Clinical management of adults and children with multidrug-resistant and extensively drug-resistant tuberculosis

[Pre-extensively and extensively drug-resistant tuberculosis, in Libreville, Gabon]

INTRODUCTION

Very few studies have been devoted to extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis (TB) in Gabon.

AIM

The aim of the present study is to present the epidemiology of pre-XDR and XDR TB and the evolution over time of patients with multidrug-resistant TB.

METHODS

This retrospective study covered the activities from 2019 to 2022 of the Nkembo anti-tuberculosis center.

RESULTS

Fifteen patients were eligible, including 11 (73.3%) pre-XDR patients and 4 (26.7%) XDR-TB patients. Three (20.0%) patients had HIV/TB co-infection. The sample consisted of 7 men (46.7%) and 8 women (53.3%), a sex ratio (M/F) of 0.87. The average age was 35.6 years, and the median 34 years, with extremes of 23 and 60 years. Eight patients (53.3%) represented new cases of pre-XDR or XDR-TB tuberculosis. The majority (60%; n=9) came from deprived neighborhoods with widespread promiscuity. The therapeutic success rate among pre-XDR patients was 4 (36.4%) versus 2 (50.0%) among XDR-TB patients. Reported mortality occurred 5 (33.3%) patients during treatment, including 3 pre-XDR and 2 XDR-TB patients. In all cases, they died before the end of the first trimester of follow-up.

CONCLUSION

The high frequency of primary pre-extensively drug-resistant tuberculosis underscores the pervasiveness of resistance to anti-tuberculosis drugs and underlines a pressing need for detection of contact cases and early treatment.

Mtb-Selective 5-Aminomethyl Oxazolidinone Prodrugs: Robust Potency and Potential Liabilities

Linezolid is a drug with proven human antitubercular activity whose use is limited to highly drug-resistant patients because of its toxicity. This toxicity is related to its mechanism of action─linezolid inhibits protein synthesis in both bacteria and eukaryotic mitochondria. A highly selective and potent series of oxazolidinones, bearing a 5-aminomethyl moiety (in place of the typical 5-acetamidomethyl moiety of linezolid), was identified. Linezolid-resistant mutants were cross-resistant to these molecules but not vice versa. Resistance to the 5-aminomethyl molecules mapped to an N-acetyl transferase (Rv0133) and these mutants remained fully linezolid susceptible. Purified Rv0133 was shown to catalyze the transformation of the 5-aminomethyl oxazolidinones to their corresponding N-acetylated metabolites, and this transformation was also observed in live cells of Mycobacterium tuberculosis. Mammalian mitochondria, which lack an appropriate N-acetyltransferase to activate these prodrugs, were not susceptible to inhibition with the 5-aminomethyl analogues. Several compounds that were more potent than linezolid were taken into C3HeB/FeJ mice and were shown to be highly efficacious, and one of these (9) was additionally taken into marmosets and found to be highly active. Penetration of these 5-aminomethyl oxazolidinone prodrugs into caseum was excellent. Unfortunately, these compounds were rapidly converted into the corresponding 5-alcohols by mammalian metabolism which retained antimycobacterial activity but resulted in substantial mitotoxicity.

Trends and risk factors for drug-resistant tuberculosis among children in Sichuan, China: A 10-year retrospective analysis, 2013-2022

To investigate the status of the drug-resistant tuberculosis (DR-TB) among children in Sichuan, and to find out the risk factors and high-risk population related to drug resistance among children. The clinical data of tuberculosis patients ≤14 years old with culture-confirmed tuberculosis hospitalized in Chengdu Public Health Clinical Center from January 2013 through December 2022 were collected. Clinical data such as gender, age, ethnicity, history of anti-TB treatment, history of exposure to tuberculosis, nutritional status, and specific drug resistance of the children were collected and recorded. The drug resistance of children in different age groups (0-4 years old, 5-9 years old, 10-14 years old) and different periods (2013-2017 and 2018-2022) were grouped and compared. Logistic regression analysis was to analyze analysis of risk factors of drug resistance in children. A total of 438 children with culture-confirmed tuberculosis were screened. Among them, 26.19% (11/42) were 0 to 4 years old, 33.33% (22/66) were 5 to 9 years old, and 36.67% (121/330) were 10 to 14 years old among the resistant children. There was no statistically significant difference in the resistance rate among the 3 groups (P = .385). The proportions of DR-TB, monoresistant tuberculosis, polydrug-resistant tuberculosis were decreased during 2019 to 2022 compared with 2013 to 2017 (P < .0001). The resistance rates of drug resistant, monoresistant, polydrug-resistant, isoniazid-resistant, and rifampicin resistant during 2018 to 2022 were decreased compared with those from 2013 to 2017 (P < .05), but the multi-drug resistance rate was not decreased (P = .131, without statistical difference). The results of logistic regression analysis showed that male gender OR = 1.566 (95% CI 1.035-2.369), a history of antituberculosis therapy OR = 4.049 (95% CI 1.442-11.367), and pulmonary and extrapulmonary tuberculosis OR = 7.335 (95% CI 1.401-38.392) were risk factors for the development of drug resistance; but fever OR = 0.581 (95% CI 0.355-0.950) was Protective factor. The total drug resistance rate of children in Sichuan showed a downward trend, but the rate of multi-drug-resistant tuberculosis was still at a high level, and the form of drug resistance was still severe. Absence of fever, male, retreatment, and pulmonary concurrent with extrapulmonary tuberculosis are risk factors for DR-TB in children.

Multi-Drug Resistance Tuberculosis (MDR-TB) Challenges in India: A Review

Tuberculosis (TB) is an increasing public health concern in India. The development of resistance to two of the most effective medications, rifampicin, and isoniazid, is the largest worldwide challenge in the management of TB. An epidemiological indicator used to evaluate the effectiveness of the TB management program is the initial medication resistance level. Our search for published papers in English using Medical Subject Heading phrases was conducted through PubMed, Google Scholar, and Scopus. We also looked through several official sources to learn the most recent information on multi-drug resistance in India. Multi-drug resistance tuberculosis is a significant risk to human health globally. Stigmatization or discrimination of those who have TB or who are impacted by it can make the disease more difficult to manage medically and socially, and it is ultimately responsible for missed opportunities for diagnosis and treatment, interruptions of care, and unsuccessful outcomes. Eliminating TB is complicated by stigma.

