·8%) occurred between 2000 and 13, declining to 64·4% (95%CI: 55·1-73·0%) from 2014 onward. We showed that patients with R3clone detected after an unsuccessful category 2 treatment were more likely to generate secondary cases than patients with R3clone detected after an unsuccessful category 1 treatment regimen.

CONCLUSIONS

RR-TB in Rwanda is largely transmitted. Xpert MTB/RIF assay as first diagnostic test avoids unnecessary rounds of rifampicin-based TB treatment, thus preventing ongoing transmission of the dominant R3clone. As PMDT was intensified and all TB patients accessed rifampicin-resistance testing, the nationwide R3clone burden declined. To our knowledge, our findings provide the first evidence supporting the impact of universal DST on the transmission of RR-TB.

Performance of Nucleic Acid Amplification Tests in Patients with Presumptive Pulmonary Tuberculosis in Taiwan

INTRODUCTION

Several nucleic acid amplification tests (NAATs) for detection of Mycobacterium tuberculosis (TB) complex (MTBC) are available in Taiwan; however, their performances may differ and have not been extensively evaluated. Therefore, we aimed to explore the accuracy of NAATs overall followed by comparison between platforms commonly used in Taiwan.

METHODS

This study enrolled presumptive pulmonary TB patients with NAATs throughout Taiwan. The diagnostic performance of smear microscopy and NAATs was assessed using sputum culture as a reference standard. To investigate the performance of NAATs in excluding non-tuberculous mycobacteria (NTM), we quantified the false-positive proportion of NAATs in patients infected with NTM.

RESULTS

Of the 4126 enrollees, 860 (20.8%) had positive NAATs. The sensitivity and specificity of NAATs were 83.2% and 96.7%, respectively, compared to 81.5% and 55.3% for smear. There was no significant difference in sensitivity between the NAATs and smear; however, the specificity of smear was significantly lower than that of the NAATs [difference 41.4%, 95% confidence interval (CI) 39.6-43.2%]. There was no significant difference in sensitivity among Roche Cobas Amplicor Mycobacterium tuberculosis assay (Amplicor), Xpert MTB/RIF assay (Xpert) and in-house polymerase chain reaction (in-house PCR) (82.2% versus 83.8% versus 82.4%); however, in-house PCR was significantly less specific than Amplicor (difference 5.3%, 95% CI 2.4-8.2%) and Xpert (difference 5.8%, 95% CI 3.1-8.5%). The sensitivity of NAATs among smear-negative cases was 33.1% (95% CI 26.0-40.3%). In-house PCR had a significantly higher false-positive rate among specimens that were culture positive for NTM than Amplicor (7.7% versus 0.3%; difference 7.4%, 95% CI 3.4-11.5%) and Xpert (7.7% versus 0.7%; difference 7.0%, 95% CI 2.9-11.0%).

CONCLUSION

The NAATs overall had a relatively high sensitivity and specificity in detecting MTBC while Amplicor and Xpert performed better than in-house PCR in excluding NTM. Our findings will be useful for the development of national policy.

Comorbid diseases and conditions in people with HIV in the UK

OBJECTIVES

This study aimed to characterize the risk of people living with HIV (PLHIV) in the UK progressing to pre-specified HIV-associated comorbidities, compared with matched, HIV-negative controls.

METHODS

Primary and secondary care records from the Clinical Practice Research Datalink (CPRD) and linked Hospital Episode Statistics (HES) were used to identify PLHIV, and a matched cohort from the HIV-negative population. Kaplan Meier curves and Cox proportional hazard models were used to evaluate the risk of developing comorbidities including central nervous system (CNS) disorders, end-stage renal disease, osteoporosis, diabetes, cardiovascular disease (CVD), hypertension, stroke and cancer.

RESULTS

A total of 2945 PLHIV were matched to a cohort of 5890 HIV-negative controls. PLHIV demonstrated an increased hazard ratio (HR) for time to development of incident sleep disorders, depression, osteoporosis, stroke, cancer and renal disease when compared with their matched HIV-negative control. The HRs for anxiety, hypertension, diabetes and CVD were not significantly increased.

CONCLUSIONS

PLHIV in the UK were at a higher risk of developing a number of comorbid conditions, highlighting the need for regular attendance of health reviews such as the annual health reviews recommended by the British HIV Associations (BHIVA) quality standard for care, which are currently not uniformly conducted.

