Management of Tuberculosis Infection: Current Situation, Recent Developments and Operational Challenges

Impact of media coverage on the transmission dynamics of TB with vaccines and treatment

Tuberculosis (TB) is one of the deadly infectious diseases affecting millions of individuals throughout the world. The main objective of this study is to investigate the impact of media coverage on the transmission dynamics of TB with vaccine and treatment strategy using mathematical model analysis. In the qualitative analysis of the proposed model we proved the existence, uniqueness, positivity, and boundedness of the model solutions, investigated both the disease-free and endemic equilibrium points, computed the basic and effective reproduction numbers using next generation matrix approach, analyzed the stability analysis of the equilibrium points, the backward bifurcation using the Castillo-Chavez and Song theorem and we re-formulated the corresponding optimal control problem and analyzed by applying the Pontryagin's Minimum Principle. In the model quantitative (numerical) analysis part, we performed the model parameters sensitivity analysis and carried out numerical simulation to verify the qualitative analysis results. The findings of the study indicate that if the reproduction number is less than one, the solution converges to the disease-free state, signifying the asymptotic stability of the TB-free steady state. Moreover, the existence of a backward bifurcation shows that the disease-free equilibrium coexists with one or more endemic equilibria, even when the basic reproduction number is less than 1. Furthermore, it is found that as media efficacy increases, the disease infection rate decreases, which consequently leads to an increase in prevention and treatment control strategies.

Diagnosis and treatment of latent tuberculosis infection among household contacts in inland Bahia, Brazil: a cross-sectional follow-up study

BACKGROUND

The diagnosis and treatment of latent tuberculosis infection (LTBI) are crucial for tuberculosis (TB) control. Household contacts (HHC) of patients with pulmonary TB are at a high risk of LTBI due to their close proximity to source cases.

OBJECTIVE

To describe the diagnosis and treatment of LTBI among HHC.

DESIGN AND SETTING

This cross-sectional follow-up study was conducted in the municipality of Paulo Afonso, northeastern Brazil, between 2013 and 2022.

METHODS

We retrieved secondary data from the medical records of HHC who were followed up at a specialized referral center for TB. LTBI prevalence estimates were calculated and are presented with 95% confidence intervals (CIs).

RESULTS

In total, 622 HHC were screened for LTBI, with 620 evaluated using the tuberculin skin test (TST). Of these, 40 (6.5%) did not return for TST reading. The overall prevalence of LTBI was 53.1% (95% CI: 49-57.1%), with a high prevalence among females and individuals aged 25-34 years. The overall LTBI treatment initiation rate was 26.1% (95%CI: 21.5-31.3%), and 64.2% (95%CI: 53.3-73.8%) of HHC who initiated treatment completed their course.

CONCLUSION

This study revealed a high prevalence of LTBI among HHC, particularly among women and individuals aged 25-34 years, underscoring the ongoing TB transmission within the community. Only 26.1% of the diagnosed HHC initiated treatment, with approximately 64% completing their course. This highlights the challenges in managing LTBI and emphasizes the need for targeted screening and interventions for high-risk groups.

Tuberculosis Causing a Pectoral Mass Mimicking Malignancy: A Rare Presentation of Tuberculosis

Tuberculosis is an infectious disease that may involve all systems, with the respiratory system being the most commonly affected. Tuberculosis of the chest wall and its structures is rare, in which malignancy and abscess may be counted among possible differential diagnoses. In this case report, a patient with pectoral muscle tuberculosis will be presented. A 47-year-old female with a history of hypertension and epilepsy was evaluated for a rapidly enlarging painful mass under the left breast, which was later considered a cold abscess. The routine laboratory tests showed elevated C-reactive protein and erythrocyte sedimentation rate. Further radiological imaging with computed tomography confirmed the mass with chest wall involvement. The performed biopsy revealed granulomatous inflammation and subsequent tests confirmed acid-fast bacteria, with later confirmation of Mycobacterium tuberculosis in the culture. The patient was treated with an intensive regimen of anti-tuberculosis (TB) drugs consisting of isoniazid, rifampin, pyrazinamide, and ethambutol. After nine months, including a treatment extension due to possible vertebral involvement, the patient showed no symptoms and is under follow-up. Extrapulmonary TB, particularly musculoskeletal TB, comes with many diagnostic challenges due to its nonspecific symptoms. Tissue sampling remains the most important aspect of diagnosis confirmation and treatment planning; hence, TB should always be kept in mind among possible differential diagnoses, especially in endemic regions.

