MPT64 assays for the rapid detection of Mycobacterium tuberculosis

Immunohistochemistry and real-time Polymerase Chain Reaction: importance in the diagnosis of intestinal tuberculosis in a Peruvian population

INTRODUCTION

The diagnosis of intestinal tuberculosis is challenging even nowadays. This study aims to report the positivity rates of new diagnostic methods such as immunohistochemistry and Real-Time Polymerase Chain Reaction in patients with intestinal tuberculosis, as well as describe the pathological and endoscopic features of intestinal tuberculosis in our population.

METHODS

This was a retrospective observational study conducted in patients diagnosed with intestinal tuberculosis, between 2010 to 2023 from the Hospital Nacional Daniel Alcides Carrion and a Private Pathology Center, both located in Peru. Clinical data was obtained, histologic features were independently re-evaluated by three pathologists; and immunohistochemistry and real-time Polymerase Chain Reaction evaluation were performed. The 33 patients with intestinal tuberculosis who fulfilled the inclusion criteria were recruited.

RESULTS

Immunohistochemistry was positive in 90.9% of cases, while real-time Polymerase Chain Reaction was positive in 38.7%. The ileocecal region was the most affected area (33.3%), and the most frequent endoscopic appearance was an ulcer (63.6%). Most of the granulomas were composed solely of epithelioid histiocytes (75.8%). Crypt architectural disarray was the second most frequent histologic finding (78.8%) after granulomas, but most of them were mild.

CONCLUSION

Since immunohistochemistry does not require an intact cell wall, it demonstrates higher sensitivity compared to Ziehl-Neelsen staining. Therefore, it could be helpful for the diagnosis of paucibacillary tuberculosis.

Construction of novel multi-epitope-based diagnostic biomarker HP16118P and its application in the differential diagnosis of Mycobacterium tuberculosis latent infection

Tuberculosis (TB) is an infectious disease that significantly threatens human health. However, the differential diagnosis of latent tuberculosis infection (LTBI) and active tuberculosis (ATB) remains a challenge for clinicians in early detection and preventive intervention. In this study, we developed a novel biomarker named HP16118P, utilizing 16 helper T lymphocyte (HTL) epitopes, 11 cytotoxic T lymphocyte (CTL) epitopes, and 8 B cell epitopes identified from 15 antigens associated with LTBI-RD using the IEDB database. We analyzed the physicochemical properties, spatial structure, and immunological characteristics of HP16118P using various tools, which indicated that it is a hydrophilic and relatively stable alkaline protein. Furthermore, HP16118P exhibited good antigenicity and immunogenicity, while being non-toxic and non-allergenic, with the potential to induce immune responses. We observed that HP16118P can stimulate the production of high levels of IFN-γ+ T lymphocytes in individuals with ATB, LTBI, and health controls. IL-5 induced by HP16118P demonstrated potential in distinguishing LTBI individuals and ATB patients (p=0.0372, AUC=0.8214, 95% CI [0.5843 to 1.000]) with a sensitivity of 100% and specificity of 71.43%. Furthermore, we incorporated the GM-CSF, IL-23, IL-5, and MCP-3 induced by HP16118P into 15 machine learning algorithms to construct a model. It was found that the Quadratic discriminant analysis model exhibited the best diagnostic performance for discriminating between LTBI and ATB, with a sensitivity of 1.00, specificity of 0.86, and accuracy of 0.93. In summary, HP16118P has demonstrated strong antigenicity and immunogenicity, with the induction of GM-CSF, IL-23, IL-5, and MCP-3, suggesting their potential for the differential diagnosis of LTBI and ATB.