In vitro activity of bedaquiline against Mycobacterium avium complex

Introduction. Nontuberculous mycobacteria (NTM) are widespread in the environment and can cause various diseases in humans, especially immunocompromised patients.Hypothesis. Treatment of diseases caused by NTM is a complicated issue, mainly due to the resistance of the pathogen to most antimicrobial agents. Bedaquiline (Bdq) is now widely used for the treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB).Aim. The main goal of our study was to evaluate the activity of Bdq against Mycobacterium avium complex (MAC), the most common species among NTM.Methodology. A total of 166 MAC cultures (124 Mycobacterium avium and 42 Mycobacterium intracellulare) were studied. The minimum inhibitory concentrations (MICs) of Bdq for M. avium and M. intracellulare were obtained by twofold serial dilutions in the Middlebrook 7H9 medium. MIC ranges were determined and the MIC₅₀, MIC₉₀ and ECOFF values were obtained.Results. The MICs in respect of M. avium ranged from 0.003 to 1.0 µg ml^-1; those for M. intracellulare ranged from 0.003 to 0.5 µg ml^-1. The Bdq MIC₅₀ and MIC₉₀ values were found to be 0.015 and 0.12 µg ml^-1 , respectively, for M. avium and 0.007 and 0.06 µg ml^-1, respectively, for M. intracellulare. The tentative ECOFF values for M. avium and M. intracellulare were 0.12 and 0.06 µg ml^-1, respectively.Conclusion. The main bedaquiline susceptibility parameters for MAC strains isolated in the Moscow region were determined.

Oral anti-tuberculosis drugs: An urgent medication reconciliation at hospitals in Indonesia

Background: Four oral anti-tuberculosis drugs are conceived to be the most effective ones to eradicate Mycobacterium tuberculosis bacteria and to obviate the resistant organisms. However, the patients’ adherence and medication discrepancies are obstacles to achieving the goal. This study aimed to define the anti-tuberculosis drugs used in the hospitals and to detect the discrepancies in the continuity of the tuberculosis treatment.

Design and Methods: This retrospective cross-sectional study was based on medical records of adult patients, and was conducted in two district tertiary care hospitals. Only 35 out of 136 patient records from Hospital A and 33 out of 85 records from Hospital B met the inclusion criteria.

Results: The most common systemic anti-infective drugs in the study were ceftriaxone (51.80 DDD/100 patient-days) used in Hospital A and isoniazid (59.53 DDD/100 patient-days) used in Hospital B. The number of rifampicin prescriptions was less than that of isoniazid. Each patient received an average of two DDD/100 patient-days, which is an under dosage for an effective treatment.

Conclusion: This study showed a medication discrepancy of tuberculosis therapy. Tuberculosis patients’ medical histories are not under the full attention of treating physicians wherever they are admitted. Thus, medication reconciliation is needed to accomplish the goal of a Tuberculosis-free world in 2050.

Incidence Density and Predictors of Multidrug-Resistant Tuberculosis Among Individuals With Previous Tuberculosis History: A 15-Year Retrospective Cohort Study

Background: To date, too little attention has been paid to monitoring and estimating the risk of incident multidrug-resistant tuberculosis (MDR-TB) among individuals with a previous tuberculosis history (PTBH). The purpose of this study was to assess the incidence of and risk factors for MDR-TB in those individuals.

Methods: Between 2005 and 2020, a large, retrospective, population-based cohort study was performed in Hangzhou, China. A multivariable Cox regression model was used to evaluate independent predictors of incident MDR-TB among individuals with PTBH.

Results: The incidence density of MDR-TB was 22.6 per 1,000 person-years (95% confidence level and an interval of 20.9–24.3) for individuals with PTBH. The incidence of MDR-TB increased significantly in individuals who

• were under 60 years old.

• were male.

• had a history of direct contact.

• came from low-income families.

• worked in high-risk occupations.

• lived in rural areas.

• had a retreatment TB history.

• had an unfavorable outcome in their previous treatment (P < 0.05).

In addition, we found that the following factors were significantly linked to the MDR-TB risk among individuals with PTBH (P < 0.05):

• sociodemographic factors such as the 21–30 and 31–40 year age groups, or a history of direct contact.

• clinical factors like passive modes of TB case finding (PMTCF), human immunodeficiency virus infection, unfavorable treatment outcomes, retreated TB history, non-standardized treatment regimens of retreatment TB patients, and duration of pulmonary cavities (DPC).

• microbiological factors, such as duration of positive sputum culture.