Development of a HPLC Method for Analysis of a Combination of Clofazimine, Isoniazid, Pyrazinamide, and Rifampicin Incorporated into a Dermal Self-Double-Emulsifying Drug Delivery System

We describe the development and validation of a new high performance liquid chromatography (HPLC) method for analysis of a combination of the first-line anti-tubercular drugs isoniazid, pyrazinamide, and rifampicin together with clofazimine. This is a unique challenge since clofazimine and rifampicin are relatively highly lipophilic drugs, whereas isoniazid and pyrazinamide are considerably more hydrophilic. Thus, clear separation of peaks and quantification of four individual drugs can present difficulties during the development of an analytical method. Detection was established at two wavelengths-254 nm for isoniazid and pyrazinamide and 320 nm for clofazimine and rifampicin. Gradient elution was employed using 0.1% aqueous formic acid (A) and acetonitrile (B); clear separation of the four drugs was achieved within 10 min. A linear relationship was indicated by a correlation coefficient (r2) of 0.9999 for each anti-tubercular drug, respectively. The limit of detection (LOD) for the individual drugs was 0.70 µg/mL (isoniazid), 0.30 µg/mL (pyrazinamide), 0.20 µg/mL (rifampicin) and 0.20 µg/mL (clofazimine). Precision experiments rendered a mean recovery percentage of 101.25% (isoniazid), 98.70% (pyrazinamide), 99.68% (rifampicin) and 97.14% (clofazimine). This HPLC method was validated and is reliable, repeatable, and accurate for the purpose of conducting simultaneous HPLC analyses of the four anti-tubercular drugs.

Missed phenotypic drug resistance in pediatric tuberculosis: A cause of concern in a resource-limited setting

BACKGROUND

Multi-drug resistance (MDR) in pediatric tuberculosis (TB) is a growing global threat. Unavailability of conventional or molecular drug susceptibility test (DST) in resource-limited settings often impede the determination of the extent of first line anti-tubercular drugs deployed in national programs.

MATERIALS AND METHOD

Pulmonary and extra pulmonary specimens were collected from clinically suspected pediatric TB cases, who were microbiologically confirmed. Resistance to first-line anti-TB was detected by 1% proportion method. KatG315 and inhA-15 genes were amplified by PCR and detection of mutations were done by sequencing. Genotypic resistance for rifampicin was detected by Xpert MTB/RIF assay (Cepheid Inc., Sunnyvale, California).

RESULTS

Fifty-one cases of pediatric tuberculosis were confirmed microbiologically. Resistance to isoniazid, streptomycin, rifampicin and ethambutol were 5 (14%), 4 (11%), 2 (5.5%) and 2 (5.5%) respectively by 1% proportion method. Genotypic Rifampicin and isoniazid resistance was found in 2 (5.5%) and 7 (14%) samples respectively.

CONCLUSION

Existing genotypic methods, detect targeted mutations conferring rifampicin resistance, however isoniazid (INH) resistance often go undetected. Since the resistance to pivotal anti-TB drugs are often encoded by multiple genes which may not be targeted by widely available molecular tests, discrepancies in molecular and culture-based DST reports should be interpreted with caution.

Prevalence of long-term physical sequelae among patients treated with multi-drug and extensively drug-resistant tuberculosis: a systematic review and meta-analysis

BACKGROUND

Physical sequelae related to multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are emerging and under-recognised global challenges. This systematic review and meta-analysis aimed to quantify the prevalence and the types of long-term physical sequelae associated with patients treated for MDR- and XDR-TB.

METHODS

We systematically searched CINAHL (EBSCO), MEDLINE (via Ovid), Embase, Scopus, and Web of Science from inception through to July 1, 2022, and the last search was updated to January 23, 2023. We included studies reporting physical sequelae associated with all forms of drug-resistant TB, including rifampicin-resistant TB (RR-TB), MDR-TB, Pre-XDR-TB, and XDR-TB. The primary outcome of interest was long-term physical sequelae. Meta-analysis was conducted using a random-effect model to estimate the pooled proportion of physical sequelae. The sources of heterogeneity were explored through meta-regression using study characteristics as covariates. The research protocol was registered in PROSPERO (CRD42021250909).

FINDINGS

From 3047 unique publications identified, 66 studies consisting of 37,380 patients conducted in 30 different countries were included in the meta-analysis. The overall pooled estimate was 44.4% (95% Confidence Interval (CI): 36.7-52.1) for respiratory sequelae, 26.7% (95% CI: 23.85-29.7) for hearing sequelae, 10.1% (95% CI: 7.0-13.2) for musculoskeletal sequelae, 8.4% (95% CI: 6.5-10.3) for neurological sequelae, 8.1% (95% CI: 6.3-10.0) for renal sequelae, 7.3% (95% CI: 5.1-9.4) for hepatic sequelae, and 4.5% (95% CI: 2.7-6.3) for visual sequelae. There was substantial heterogeneity in the estimates. The stratified analysis showed that the pooled prevalence of hearing sequelae was 26.6% (95% CI: 12.3-40.9), neurological sequelae was 31.5% (95% CI: 5.5-57.5), and musculoskeletal sequelae were 21.5% (95% CI: 9.9-33.1) for patients with XDR-TB, which were higher than the pooled prevalence of sequelae among patients with MDR-TB. Respiratory sequelae were the highest in low-income countries (59.3%) and after completion of MDR-TB treatment (57.7%).