Exploring the Potential of Exosomes as Biomarkers in Tuberculosis and Other Diseases

Tuberculosis (TB) is a major cause of morbidity and mortality and remains an important public health issue in developing countries worldwide. The existing methods and techniques available for the diagnosis of TB are based on combinations of laboratory (chemical and biological), radiological, and clinical tests. These methods are sophisticated and laborious and have limitations in terms of sensitivity, specificity, and accuracy. Clinical settings need improved diagnostic biomarkers to accurately detect biological changes due to pathogen invasion and pharmacological responses. Exosomes are membrane-bound vesicles and mediators of intercellular signaling processes that play a significant role in the pathogenesis of various diseases, such as tuberculosis, and can act as promising biomarkers for the monitoring of TB infection. Compared to conventional biomarkers, exosome-derived biomarkers are advantageous because they are easier to detect in different biofluids, are more sensitive and specific, and may be useful in tracking patients' reactions to therapy. This review provides insights into the types of biomarkers, methods of exosome isolation, and roles of the cargo (proteins) present in exosomes isolated from patients through omics studies, such as proteomics. These findings will aid in developing new prognostic and diagnostic biomarkers and could lead to the identification of new therapeutic targets in the clinical setting.

Microfluidic systems for infectious disease diagnostics

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

Epidemiology of Nontuberculous Mycobacteria in Tuberculosis suspects, Southwest of China, 2017-2022

Objectives

This study summarizes the epidemiological characteristics, species distribution, and drug sensitivity of clinical nontuberculous mycobacteria (NTM) isolates at the Public Health Clinical Center of Chengdu, China, from January 2017 to December 2022.

Methods

We retrospectively analyzed data from patients with clinically isolated NTM strains. Chi-square analysis assessed the rate of Mycobacterium strain isolation over 6 years.

Results

The number of samples tested for Mycobacterium tuberculosis (MTB) and/or NTM increased each year, while MTB detection decreased and NTM detection rose significantly each year (P=0.03). The average age of NTM patients was 51 ± 17.53 years, with a 14.1% HIV infection rate. The predominant isolates were Mycobacterium avium-intracellulare (MAC) and M. chelonae/M. abscessus, with 96.4% of cases being of Han ethnicity. Amikacin, moxifloxacin, and clarithromycin were effective against M. avium and M. intracellulare; linezolid, amikacin, and cefoxitin were effective against M. chelonae/M. abscessus. Over 90% of NTM cases originated from the respiratory tract.

Conclusion

The NTM isolation rate in Southwest China has risen in recent years, primarily among elderly patients with a high HIV co-infection rate. The main NTM isolates were MAC and M. chelonae/M. abscessus. Amikacin, moxifloxacin, clarithromycin, and linezolid exhibited strong antibacterial activity against SGM, while amikacin and linezolid displayed relatively better antibacterial activity against RGM. The prevalence of NTM infection may be positively associated with regional economic development and health conditions.

A narrative review of nontuberculous mycobacterial pulmonary disease: microbiology, epidemiology, diagnosis, and management challenges

INTRODUCTION

Nontuberculous mycobacteria (NTM) are a diverse group of mycobacterial species that are ubiquitous in the environment. They are opportunistic pathogens that can cause a range of diseases, especially in individuals with underlying structural lung disease or compromised immune systems.

AREAS COVERED

This paper provides an in-depth analysis of NTM infections, including microbiology, environmental sources and transmission pathways, risk factors for disease, epidemiology, clinical manifestations and diagnostic approaches, guideline-based treatment recommendations, drugs under development, and management challenges.

EXPERT OPINION

Future approaches to the management of NTM pulmonary disease will require therapies that are well tolerated, can be taken for a shorter time period and perhaps less frequently, have few drug-drug interactions, and are active against the various strains of pathogens. As the numbers of infections increase, such therapies will be welcomed by clinicians and patients.

Synthesis of plant-based, self-adjuvanted, dual antigen specific to Mycobacterium tuberculosis as a novel tuberculosis subunit vaccine that elicits immunogenicity in rabbit

OBJECTIVES

The only approved vaccine, Bacillus Calmette Guérin (BCG) used in global tuberculosis (TB) immunization programmes has been very effective in childhood TB but not in adult pulmonary and latent TB. Moreover, the emergence of multi-drug resistance-TB cases demands either to increase efficiency of BCG or replace it with the one with improved efficacy.