Key challenges in TB drug discovery: A perspective

Over the past 2000 years, tuberculosis (TB) has been responsible for more deaths than any other infectious disease. In recent years, there has been a recovery of research and development (R&D) efforts focused on TB drugs. This is driven by the pressing need to combat the global spread of the disease and develop improved therapies for both drug-sensitive and drug-resistant strains. Many new TB drug candidates have recently entered clinical trials, marking the beginning of a rebirth in this area after decades of neglect. The problem is that very few of the hundreds of compounds identified each year as potential anti-TB drugs really make it to the clinical development stage. This perspective focuses on the primary obstacles and approaches involved in the development of new medications for TB. This will help medicinal chemists better understand TB drug challenges and develop novel drug candidates.

Management of cutaneous tuberculosis in hand - Rare and disabling: A case report

INTRODUCTION AND IMPORTANCE

Cutaneous Tuberculosis (CTB), elicited by the Mycobacterium tuberculosis complex, manifests dermatologically. The scarcity of bacilli within CTB lesions renders their detection challenging. This study presents a case of CTB, underscoring its rarity and the potential for severe complications that can deteriorate patient quality of life. It aims to highlight the importance of CTB identification in dermatological diagnoses due to its capacity to cause considerable morbidity and affect patients' psychosocial health.

CASE PRESENTATION

An 18-year-old patient presented with a painful, well-defined reddish plaque on the right palm, originating five years prior, accompanied by contractures of the middle finger. The tender lesion, characterized by an irregular surface, exhibited purulent discharge upon light touch through fissures along its periphery. Management involved necrotomy, debridement, and tissue biopsy for diagnostic and reconstructive purposes.

CLINICAL DISCUSSION

CTB exhibits a wide range of clinical presentations, often resembling other dermatological infections, which complicates its diagnosis. Accurate diagnosis necessitates an integrated approach involving clinical assessment, the tuberculin skin test, histopathological analysis, and bacteriological investigations. The therapeutic regimen includes multidrug anti-tuberculosis treatment, with surgical intervention reserved for specific cases.

CONCLUSION

Long-term complications of untreated CTB encompass significant contractures, scarring, and the onset of carcinomas and sarcomas. Prompt diagnosis facilitates timely and effective treatment, averting these sequelae and yielding high patient satisfaction.

Activation of host nucleic acid sensors by Mycobacterium: good for us or good for them?

Although the importance of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) sensors in controlling viral infection is well established, their role in promoting an effective immune response to pathogens other than viruses is less clear. This is particularly true for infections with mycobacteria, as studies point to both protective and detrimental roles for activation of nucleic acid sensors in controlling a mycobacterial infection. Some of the contradiction likely stems from the use of different model systems and different mycobacterial species/strains as well as from which nucleic acid sensors were studied and what downstream effectors were evaluated. In this review, we will describe the different nucleic acid sensors that have been studied in the context of mycobacterial infections, and how the different studies compare. We conclude with a section on how nucleic acid sensor agonists have been used therapeutically and what further information is needed to enhance their potential as therapeutic agents.

PCR Development for Analysis of Some Type II Toxin-Antitoxin Systems, relJK, mazEF3, and vapBC3 Genes, in Mycobacterium tuberculosis and Mycobacterium bovis

