Clinical implications of the global multidrug-resistant tuberculosis epidemic

Panorama of Bacterial Infections Caused by Epidemic Resistant Strains

Antimicrobial resistance (AMR) represents a critical obstacle to public health worldwide, due to the high incidence of strains resistant to available antibiotic therapies. In recent years, there has been a significant increase in the prevalence of resistant epidemic strains, associated with this, public health authorities have been alarmed about a possible scenario of uncontrolled dissemination of these microorganisms and the difficulty in interrupting their transmission, as nosocomial pathogens with resistance profiles previously considered sporadic. They become frequent bacteria in the community. In addition, therapy for infections caused by these pathogens is based on broad-spectrum antibiotic therapy, which favors an increase in the tolerance of remaining bacterial cells and is commonly associated with a poor prognosis. In this review, we present the current status of epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), MDR Mycobacterium tuberculosis, extended-spectrum β-lactamase-producing Enterobacterales (ESBL), Klebsiella pneumoniae carbapenemase (KPC), and—New Delhi Metallo-beta-lactamase-producing Pseudomonas aeruginosa (NDM).

Nontuberculous Mycobacterial Pulmonary Disease: Clinical Epidemiologic Features, Risk Factors, and Diagnosis: The Nontuberculous Mycobacterial Series

Nontuberculous mycobacterial pulmonary disease (NTM-PD) continues to impose a significant clinical burden of disease on susceptible patients. The incidence of NTM-PD is rising globally, but it remains a condition that is challenging to diagnose and treat effectively. This review provides an update on the global epidemiologic features, risk factors, and diagnostic considerations associated with the management of NTM-PD.

Personalised Medicine for Tuberculosis and Non-Tuberculous Mycobacterial Pulmonary Disease

Personalised medicine, in which clinical management is individualised to the genotypic and phenotypic data of patients, offers a promising means by which to enhance outcomes in the management of mycobacterial pulmonary infections. In this review, we provide an overview of how personalised medicine approaches may be utilised to identify patients at risk of developing tuberculosis (TB) or non-tuberculous mycobacterial pulmonary disease (NTM-PD), diagnose these conditions and guide effective treatment strategies. Despite recent technological and therapeutic advances, TB and NTM-PD remain challenging conditions to diagnose and treat. Studies have identified a range of genetic and immune factors that predispose patients to pulmonary mycobacterial infections. Molecular tests such as nucleic acid amplification assays and next generation sequencing provide a rapid means by which to identify mycobacterial isolates and their antibiotic resistance profiles, thus guiding selection of appropriate antimicrobials. Host-directed therapies and therapeutic drug monitoring offer ways of tailoring management to the clinical needs of patients at an individualised level. Biomarkers may hold promise in differentiating between latent and active TB, as well as in predicting mycobacterial disease progression and response to treatment.

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.

Nomogram for individualized prediction of incident multidrug-resistant tuberculosis after completing pulmonary tuberculosis treatment

The purposes of this study were to construct a comprehensive nomogram for providing a simple, precise and personalized prediction of incident multidrug-resistant tuberculosis (MDR-TB) after completing pulmonary tuberculosis treatment (CPTBT). A matched case–control study (1:2 ratios) was performed between 2005 and 2018. A multivariable Cox regression analysis was used to evaluate independent predictors of incident MDR-TB after the CPTBT. A comprehensive nomogram was developed based on the multivariable Cox model. Overall, 1, 836 participants were included in this study. We developed and validated a simple-to-use nomogram that predicted the individualized risk of incident MDR-TB by using 10 parameters after the CPTBT. The concordance index of this nomogram was 0.833 [95% confidence interval (CI) 0.807–0.859] and 0.871 (95% CI 0.773–0.969) for the training and validation sets, respectively, which indicated adequate discriminatory power. The calibration curves for the risk of incident MDR-TB showed an optimal agreement between nomogram prediction and actual observation in the training and validation sets, respectively. The high sensitivity and specificity of nomogram was indicated by using a receiver operating characteristic curve analysis. Through this clinic tool, TB control executives could more precisely monitor, estimate and intervene the risk of incident MDR-TB among individuals with CPTBT.

Some New Hydrazone Derivatives Bearing the 1,2,4-Triazole Moiety as Potential Antimycobacterial Agents

Objectives

The aim of this study was to synthesize, characterize, and screen some new 1-(4-((2-(4-substitutedphenyl)hydrazono)methyl)phenyl)-1H-1,2,4-triazole derivatives for their antimycobacterial activities.

Materials and Methods

The target compounds (2a-h) were gained by condensation of 4-(1H-1,2,4-triazol-1-yl)benzaldehyde with appropriate phenylhydrazines. Their structures were elucidated by IR, ¹H-NMR, and mass spectrometry. The antimycobacterial activities of the compounds were determined in vitro against Mycobacterium tuberculosis H37Rv.

Results

The biological assay results showed that the methylsulfonyl-substituted derivative 2f displayed the highest antimycobacterial activity in this series.

Conclusion

Although the methylsulfonyl-substituted derivative exhibited significant antimycobacterial activity, none of the synthesized compounds was as effective as isoniazid, rifampin, ethambutol, and ciprofloxacin against M. tuberculosis.

Multi-drug resistant Mycobacterium tuberculosis in Port Harcourt, Nigeria

Background

In past years, much focus has been on tackling the scourge and spread of tuberculosis worldwide. The recent emergence of multi-drug resistant (MDR) tuberculosis has, however, negatively threatened progress made so far. Nigeria ranks fourth out of the 22 high tuberculosis burden countries in the world and has the highest burden of tuberculosis in Africa. It is therefore necessary to monitor the MDR tuberculosis situation in the country.

Objectives

This study set out to assess the proportions of MDR tuberculosis in patients attending six directly observed treatment short-course centres in Port Harcourt, Nigeria, from October 2015 to October 2016.

Methods

Six hundred and nine participants between the ages of 18 and 75 years were enrolled in this study and comprised suspected and newly diagnosed tuberculosis cases. Sputum samples obtained from the participants were screened for the presence of Mycobacterium tuberculosis using standard culture and phenotypic biochemical techniques, and drug susceptibility testing was carried out using the 1% proportion conventional method.

Results

Of the 609 participants enrolled, 30 (4.9%) were confirmed as M. tuberculosis-positive cases. A high prevalence of drug resistant tuberculosis was noted in this study (14/30, 46.7%), with 26.7% of isolates resistant to streptomycin. MDR tuberculosis, defined as being resistant to isoniazid and rifampicin, was detected in only one case (3.3%).

Conclusion

This study reports a low rate of MDR tuberculosis and contributes to the sparse data on drug resistant tuberculosis in Nigeria.

New agents for the treatment of drug-resistant Mycobacterium tuberculosis

Inadequate dosing and incomplete treatment regimens, coupled with the ability of the tuberculosis bacilli to cause latent infections that are tolerant of currently used drugs, have fueled the rise of multidrug-resistant tuberculosis (MDR-TB). Treatment of MDR-TB infections is a major clinical challenge that has few viable or effective solutions; therefore patients face a poor prognosis and years of treatment. This review focuses on emerging drug classes that have the potential for treating MDR-TB and highlights their particular strengths as leads including their mode of action, in vivo efficacy, and key medicinal chemistry properties. Examples include the newly approved drugs bedaquiline and delaminid, and other agents in clinical and late preclinical development pipeline for the treatment of MDR-TB. Herein, we discuss the challenges to developing drugs to treat tuberculosis and how the field has adapted to these difficulties, with an emphasis on drug discovery approaches that might produce more effective agents and treatment regimens.