INTERPRETATION

This systematic review found that long-term physical sequelae such as respiratory, hearing, musculoskeletal, neurological, renal, hepatic, and visual sequelae were common among survivors of MDR- and XDR-TB. There was a significant difference in the prevalence of sequelae between patients with MDR- and XDR-TB. Post-MDR- and XDR-TB treatment surveillance for adverse outcomes needs to be incorporated into the current programmatic management of MDR-TB to enable early detection and prevention of post-treatment sequelae.

FUNDING

Australian National Health and Medical Research Council, through an Emerging Leadership Investigator grant, and the Curtin University Higher Degree Research scholarship.

Multidrug-Resistant TB (MDR-TB) and Extensively Drug-Resistant TB (XDR-TB) Among Children: Where We Stand Now

Drug-resistant tuberculosis (DR-TB) has continued to be a global health cataclysm. It is an arduous condition to tackle but is curable with the proper choice of drug and adherence to the drug therapy. WHO has introduced newer drugs with all-oral shorter regimens, but the COVID-19 pandemic has disrupted the achievements and raised the severity. The COVID-19 controlling mechanism is based on social distancing, using face masks, personal protective equipment, medical glove, head shoe cover, face shield, goggles, hand hygiene, and many more. Around the globe, national and international health authorities impose lockdown and movement control orders to ensure social distancing and prevent transmission of COVID-19 infection. Therefore, WHO proposed a TB control program impaired during a pandemic. Children, the most vulnerable group, suffer more from the drug-resistant form and act as the storehouse of future fatal cases. It has dire effects on physical health and hampers their mental health and academic career. Treatment of drug-resistant cases has more success stories in children than adults, but enrollment for treatment has been persistently low in this age group. Despite that, drug-resistant childhood tuberculosis has been neglected, and proper surveillance has not yet been achieved. Insufficient reporting, lack of appropriate screening tools for children, less accessibility to the treatment facility, inadequate awareness, and reduced funding for TB have worsened the situation. All these have resulted in jeopardizing our dream to terminate this deadly condition. So, it is high time to focus on this issue to achieve our Sustainable Development Goals (SDGs), the goal of ending TB by 2030, as planned by WHO. This review explores childhood TB's current position and areas to improve. This review utilized electronic-based data searched through PubMed, Google Scholar, Google Search Engine, Science Direct, and Embase.

Antibiotic resistance acquisition versus primary transmission in the presentation of extensively drug-resistant tuberculosis

Mycobacterium tuberculosis is the leading cause of mortality worldwide due to a single bacterial pathogen. Of concern is the negative impact that the COVID-19 pandemic has had on the control of tuberculosis (TB) including drug-resistant forms of the disease. Antimicrobial resistance increases the likelihood of worsened outcomes in TB patients including treatment failure and death. Multidrug-resistant (MDR) strains, resistant to first-line drugs isoniazid and rifampin, and extensively drug-resistant (XDR) strains with further resistance to second-line drugs (SLD), threaten control programs designed to lower TB incidence and end the disease as a public health challenge by 2030, in accordance with UN Sustainable Development Goals. Tackling TB requires an understanding of the pathways through which drug resistance emerges. Here, the roles of acquired resistance mutation, and primary transmission, are examined with regard to XDR-TB. It is apparent that XDR-TB can emerge from MDR-TB through a small number of additional resistance mutations that occur in patients undergoing drug treatment. Rapid detection of resistance, to first-line drugs and SLD, at the initiation of and during treatment, and prompt adjustment of regimens are required to ensure treatment success in these patients. Primary transmission is predicted to make an increasing contribution to the XDR-TB caseload in the future. Much work is required to improve the implementation of the World Health Organization-recommended infection control practices and block onward transmission of XDR-TB patients to contacts including health-care workers. Finally, limiting background resistance to fluoroquinolones in pre-XDR strains of M. tuberculosis will necessitate better antimicrobial stewardship in the broader use of this drug class.

Patient-centered approach to the management of drug-resistant tuberculosis in France: How far off the mark are we?

Drug-resistant tuberculosis (DR-TB) is a major public health concern worldwide. The prolonged isolation required is a source of challenges for both healthcare workers and patients, especially in high-income countries where DR-TB patients are frequently migrants with vulnerabilities. However, data on the needs of these vulnerable patients are scarce. Our objective was to identify and quantify conflict or inappropriate care situations experienced by both DR-TB patients and healthcare workers. This 10-year retrospective observational study (01/2008 to 10/2018) was conducted in a referral center for resistant tuberculosis management in Paris, France. Sixty-five DR-TB patients were hospitalized during the study period. Their demographic, clinical and social characteristics and any conflict or inappropriate care situations they experienced with healthcare workers while hospitalized were analyzed. Conflict or inappropriate care situations with healthcare workers were reported for 24 patients during their stay (36.9%). Eleven patients (16.9%) had difficulty adhering to respiratory isolation rules, 15 (23.1%) were discharged against medical advice, 9 (13.8%) were excluded from hospital for disciplinary reasons, verbal or physical violence was reported for 7 patients (10.8%), and 4 arrests (6.2%) were made by the police. Conflict situations were reported more often when there was a language barrier (70.8%, p<0.0001). More than one-third of patients with DR-TB in this referral center experienced at least one inappropriate care situation with healthcare workers. This study illustrates the urgent need to promote a patient-centered approach and to respond to the challenges of its practical implementation.