We also found that the 21–30 year age group, low family income, and PMTCF were significantly linked to incident MDR-TB only in males with PTBH, whilst the 41–50 year age group, extended treatment course, and DPC were significantly associated with female MDR-TB only.

Conclusion: The incidence of MDR-TB was high, with a higher rate among subjects with a history of direct contact and unfavorable treatment outcomes. There was a gender difference in the incidence density and risk factors of MDR-TB among individuals with PTBH. Long-term monitoring and gender-specific risk-factor modifications should be given to individuals with PTBH.

Association of psychological status with first diagnosed pulmonary tuberculosis in men

The aim. Assessment of the initial psychological status of men with first diagnosed pulmonary tuberculosis and the study of its associations with the clinical course of the disease. Materials and methods. The study involved 54 men with first diagnosed pulmonary tuberculosis. Patients had a dynamic complex clinical, laboratory and instrumental examination with an assessment of the psychological status according to the State-Trait Anxiety Inventory (STAI) and the Beck Depression Inventory (BDI). Results. The evaluating of initial psychological status in patients with first diagnosed pulmonary tuberculosis, depressive states of varying severity were found in 47.05 % of patients, moderate state anxiety – in 74.51 % of patients, moderate trait anxiety – in 35.29 %. We revealed associations of the levels of anxiety and depression with the degree of bacterial excretion and the duration of the intensive phase of therapy. Conclusions. To assess the psychological status of patients with first diagnosed infiltrative pulmonary tuberculosis, it is advisable to use the STAI and the BDI. Patients with first diagnosed infiltrative pulmonary tuberculosis in 100 % of cases have psychological status disorders with a predominance of moderate state anxiety and the absence of depressive disorders in only half of them. More expressed violations of the psychological status (anxiety, depression) identifies patients who are married and have a steady job. In patients with first diagnosed infiltrative pulmonary tuberculosis, an increase in the severity of anxiety and depression is associated with more expressed bacterial excretion, decrease in body weight, greater frequency of destruction of lung tissue, prevalence of the tuberculosis process by more than 2 lung segments, decrease in the effectiveness of standard therapy and prolongation intensive phase of treatment.

Multidrug-resistant tuberculosis in the United States, 2011-2016: patient characteristics and risk factors

OBJECTIVE: To determine risk factors for multidrug-resistant tuberculosis (MDR-TB) and describe MDR-TB according to three characteristics: previous TB disease, recent transmission of MDR-TB, and reactivation of latent MDR-TB infection.SETTING and DESIGN: We used 2011-2016 surveillance data from the US National Tuberculosis Surveillance System and National Tuberculosis Genotyping Service and used logistic regression models to estimate risk factors associated with MDR-TB.RESULTS: A total of 615/45 209 (1.4%) cases were confirmed as MDR-TB; 111/615 (18%) reported previous TB disease; 41/615 (6.7%) were attributed to recent MDR-TB transmission; and 449/615 (73%) to reactivation. Only 12/41 (29%) patients with TB attributed to recent transmission were known to be contacts of someone with MDR-TB. For non-US-born patients, the adjusted odds ratios of having MDR-TB were 32.6 (95%CI 14.6-72.6) among those who were known to be contacts of someone with MDR-TB and 6.5 (95%CI 5.1-8.3) among those who had had previous TB disease.CONCLUSION: The majority of MDR-TB cases in the United States were associated with previous TB disease or reactivation of latent MDR-TB infection; only a small proportion of MDR-TB cases were associated with recent transmission.

A Review of Clinical Pharmacokinetic and Pharmacodynamic Relationships and Clinical Implications for Drugs Used to Treat Multi-drug Resistant Tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is becoming a global health crisis. The World Health Organization has released new guidelines for the use of tuberculosis-active drugs for the treatment of patients with MDR-TB. Despite documented activity against tuberculosis isolates, doses and exposure targets are yet to be optimized. Our objective was therefore to review the clinical pharmacokinetic and pharmacodynamic literature pertaining to drugs recommended to treat MDR-TB and to identify target areas for future research. To date, published research is limited but studies were identified that evaluated the pharmacokinetics and pharmacodynamics of these drugs. Exposure targets were assessed and summarized for each drug. Exposure-based targets (e.g., area under the concentration curve/minimum inhibitory concentration) appear to be most commonly associated with predicting drug efficacy. Dose variation studies based on these targets were largely inconclusive. Future research should focus on determining the risks and benefits of dose optimization to meet exposure targets and improve patient outcomes. The role of therapeutic drug monitoring also remains yet to be confirmed, both from a clinical perspective as well as a resource allocation perspective in regions where MDR-TB is active.