Toxin-Antitoxin (TA) systems are some small genetic modules in bacteria that play significant roles in resistance and tolerance development to antibiotics. Whole genome sequencing (WGS) is an effective method to analyze TA systems in pathogenic Mycobacteria. However, this study aimed to use a simple and inexpensive PCR-Sequencing approach to investigate the type II TA system. Using data from the WGS of Mycobacterium tuberculosis (M. tuberculosis) strain H37Rv and Mycobacterium bovis (M. bovis) strain BCG, primers specific to the relJK, mazEF3, and vapBC3 gene families were designed by Primer3 software. Following that, a total of 90 isolates were examined using the newly developed PCR assay, consisting of 64 M. tuberculosis and 26 M. bovis isolates, encompassing both 45 rifampin-sensitive and 45 rifampin-resistant strains. Finally, 28 isolates (including 14 rifampin-resistant isolates) were sent for sequencing, and their sequences were aligned and compared to the mentioned reference sequences. The amplicons size of mazEF3, relJK, and vapBC3 genes were 825, 875, and 934 bp, respectively. Furthermore, all tested isolates showed the specific amplicons for these TA families. To evaluate the specificity of the primers, PCR was performed on S. aureus and E.coli isolates. None of the examined samples had the desired amplicons. Therefore, the primers had acceptable specificity. The results indicated that the developed PCR-Sequencing approach can be used to effectively investigate certain types of TA systems. Considering high costs of WGS and difficulty in interpreting its results, such a simple and inexpensive method is beneficial in the evaluation of TA systems in Mycobacteria.

Dual-specificity phosphatase 5-mediated fatty acid oxidation promotes Mycobacterium bovis BCG -induced inflammatory responses

Mycobacterium tuberculosis (Mtb) reprograms FAs metabolism of macrophages during infection and affects inflammatory reaction eventually, however, the mechanism remains poorly understood. Here we show that Mycobacterium bovis (BCG) induces DUSP5 expression through TLR2-MAPKs signaling pathway and promotes fatty acid oxidation (FAO). Silencing DUSP5 by adeno-associated virus vector (AAV) ameliorates lung injury and DUSP5 knockdown reduces the expression of IL-1β, IL-6 and inactivated NF-κB signaling in BCG-infected macrophages. Of note, DUSP5 specific siRNA increases the content of free fatty acids (FFAs) and triglyceride (TG), but represses the expression of FAO associated enzymes such as CPT1A and PPARα, suggesting DUSP5 mediated FAO during BCG infection. Moreover, Inhibiting FAO by pharmacological manner suppresses IL-1β, IL-6, TNF-α expression and relieves lung damage. Taken together, our data indicates DUSP5 mediates FAO reprogramming and promotes inflammatory response to BCG infection.

Beyond latent and active tuberculosis: a scoping review of conceptual frameworks

There is growing recognition that tuberculosis (TB) infection and disease exists as a spectrum of states beyond the current binary classification of latent and active TB. Our aim was to systematically map and synthesize published conceptual frameworks for TB states. We searched MEDLINE, Embase and EMcare for review articles from 1946 to September 2023. We included 40 articles that explicitly described greater than two states for TB. We identified that terminology, definitions and diagnostic criteria for additional TB states within these articles were inconsistent. Eight broad conceptual themes were identified that were used to categorize TB states: State 0: Mycobacterium tuberculosis (Mtb) elimination with innate immune response (n = 25/40, 63%); State I: Mtb elimination by acquired immune response (n = 31/40, 78%); State II: Mtb infection not eliminated but controlled (n = 37/40, 93%); State III: Mtb infection not controlled (n = 24/40, 60%); State IV: bacteriologically positive without symptoms (n = 26/40, 65%); State V: signs or symptoms associated with TB (n = 39/40, 98%); State VI: severe or disseminated TB disease (n = 11/40, 28%); and State VII: previous history of TB (n = 5/40, 13%). Consensus on a non-binary framework that includes additional TB states is required to standardize scientific communication and to inform advancements in research, clinical and public health practice.

Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS) Syndrome Induced by Primary Anti-tubercular Medication: A Case Report

Drug reaction with eosinophilia and systemic syndrome (DRESS) is a life-threatening hypersensitivity reaction of the skin and visceral organs caused by exposure to certain drugs, often with a latency period of two to eight weeks. A 20-year-old man, previously diagnosed with pulmonary tuberculosis (TB) one month ago and receiving treatment with isoniazid, rifampicin, pyrazinamide, and ethambutol (HRZE regimen), presented with symptoms including a maculopapular rash, fever, elevated transaminase levels, an increased white blood cell count with eosinophilia, hepatomegaly, and lymphadenopathy. The patient experienced recovery upon cessation of drug use and was administered corticosteroids and supportive therapeutic interventions. Individuals diagnosed with pulmonary TB who are undergoing treatment with first-line anti-tubercular medications have a heightened susceptibility to DRESS. The timely identification and cessation of the offending agent can effectively mitigate mortality.