Drug-Resistant Tuberculosis Among Children: A Systematic Review and Meta-Analysis

Background: Drug-resistant tuberculosis (DR-TB), especially multidrug-resistant tuberculosis (MDR-TB) is a public health threat. Little is known about estimates of different profiles and rates of DR-TB among children globally. Methods: We did a systematic review and meta-analysis of observational studies reporting DR-TB among children by searching Embase, PubMed, and Scopus databases from January 1, 2000 to October 1, 2020. Publications reporting more than 60 children with bacteriological confirmed tuberculosis and phenotypical drug susceptibility testing (DST) results were included. Pooled proportions of MDR-TB and sub-analysis by age subgroups, regions, economical levels were performed. Results: We identified 4,063 studies, of which 37 were included. Of 23,652 pediatric TB patients, the proportions of DR-TB, MDR-TB, mono-resistant TB, polydrug resistant TB, extensively drug-resistant TB were 13.59% (1,964/14,453), 3.72% (881/23,652), 6.07% (529/8,719), 1.61% (119/7,361), 0.44% (30/6,763), respectively. The pooled proportion of MDR-TB among 23,652 children of 37 studies was 3.7% (95% CI, 3.5-4.0%). Rate of MDR-TB was much lower in high-income countries (1.8%) than that in lower-middle-income countries (6.3%) and upper-middle-income countries (7.3%). More specifically, the rates of MDR-TB were 1.7% in USA, 1.7% in UK, 2.9% in India, 6.0% in South Africa, 9.8% in China, respectively. Conclusions: The burden of DR-TB remains high in children, and there are potential associations between rates of pediatric MDR-TB and national economical levels. More interventions on child TB cases in low-income countries may be urgently needed in future.

A systematic review of pharmacoeconomic evaluations on oral diarylquinoline-based treatment for drug-resistant tuberculosis: from high to low burden countries

Introduction: There is a rising global interest in the pharmacoeconomic evaluations of bedaquiline (BDQ), a novel oral diarylquinoline, for treatment of drug-resistant tuberculosis (DR-TB).Areas covered: This article systematically reviewed publications retrieved from Medline, American Psychological Association-Psychology information, Web of Science, Embase, Scopus, Science direct, Center for Reviews and Dissemination, and CINAHL Complete during 2010-2020 on pharmacoeconomic studies on BDQ for DR-TB treatment. Ten Markov model-based cost-effectiveness analyses identified were conducted in high (n = 4), intermediate (n = 2), and low (n = 4) TB burden countries.Expert opinion: The paucity of model-based health economic analyses on BDQ-containing regimens for DR-TB indicated that further pharmacoeconomic research of BDQ-based regimens, on the aspects of duration of BDQ treatment, types of DR-TB indicated, and settings of regions and health-systems, is highly warranted to inform global cost-effective use of BDQ-based regimens for DR-TB treatment.

Evaluating bedaquiline as a treatment option for multidrug-resistant tuberculosis

Introduction: Despite efforts to the contrary, tuberculosis remains one of the leading causes of death in the world. The appearance of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis has increased the need for new therapeutic options against these strains.Areas covered: This review covers the in vitro susceptibility, pharmacokinetics, and pharmacodynamics of bedaquiline, a new drug shown to be active against M. tuberculosis-resistant strains. The authors further review clinical data concerning its use against MDR and XDR strains, discussing recent clinical guidelines from different international societies.Expert opinion: Available data demonstrate the usefulness of bedaquiline against resistant M. tuberculosis. Despite the difficulty in analyzing multidrug therapies, the use of bedaquiline in MDR and XDR tuberculosis increases success rates, allowing shortened treatments and lower drug use than previously recommended regimens. Moreover, the fact that MDR and XDR strains are common in many places creates a need to include this drug in the currently available protocols. It is essential to overcome the substantial barriers that some countries encounter in obtaining bedaquiline, as doing so will make therapeutic regimens including this drug available for all patients.

Drug-Resistant Tuberculosis: A Glance at Progress and Global Challenges

Multidrug-resistant Mycobacterium tuberculosis remains a major public health threat; its management poses a significant economic burden. Treatment requires a programmatic approach with access to laboratory services, second-line medications, and adequate clinical resources. In recent years, we have seen rapid developments in diagnostic techniques with whole genome sequencing-based drug susceptibility prediction now in reach, an array of new drugs that transform treatment regimens to purely oral formulations, and a steady stream of multinational trials that inform us about most efficient combinations. Our hope is that the current momentum keeps the ambitious goal to end tuberculosis in 2030 in reach.

Pyrazinamide Resistance and Mutation Patterns Among Multidrug-Resistant Mycobacterium tuberculosis from Henan Province

PURPOSE

This study was designed to identify the phenotypic and genotypic characteristics of pyrazinamide (PZA) resistance among multidrug-resistant Mycobacterium tuberculosis (MDR-TB) from Henan and to evaluate the efficacy of pncA, rpsA, and panD mutations in predicting PZA resistance.

MATERIALS AND METHODS

A total of 152 MDR strains were included in this study. The Bactec MGIT system was used to determine PZA susceptibility for all strains. The pncA, rpsA, and panD genes were sequenced to identify any mutations, and the sequences were then aligned with the sequence of standard strain H37Rv. Moreover, the correlations between PZA-resistant phenotypes and treatment outcomes were analysed.

RESULTS

Of the152 strains, 105 had a PZA-resistant phenotype, and 102 harboured the pncA mutation. The PZA resistance rate was higher in the strains with resistance to all four first-line drugs and those that were pre-extensively drug-resistant (pre-XDR) and extensively drug-resistant (XDR). A total of 100 different pncA mutation patterns were identified, including 80 point mutations and 20 insertions/deletions, and 32 new pncA mutation patterns were detected. In this study, 13 strains had multiple mutations. Of the11 PZA-resistant strains without pncA mutations, two harboured the rpsA mutation, and one harboured the panD mutation. With PZA susceptibility results as the reference, single-gene pncA sequencing had sensitivity of 89.52% and specificity of 89.36%. With the combination of rpsA and panD, the sensitivity increased to 92.38%, and the specificity remained the same. No significant differences were observed in the sputum smear/culture conversion rate between PZA-resistant patients and PZA-sensitive patients. However, PZA resistance was related to the time to sputum smear/culture conversion (P = 0.018).

CONCLUSION

The combination of pncA, rpsA, and panD was beneficial for the timely diagnosis of PZA resistance and could provide a laboratory basis for customizing treatment regimens for MDR-TB patients.