The technology behind TB DEPOT: a novel public analytics platform integrating tuberculosis clinical, genomic, and radiological data for visual and statistical exploration

OBJECTIVE

Clinical research informatics tools are necessary to support comprehensive studies of infectious diseases. The National Institute of Allergy and Infectious Diseases (NIAID) developed the publicly accessible Tuberculosis Data Exploration Portal (TB DEPOT) to address the complex etiology of tuberculosis (TB).

MATERIALS AND METHODS

TB DEPOT displays deidentified patient case data and facilitates analyses across a wide range of clinical, socioeconomic, genomic, and radiological factors. The solution is built using Amazon Web Services cloud-based infrastructure, .NET Core, Angular, Highcharts, R, PLINK, and other custom-developed services. Structured patient data, pathogen genomic variants, and medical images are integrated into the solution to allow seamless filtering across data domains.

RESULTS

Researchers can use TB DEPOT to query TB patient cases, create and save patient cohorts, and execute comparative statistical analyses on demand. The tool supports user-driven data exploration and fulfills the National Institute of Health's Findable, Accessible, Interoperable, and Reusable (FAIR) principles.

DISCUSSION

TB DEPOT is the first tool of its kind in the field of TB research to integrate multidimensional data from TB patient cases. Its scalable and flexible architectural design has accommodated growth in the data, organizations, types of data, feature requests, and usage. Use of client-side technologies over server-side technologies and prioritizing maintenance have been important lessons learned. Future directions are dynamically prioritized and key functionality is shared through an application programming interface.

CONCLUSION

This paper describes the platform development methodology, resulting functionality, benefits, and technical considerations of a clinical research informatics application to support increased understanding of TB.

Novel stilbene scaffolds efficiently target Mycobacterium tuberculosis nucleoid-associated protein, HU

Novel scaffolds of stilbene were identified as inhibitors of Mycobacterium tuberculosis by targeting the nucleoid-associated protein, HU, using molecular docking.

Of tuberculosis and non-tuberculous mycobacterial infections - a comparative analysis of epidemiology, diagnosis and treatment

Pulmonary diseases due to mycobacteria cause significant morbidity and mortality to human health. In addition to tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), recent epidemiological studies have shown the emergence of non-tuberculous mycobacteria (NTM) species in causing lung diseases in humans. Although more than 170 NTM species are present in various environmental niches, only a handful, primarily Mycobacterium avium complex and M. abscessus, have been implicated in pulmonary disease. While TB is transmitted through inhalation of aerosol droplets containing Mtb, generated by patients with symptomatic disease, NTM disease is mostly disseminated through aerosols originated from the environment. However, following inhalation, both Mtb and NTM are phagocytosed by alveolar macrophages in the lungs. Subsequently, various immune cells are recruited from the circulation to the site of infection, which leads to granuloma formation. Although the pathophysiology of TB and NTM diseases share several fundamental cellular and molecular events, the host-susceptibility to Mtb and NTM infections are different. Striking differences also exist in the disease presentation between TB and NTM cases. While NTM disease is primarily associated with bronchiectasis, this condition is rarely a predisposing factor for TB. Similarly, in Human Immunodeficiency Virus (HIV)-infected individuals, NTM disease presents as disseminated, extrapulmonary form rather than as a miliary, pulmonary disease, which is seen in Mtb infection. The diagnostic modalities for TB, including molecular diagnosis and drug-susceptibility testing (DST), are more advanced and possess a higher rate of sensitivity and specificity, compared to the tools available for NTM infections. In general, drug-sensitive TB is effectively treated with a standard multi-drug regimen containing well-defined first- and second-line antibiotics. However, the treatment of drug-resistant TB requires the additional, newer class of antibiotics in combination with or without the first and second-line drugs. In contrast, the NTM species display significant heterogeneity in their susceptibility to standard anti-TB drugs. Thus, the treatment for NTM diseases usually involves the use of macrolides and injectable aminoglycosides. Although well-established international guidelines are available, treatment of NTM disease is mostly empirical and not entirely successful. In general, the treatment duration is much longer for NTM diseases, compared to TB, and resection surgery of affected organ(s) is part of treatment for patients with NTM diseases that do not respond to the antibiotics treatment. Here, we discuss the epidemiology, diagnosis, and treatment modalities available for TB and NTM diseases of humans.