Reduced susceptibility of Mycobacterium tuberculosis to bedaquiline during antituberculosis treatment and its correlation with clinical outcomes in China

BACKGROUND

We aimed to assess the proportion of multidrug-resistant tuberculosis (MDR-TB) cases with initial bedaquiline (BDQ) resistance, monitored dynamics of BDQ susceptibility of Mycobacterium tuberculosis (MTB) isolates during therapy, and correlated susceptibility with MDR-TB patient clinical outcomes in China.

METHODS

A retrospective cohort study of MDR-TB patients was conducted, with positive cultures collected from cases at 13 sites. Patients with nontuberculous mycobacterial infection during anti-TB therapy were excluded. BDQ minimal inhibitory concentrations (MICs) were determined using a 7H9 Middlebrook broth-based microdilution method. Mutations conferring BDQ resistance were detected via Sanger sequencing.

RESULTS

277 patients receiving BDQ treatment were studied, with BDQ resistance noted in isolates from 2.2% (6/277) of MDR-TB cases, sputum conversion observed in 5 cases, and culture conversion observed in 138 cases within 2 weeks. Another 15 and 30 isolates were excluded from final analysis due to failures in obtaining subcultures and serial isolates, respectively. Of 94 cases yielding serial isolates, 11 exhibited reduced BDQ susceptibility, while 3 of 5 cases with acquired resistance failed to culture convert. Sequence analysis revealed that 6 of 11 BDQ-resistant isolates harbored Rv0678 mutations; no mutations were detected in three other BDQ resistance-associated genes. No significant intergroup difference in culture conversion time was observed.

CONCLUSIONS

MDR-TB patients in China exhibited a low initial BDQ resistance rate. MDR-TB cases with acquired BDQ resistance were at greater risk of treatment failure relative to initially BDQ-resistant cases. Rv0678 mutations accounted for BDQ resistance in this cohort.

Nomogram to predict multidrug-resistant tuberculosis

Background

Multidrug-resistant tuberculosis (MDR-TB) is burgeoning globally, and has been a serious challenge in TB management. Clinically, the ability to identify MDR-TB is still limited, especially in smear-negative TB. The aim of this study was to develop a nomogram for predicting MDR-TB.

Methods

Demographics and clinical characteristics of both MDR-TB and drug-susceptible TB patients were utilized to develop a nomogram for predicting MDR-TB. The LASSO regression method was applied to filter variables and select predictors, and multivariate logistic regression was used to construct a nomogram. The discriminatory ability of the model was determined by calculating the area under the curve (AUC). Moreover, calibration analysis and decision curve analysis (DCA) of the model were performed. This study involved a second analysis of a completed prospective cohort study conducted in a country with a high TB burden.

Results

Five variables of TB patients were selected through the LASSO regression method, and a nomogram was built based on these variables. The predictive model yielded an AUC of 0.759 (95% CI, 0.719–0.799), and in the internal validation, the AUC was 0.757 (95% CI, 0.715–0.793). The predictive model was well-calibrated, and DCA showed that if the threshold probability of MDR-TB was between 70 and 90%, using the proposed nomogram to predict MDR-TB would obtain a net benefit.

Conclusions

In this study, a nomogram was constructed that incorporated five demographic and clinical characteristics of TB patients. The nomogram may be of great value for the prediction of MDR-TB in patients with sputum-free or smear-negative TB.

Tuberculosis - Present Medication and Therapeutic Prospects

BACKGROUND

Tuberculosis (TB) has been present in the history of human civilization since time immemorial and has caused more deaths than any other infectious disease. It is still considered one of the ten most common epidemiologic causes of death in the world. As a transmissible disease, it is initiated by rod-shaped (bacillus) mycobacteria. The management of tuberculosis became possible owing to several discoveries beginning in 1882 with the isolation of the TB bacillus by Robert Koch. The diagnosis of TB was enabled by finding a staining method for TB bacteria identification (1883). It was soon realized that a large-scale policy for the treatment and prevention of tuberculosis was necessary, which resulted in the foundation of International Union against Tuberculosis and Lung Diseases (1902). An antituberculosis vaccine was developed in 1921 and has been in therapeutic use since then. TB treatment regimens have changed over the decades and the latest recommendations are known as Directly Observed Treatment Short-course (DOTS, WHO 1993).

METHODS

A search of bibliographic databases was performed for peer-reviewed research literature. A focused review question and inclusion criteria were applied. Standard tools were used to assess the quality of retrieved papers.

RESULTS

A total of 112 papers were included comprising original publications and reviews. The paper overviews anti-TB drugs according to their mechanism of action. The chemical structure, metabolism and unwanted effects of such drugs have been discussed. The most recent treatment regimens and new drugs, including those in clinical trials, are also presented.

CONCLUSION

Despite a 22% decrease in the tuberculosis fatality rate observed between 2000 and 2015, the disease remains one of the ten prime causes of death worldwide. Increasing bacterial resistance and expensive, prolonged therapies are the main reasons for efforts to find effective drugs or antituberculosis regimens, especially to cure multidrug-resistant tuberculosis.

Molecular characterization of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates identifies local transmission of infection in Kuwait, a country with a low incidence of TB and MDR-TB

Background

Increasing incidence of multidrug-resistant Mycobacterium tuberculosis infections is hampering global tuberculosis control efforts. Kuwait is a low-tuberculosis-incidence country, and ~ 1% of M. tuberculosis strains are resistant to rifampicin and isoniazid (MDR-TB). This study detected mutations in seven genes predicting resistance to rifampicin, isoniazid, pyrazinamide, ethambutol and streptomycin in MDR-TB strains. Sequence data were combined with spoligotypes for detecting local transmission of MDR-TB in Kuwait.

Methods

Ninety-three MDR-TB strains isolated from 12 Kuwaiti and 81 expatriate patients and 50 pansusceptible strains were used. Phenotypic drug susceptibility was determined by MGIT 460 TB/960 system. Mutations conferring resistance to rifampicin, isoniazid, pyrazinamide, ethambutol and streptomycin were detected by genotype MTBDRplus assay and/or PCR sequencing of three rpoB regions, katG codon 315 (katG315) + inhA regulatory region, pncA, three embB regions and rpsL + rrs-500–900 regions. Spoligotyping kit was used, spoligotypes were identified by SITVIT2, and phylogenetic tree was constructed by using MIRU-VNTRplus software. Phylogenetic tree was also constructed from concatenated sequences by MEGA7 software. Additional PCR sequencing of gidB and rpsA was performed for cluster isolates.

Results

Pansusceptible isolates contained wild-type sequences. Mutations in rpoB and katG and/or inhA were detected in 93/93 and 92/93 MDR-TB strains, respectively. Mutations were also detected for pyrazinamide resistance, ethambutol resistance and streptomycin resistance in MDR-TB isolates in pncA, embB and rpsL + rrs, respectively. Spoligotyping identified 35 patterns with 18 isolates exhibiting unique patterns while 75 isolates grouped in 17 patterns. Beijing genotype was most common (32/93), and 11 isolates showed nine orphan patterns. Phylogenetic analysis of concatenated sequences showed unique patterns for 51 isolates while 42 isolates grouped in 16 clusters. Interestingly, 22 isolates in eight clusters by both methods were isolated from TB patients typically within a span of 2 years. Five of eight clusters were confirmed by additional gidB and rpsA sequence data.

Conclusions

Our study provides the first insight into molecular epidemiology of MDR-TB in Kuwait and identified several potential clusters of local transmission of MDR-TB involving 2–6 subjects which had escaped detection by routine surveillance studies. Prospective detection of resistance-conferring mutations can identify possible cases of local transmission of MDR-TB in low MDR-TB settings.

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.

Demographic profile, clinical and microbiological predictors of mortality amongst admitted pediatric TB patients in a tertiary referral tuberculosis hospital

BACKGROUND

Pediatric tuberculosis (TB) constitutes 8% of the total caseload of TB. Children are particularly vulnerable to dissemination of disease and mortality.

AIM

To determine mortality rate, elucidate type of TB, causes and predictors of mortality, if any, in admitted pediatric TB patients.

METHODS

Present retrospective study was conducted in a tertiary referral center over last 6½ year on children who died out of total TB admissions.

RESULTS

Out of total 1380 pediatric (<15 years of age) TB admissions, 74 children died, a mortality rate of 5.36%. Mean age was 11.4 years with highest mortality 47 (63.51%) in patients from 11 to 14 years age group. Significant majority 58 (78.38%) patients were females (p < 0.011). Range of hospital stay was 0-113 days with 7 (9.5%), 9 (12.16%) and 27 (36.48%) children dying on day of admission, next day and 3rd-7th day respectively, therefore a total of 43 (58.11%) died within first week of admission. Most 60 (81.08%) patients belonged to poor socio-economic status. History of contact was present in 12 (16.22%) cases while none had diabetes. 31 (41.89%) patients had sepsis and severe anemia (Hb ≤ 6 g %) was present in 6 (8.11%) patients at admission, out of which 4 died on the same day of admission, even before blood could be arranged. Most patients 68 (91.89%) had pulmonary TB with 25 children having concomitant extrapulmonary involvement, while 4 (5.41%) had meningeal TB and 2 (2.70%) had disseminated TB with HIV. Microbiological confirmation was achieved in 51 (68.92%) (48 PTB and 3 EPTB) cases while 23 (31.08%) were clinically diagnosed. Bilateral extensive fibro-cavitary disease with infiltrations was the commonest. Drug resistance was confirmed in 21 (28.38%) with 2, 5, 8, 5 and 1 patient diagnosed with mono H, RR, MDR, pre-XDR and XDR respectively but results of 9 patients were received posthumously. Treatment given was category 1, category 2 and regimens for drug resistant TB in 24 (32.43%), 29 (39.19%) and 21 (28.37%) cases respectively based on prior history of ATT and drug sensitivity. Adverse drug reactions were noted in 12 (16.21%) cases. Noted immediate causes of mortality were cardio-respiratory failure, sudden pneumothorax, massive hemoptysis, sepsis, extensive pulmonary disease and aspiration pneumonia. The pointers towards mortality include female gender, severe malnutrition, anemia, extensive disseminated disease and drug resistant TB. Ignorance, dependency of children on parents, poor adherence and late referrals into the system lead to delayed diagnosis and initiation of proper regimen based treatment.

CONCLUSION

Early referrals of non-responders and failures to centers equipped with programmatic management facilities are essential for proper, timely management of pediatric TB to reduce mortality.

Use of Second-line Medications and Treatment Outcomes in Children With Tuberculosis in a Single Center From 2007 to 2018

BACKGROUND

The incidence of drug-resistant forms of tuberculosis (DR-TB) and the number of children treated with second-line drugs (SLDs) are increasing. However, limited amount of information is available regarding the use of SLDs in this population.

METHODS

To describe the treatment of pediatric TB with SLDs and factors associated with use of SLDs in children with and without documented DR-TB, records of pediatric TB patients referred to a center in Italy from 2007 to 2018 were reviewed retrospectively.

RESULTS

Of 204 children diagnosed with active TB during the study period, 42 were treated with SLDs because of confirmed or probable drug resistance (42.8%), adverse reactions to first-line drugs (7.1%), central nervous system involvement (11.9%) or unconfirmed possible drug resistance (38.1%). There were no deaths or adverse reactions to SLDs reported. Treatment was successful in 85.2% children treated with first-line drugs and 92.9% children treated with SLDs. After adjusting for calendar period, the only factor associated with DR-TB was <2 years old [odds ratio (OR): 5.24 for <2 years vs. 5-18 years; P = 0.008]. Factors associated with treatment with SLDs were TB at 2 or more sites (OR: 11.30; P < 0.001), extrapulmonary TB (OR: 8.48; P < 0.001) or adverse reactions to first-line drugs (OR: 7.48; P = 0.002). No differences were noted in age or region of origin.