Assessing whether isoniazid is essential during the first 14 days of tuberculosis therapy: a phase 2a, open-label, randomised controlled trial

Background

Clinical studies suggest that isoniazid contributes rapid bacterial killing during the initial two days of tuberculosis treatment but that isoniazid's activity declines significantly after day three. We conducted a 14-day phase IIa open label, randomized trial to assess the essentiality of isoniazid in standard tuberculosis therapy.

Methods

A total of 69 adults with newly diagnosed sputum-positive tuberculosis from the South African Western Cape region were enrolled and randomized to a four-arm parallel assignment model. Participants were followed for 14 days as inpatients at either the University of Cape Town Lung Institute or at the TASK Applied Science clinical research organization. All arms received standard daily rifampicin, ethambutol, and pyrazinamide but differed as follows: isoniazid only on days one and two (n=17), isoniazid on days one and two then moxifloxacin on days three through 14 (n=16), no isoniazid (n=18), and a control group that received isoniazid for all 14 days (standard therapy, n=18). The primary endpoint was the rate of colony forming unit (CFU) decline during the first 14 days of treatment.

Results

For 62 participants analyzed, the initial 14-day mean daily fall in log₁₀ CFU (95% CI) was 0·14 (0·11, 0·18) for participants receiving isoniazid for two days only; 0·13 (0·09, 0·17) for participants receiving isoniazid for two days followed by moxifloxacin; 0·12 (0·08, 0·15) for those not receiving isoniazid; and 0·13 (0·09, 0·16) for the standard therapy group.

Conclusions

The 14 day EBA for the combination rifampicin, ethambutol, and pyrazinamide was not significantly changed by the addition of isoniazid for the first two days or for the first 14 days of treatment. In a post hoc analysis, significantly higher day-two EBAs were observed for all groups among participants with higher baseline sputum CFUs. Our finding that INH does not contribute to EBA suggests that INH could be replaced with another drug during standard treatment to improve efficacy and decrease rates of resistance to first-line drugs. (Funded by the NIH AIDS Clinical Trial Groups and NIH; A5307 ClinicalTrials.gov number, NCT01589497).

Evaluation of heterologous prime-boost vaccination strategies using chimpanzee adenovirus and modified vaccinia virus for TB subunit vaccination in rhesus macaques

Tuberculosis (TB) still is the principal cause of death from infectious disease and improved vaccination strategies are required to reduce the disease burden and break TB transmission. Here, we investigated different routes of administration of vectored subunit vaccines based on chimpanzee-derived adenovirus serotype-3 (ChAd3) for homologous prime-boosting and modified vaccinia virus Ankara (MVA) for heterologous boosting with both vaccine vectors expressing the same antigens from Mycobacterium tuberculosis (Ag85B, ESAT6, Rv2626, Rv1733, RpfD). Prime-boost strategies were evaluated for immunogenicity and protective efficacy in highly susceptible rhesus macaques. A fully parenteral administration regimen was compared to exclusive respiratory mucosal administration, while parenteral ChAd3-5Ag prime-boosting and mucosal MVA-5Ag boosting were applied as a push-and-pull strategy from the periphery to the lung. Immune analyses corroborated compartmentalized responses induced by parenteral versus mucosal vaccination. Despite eliciting TB-specific immune responses, none of the investigational regimes conferred a protective effect by standard readouts of TB compared to non-vaccinated controls, while lack of protection by BCG underpinned the stringency of this non-human primate test modality. Yet, TB manifestation after full parenteral vaccination was significantly less compared to exclusive mucosal vaccination.

Manuka honey chelates iron and impacts iron regulation in key bacterial pathogens

AIM

The aim of this study was to test the hypothesis that Manuka honey (MH) chelates iron and promotes an iron-limiting environment, which contributes to its antimicrobial activity.

METHODS AND RESULTS

Employing a ferrozine-based assay, we observed that MH is an iron chelator that depletes iron from solution. Siderophores are small molecules that bind ferric iron (III) with high affinity and their levels are upregulated by bacteria under iron-limiting conditions. We demonstrated by quantitating siderophore production that Escherichia coli and Pseudomonas aeruginosa treated with MH sub-minimum inhibitory concentrations (sub-MIC) experience an iron-limiting environment and increase siderophore production. In addition, supplementation with ferrous iron (II) significantly increased growth of E. coli, Staphylococcus aureus and P. aeruginosa cultured at their MH MIC above that observed in nonsupplemented controls. By contrast, supplementation with ferric iron (III) significantly increased growth for only E. coli and P. aeruginosa, above their nonsupplemented controls.