CONCLUSIONS

A substantial proportion of TB children were treated with SLDs. The main reason for using SLDs was failure of a first-line drug regimen, suggesting possible DR-TB and underestimation of DR-TB in children. The use of SLD regimens was associated with a high success rate and good tolerability profile.

Quality of drug-resistant tuberculosis care: Gaps and solutions

Drug-resistant forms of tuberculosis (DR-TB) are a significant cause of global morbidity and mortality and the treatment of DR-TB is characterized by long and toxic regimens that result in low rates of cure. There are few formal studies documenting the quality of DR-TB treatment services provided globally, but the limited data that do exist show there is a quality crisis in the field. This paper reviews current issues impacting quality of care in DR-TB, including within the areas of patient-centeredness, safety, effectiveness and equity. Specific issues affecting DR-TB quality of care include: 1) the use of regimens with limited efficacy, significant toxicity, and high pill burden; 2) standardized treatment without drug susceptibility testing; 3) non-quality assured medications and drug stock outs; 4) lack of access to newer and repurposed drugs; 5) high rates of adverse events coupled with minimal monitoring and management; 6) care provided by multiple providers in the private sector; 7) depression, anxiety, and stress; and 8) stigma and discrimination. The paper discusses potential ways to improve quality in each of these areas and concludes that many of these issues arise from the traditional "public health approach" to TB and will only transformed when a human-rights based approach is put into practice.

Occurrence of disputed rpoB mutations among Mycobacterium tuberculosis isolates phenotypically susceptible to rifampicin in a country with a low incidence of multidrug-resistant tuberculosis

Background

Accurate drug susceptibility testing (DST) of Mycobacterium tuberculosis in clinical specimens and culture isolates to first-line drugs is crucial for diagnosis and management of multidrug-resistant tuberculosis (MDR-TB). Resistance of M. tuberculosis to rifampicin is mainly due to mutations in hot-spot region of rpoB gene (HSR-rpoB). The prevalence of disputed (generally missed by rapid phenotypic DST methods) rpoB mutations, which mainly include L511P, D516Y, H526N, H526L, H526S, and L533P in HSR-rpoB and I572F in cluster II region of rpoB gene, is largely unknown. This study determined the occurrence of all disputed mutations in HSR-rpoB and at rpoB codon 572 in M. tuberculosis strains phenotypically susceptible to rifampicin in Kuwait.

Methods

A total of 242 M. tuberculosis isolates phenotypically susceptible to rifampicin were used. The DST against first-line drugs was performed by Mycobacteria growth indicator tube (MGIT) 960 system. Mutations in HSR-rpoB (and katG codon 315 and inhA-regulatory region for isoniazid resistance) were detected by GenoType MDBDRplus assay. The I572F mutation in cluster II region of rpoB was detected by developing a multiplex allele-specific (MAS)-PCR assay. Results were confirmed by PCR-sequencing of respective loci. Molecular detection of resistance for ethambutol and pyrazinamide and fingerprinting by spoligotyping were also performed for isolates with an rpoB mutation.

Results

Among 242 rifampicin-susceptible isolates, 0 of 130 pansusceptible/monodrug-resistant isolates but 4 of 112 polydrug-resistant isolates contained a disputed rpoB mutation. All 4 isolates were also resistant to isoniazid and molecular screening identified additional resistance to pyrazinamide and ethambutol in one isolate each. In final analysis, 2 of 4 isolates were resistant to all 4 first-line drugs. Spoligotyping showed that the isolates belonged to different M. tuberculosis lineages.

Conclusions

Four of 242 (1.7%) rifampicin-susceptible M. tuberculosis isolates contained a disputed rpoB mutation including 2 isolates resistant to all four first-line drugs. The occurrence of a disputed rpoB mutation in polydrug-resistant M. tuberculosis isolates resistant at least to isoniazid (MDR-TB) suggests that polydrug-resistant strains should be checked for genotypic rifampicin resistance for optimal patient management since the failure/relapse rates are nearly same in isolates with a canonical or disputed rpoB mutation.

Easy-To-Synthesize Spirocyclic Compounds Possess Remarkable in Vivo Activity against Mycobacterium tuberculosis

Society urgently needs new, effective medicines for the treatment of tuberculosis. To kick-start the required hit-to-lead campaigns, the libraries of pharmaceutical companies have recently been evaluated for starting points. The GlaxoSmithKline (GSK) library yielded many high-quality hits, and the associated data were placed in the public domain to stimulate engagement by the wider community. One such series, the spiro compounds, are described here. The compounds were explored by a combination of traditional in-house research and open source methods. The series benefits from a particularly simple structure and a short associated synthetic chemistry route. Many members of the series displayed striking potency and low toxicity, and highly promising in vivo activity in a mouse model was confirmed with one of the analogues. Ultimately the series was discontinued due to concerns over safety, but the associated data remain public domain, empowering others to resume the series if the perceived deficiencies can be overcome.

Incipient and Subclinical Tuberculosis: a Clinical Review of Early Stages and Progression of Infection

Tuberculosis (TB) is the leading infectious cause of mortality worldwide, due in part to a limited understanding of its clinical pathogenic spectrum of infection and disease. Historically, scientific research, diagnostic testing, and drug treatment have focused on addressing one of two disease states: latent TB infection or active TB disease. Recent research has clearly demonstrated that human TB infection, from latent infection to active disease, exists within a continuous spectrum of metabolic bacterial activity and antagonistic immunological responses. This revised understanding leads us to propose two additional clinical states: incipient and subclinical TB. The recognition of incipient and subclinical TB, which helps divide latent and active TB along the clinical disease spectrum, provides opportunities for the development of diagnostic and therapeutic interventions to prevent progression to active TB disease and transmission of TB bacilli. In this report, we review the current understanding of the pathogenesis, immunology, clinical epidemiology, diagnosis, treatment, and prevention of both incipient and subclinical TB, two emerging clinical states of an ancient bacterium.

New drugs and regimens for tuberculosis

Since standardized rifampin-based first-line regimens and fluoroquinolone-based second-line regimens were used to treat tuberculosis (TB), unfortunately without timely modification according to the drug resistance profile, TB and drug-resistant disease are still important public health threats worldwide. Although the last decade has witnessed advances in rapid diagnostic tools and use of repurposed and novel drugs for better managing drug-resistant TB, we need an appropriate TB control strategy and a well-functioning health infrastructure to ensure optimal operational use of rapid tests, judicious use of effective treatment regimens that can be rapidly tailored according to the drug resistance profile and timely management of risk factors and co-morbidities that promote infection and its progression to disease. We searched the published literature to discuss (i) standardized versus individualized therapies, including the choice between a single one-size-fit-all regimen versus different options with different key drugs determined mainly by rapid drug susceptibility testing, (ii) alternative regimens for managing drug-susceptible TB, (iii) evidence for using the World Health Organization (WHO) longer and shorter regimens for multidrug-resistant TB and (iv) evidence for using repurposed and novel drugs. We hope an easily applicable combination of biomarkers that accurately predict individual treatment outcome will soon be available to ultimately guide individualized therapy.

Altered Mycobacterium tuberculosis Cell Wall Metabolism and Physiology Associated With RpoB Mutation H526D

Background:Mycobacterium tuberculosis (Mtb) rpoB mutations are associated with global metabolic remodeling. However, the net effects of rpoB mutations on Mtb physiology, metabolism and function are not completely understood. Based on previous work, we hypothesized that changes in the expression of cell wall molecules in Mtb mutant RpoB 526D lead to changes in cell wall permeability and to altered resistance to environmental stresses and drugs. Methods: The phenotypes of a fully drug-susceptible clinical strain of Mtb and its paired rifampin-monoresistant, RpoB H526D mutant progeny strain were compared. Results: The rpoB mutant showed altered colony morphology, bacillary length and cell wall thickness, which were associated with increased cell wall permeability and susceptibility to the cell wall detergent sodium dodecyl sulfate (SDS) after exposure to nutrient starvation. Relative to the isogenic rifampin-susceptible strain, the RpoB H526D mutant showed altered bacterial cellular metabolic activity and an eightfold increase in susceptibility to the cell-wall acting drug vancomycin. Conclusion: Our data suggest that RpoB mutation H526D is associated with altered cell wall physiology and resistance to cell wall-related stress. These findings are expected to contribute to an improved understanding of the pathogenesis of drug-resistant M. tuberculosis infections.

Antimicrobial molecules in the lung: formulation challenges and future directions for innovation

Inhaled antimicrobials have been extremely beneficial in treating respiratory infections, particularly chronic infections in a lung with cystic fibrosis. The pulmonary delivery of antibiotics has been demonstrated to improve treatment efficacy, reduce systemic side effects and, critically, reduce drug exposure to commensal bacteria compared with systemic administration, reducing selective pressure for antimicrobial resistance. This review will explore the specific challenges of pulmonary delivery of a number of differing antimicrobial molecules, and the formulation and technological approaches that have been used to overcome these difficulties. It will also explore the future challenges being faced in the development of inhaled products and respiratory infection treatment, and identify future directions of innovation, with a particular focus on respiratory infections caused by multiple drug-resistant pathogens.

Rapid diagnosis of pulmonary tuberculosis and detection of drug resistance by combined simultaneous amplification testing and reverse dot blot

Aims

Making a correct and rapid diagnosis is essential for managing pulmonary tuberculosis (PTB), particularly multidrug-resistant tuberculosis. We aimed to evaluate the efficacy of the combination of simultaneous amplification testing (SAT) and reverse dot blot (RDB) for the rapid detection of Mycobacterium tuberculosis (MTB) and drug-resistant mutants in respiratory samples.

Methods

225 suspected PTB and 32 non-TB pulmonary disease samples were collected. All sputum samples were sent for acid-fast bacilli smear, SAT, culture and drug susceptibility testing (DST) by the BACTEC^TM MGIT^TM 960 system. 53 PTB samples were tested by both RDB and DNA sequencing to identify drug resistance genes and mutated sites.

Results

The SAT positive rate (64.9%) was higher than the culture positive rate (55.1%), with a coincidence rate of 83.7%. The sensitivity and specificity of SAT for diagnosing PTB were 66.7% and 100%, respectively, while those for culture were 53.9% and 84.2%, respectively. RDB has high sensitivity and specificity in identifying drug resistance genes and mutated sites. The results of RDB correlated well with those of DST and DNA sequencing, with coincidence rates of 92.5% and 98.1%, respectively.

Conclusions

The combination of SAT and RDB is promising for rapidly detecting PTB and monitoring drug resistance in clinical laboratories.

Recent controversies about MDR and XDR-TB: Global implementation of the WHO shorter MDR-TB regimen and bedaquiline for all with MDR-TB?

Tuberculosis (TB) is now the biggest infectious disease killer worldwide. Although the estimated incidence of TB has marginally declined over several years, it is out of control in some regions including in Africa. The advent of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) threatens to further destabilize control in several regions of the world. Drug-resistant TB constitutes a significant threat because it underpins almost 25% of global TB mortality, is associated with high morbidity, is a threat to healthcare workers and is unsustainably costly to treat. The advent of highly resistant TB with emerging bacillary resistance to newer drugs has raised further concern. Encouragingly, in addition to preventative strategies, several interventions have recently been introduced to curb the drug-resistant TB epidemic, including newer molecular diagnostic tools, new (bedaquiline and delamanid) and repurposed (linezolid and clofazimine) drugs and shorter and individualized treatment regimens. However, there are several controversies that surround the use of new drugs and regimens, including whether, how and to what extent they should be used, and who specifically should be treated so that outcomes are optimally improved without amplifying the burden of drug resistance, and other potential drawbacks, thus sustaining effectiveness of the new drugs. The equipoise surrounding these controversies is discussed and some recommendations are provided.