CONCLUSIONS

Manuka honey chelates iron, thereby generating an iron-limiting environment for E. coli and P. aeruginosa, and to a lesser extent S. aureus, which contributes to its antimicrobial properties.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our work demonstrates that MH-induced iron chelation is an antimicrobial mechanism that differentially impacts the bacterial species tested here. Iron chelation affects multiple diverse physiological processes in bacteria and would contribute to the lack of bacterial resistance to MH. Iron metabolism is tightly regulated; bacteria require this essential nutrient for survival, but in excess it is toxic. Additional exploration of MH's iron chelation mechanism will facilitate its future use in mainstream medicine.

Epidemiology of drug-resistant tuberculosis in Chongqing, China: A retrospective observational study from 2010 to 2017

China is one of the top 30 countries with high multidrug-resistant tuberculosis (MDR-TB) and rifampin-resistant tuberculosis (RR-TB) burden. Chongqing is a southwest city of China with a large rural population. A retrospective observational study has been performed based on routine tuberculosis (TB) surveillance data in Chongqing from 2010 to 2017. The MDR/RR-TB notification rate increased from 0.03 cases per 100,000 population in 2010 to 2.1 cases per 100,000 population in 2017. The extensively drug-resistant TB (XDR-TB) notification rate has increased to 0.09 cases per 100,000 population in 2017. There was a decreasing detection gap between the number of notified MDR/RR-TB cases and the estimate number of MDR/RR-TB cases in new TB cases. The treatment success rate of MDR/RR-TB was 59% (95% confidence interval [CI], 53%-65%) in this period. Despite the progress achieved, the prevalence of MDR/RR-TB was still high facing challenges including detection gaps in new TB cases, the regional disparity, and the high risk for MDR/RR-TB in elderly people and farmers. Sustained government financing and policy support should be guaranteed in the future.

Assessment of multidrug-resistant tuberculosis (MDR-TB) treatment outcomes in Sudan; findings and implications

Background: Multidrug-resistant tuberculosis (MDR-TB) has a socioeconomic impact and threatens global public health. We assessed treatment outcomes of MDR-TB and predictors of poor treatment outcomes in Sudan given current high prevalence rates.Methods: Combined retrospective and prospective cohort study at Abu-Anga hospital (TB specialized hospital in Sudan). All patients with MDR-TB between 2013 and 2017 were targeted.Results: A total of 156 patients were recruited as having good records, 117 (75%) were male, and 152 (97.4%) had pulmonary TB. Patients were followed for a median of 18 months and a total of 2108 person-months. The overall success rate was 63.5% and the mortality rate was 14.1%. Rural residency (P < 0.05) and relapsing on previous treatments (P < 0.05) were determinants of time to poor MDR-TB treatment outcomes.Conclusion: Overall, more attention needs to be given to special MDR-TB groups that are highly susceptible to poor outcomes, i.e. rural patients. As a result, it is highly recommended to maintain total coverage of medicines for all MDR-TB patients for the entire period of treatment in Sudan. It is also recommended to instigate more treatment centers in rural areas in Sudan together with programs to enhance adherence to treatments including patient counseling to improve future outcomes.

Use of whole genome sequencing in surveillance of drug resistant tuberculosis

INTRODUCTION

The threat of resistance to anti-tuberculosis drugs is of global concern. Current efforts to monitor resistance rely on phenotypic testing where cultured bacteria are exposed to critical concentrations of the drugs. Capacity for such testing is low in TB endemic countries. Drug resistance is caused by mutations in the Mycobacterium tuberculosis genome and whole genome sequencing to detect these mutations offers an alternative means of assessing resistance. Areas covered: The challenges of assessing TB drug resistance are discussed. Progress in elucidating the M. tuberculosis resistome and evidence of the accuracy of next generation sequencing for detecting resistance is reviewed. Expert Commentary: There are considerable advantages to using next generation sequencing for TB drug resistance surveillance. Accuracy is high for detecting resistance to the major first-line drugs but is currently lower for the second-line drugs due to our incomplete knowledge regarding resistance causing mutations. With the advances in sequencing technology and the opportunity to replace phenotypic drug susceptibility testing with safer and more cost effective methods it would appear that the question is when to implement. Current bottlenecks are sample extraction to allow whole genome sequencing directly from sputum and the lack of bioinformatics expertise in some TB endemic countries.