RESULTS

A novel combination of two most effective secreted protein antigens specific for Mycobacterium tuberculosis (Mtb), ESAT-6 and MPT-64 (but not present in BCG strains) fused with a cholera toxin B subunit (CTB) and tagged with 6xHis was expressed for the first time in Escherichia coli as well as in transgenic cucumber plants developed using Agrobacterium tumefaciens-mediated transformation. The recombinant fusion protein (His6x.CTB-ESAT6-MPT64) expressed in E. coli was purified by a single-step affinity chromatography and used to produce polyclonal antibodies in rabbit. The transgenic cucumber lines were confirmed by polymerase chain reaction (PCR), Southern blot hybridization, reverse transcriptase PCR (RT-PCR), real-time PCR (qRT-PCR) and expression of recombinant fusion protein by western blot analysis and its quantification by enzyme-linked immunosorbent assay (ELISA). A maximum value of the fusion protein, 478 ng.g^-1 (0.030% of the total soluble protein) was obtained in a transgenic cucumber line. Rabbit immunized orally showed a significant increase in serum IgG levels against the fusion protein as compared to the non-immunized rabbit.

CONCLUSIONS

Stable expression of Mtb antigens with CTB in edible cucumber plants (whose fruits are eaten raw) in sufficient amount possibly would facilitate development of a safe, affordable and orally delivered self-adjuvanted, novel dual antigen based subunit vaccine against TB.

Use of light-emitting diode fluorescence microscopy to detect acid-fast bacilli in sputum as proficient alternative tool in the diagnosis of pulmonary tuberculosis in countries with limited resource settings

Background

Despite recent advances in the development of more sensitive technologies for the diagnosis of tuberculosis (TB), in resource-limited settings, the diagnosis continues to rely on sputum smear microscopy. This is because smear microscopy is simple, cost-efficient and the most accessible tool for the diagnosis of TB. Our study evaluated the performance of light-emitting diode fluorescence microscopy (LED-FM) using auramine/rhodamine (auramine) and the fluorescein di-acetate (FDA) vital stain in the diagnostic of pulmonary TB in Bamako, Mali.

Methods

Sputum smear microscopy was conducted using the FDA and auramine/rhodamine staining procedures on fresh samples using LED-FM to evaluate the Mycobacterium TB (MTB) metabolic activity and to predict contagiousness. Mycobacterial culture assay was utilized as a gold standard method.

Results

Out of 1401 TB suspected patients, 1354 (96.65%) were retrieved from database, which were MTB complex culture positive, and 47 (3.40%) were culture negative (no mycobacterial growth observed). Out of the 1354 included patients, 1343 (95.86%), were acid-fast bacillus (AFB) positive after direct FDA staining, 1352 (96.50%) AFB positive after direct Auramine, and 1354 (96.65%) AFB positive with indirect auramine after digestion and centrifugation. Overall, the FDA staining method has a sensitivity of 98.82%, while the sensitivity of Auramine with direct observation was 99.48%, and 99.56% with the indirect examination.

Conclusion

This study showed that, using fresh sputum both auramine/rhodamine and FDA are highly sensitive methods in diagnosing pulmonary TB and could be easily used in countries with limited resource settings.

Osteoarticular tuberculosis cases in the southwest of China: A 9-year retrospective study

Background

Osteoarticular tuberculosis (TB) is an uncommon form of extrapulmonary TB. In this study, we analyzed the epidemiological characteristics, common sites, and drug resistance profiles of osteoarticular TB infections occurring in southwest China.

Methods

A total of 3,254 cases of patients clinically diagnosed with osteoarticular TB infections between 2013 and 2021 were retrospectively analyzed. Patients' demographic and clinical characteristics were collected. Drug sensitivity testing was performed using the microporous plate ratio method. Chi-squared analysis was used to analyze the rates of and trends in mycobacterial isolates.

Results

Of the 3,254 patients, 1,968 (60.5%) were men and boys, and 1,286 (39.5%) were women and girls; patients' ages ranged from 1 to 91 years, with an average of 42 ± 19.3 years. In terms of disease, 2,261 (69.5%) had spinal TB, mainly thoracic (815, 36%) or lumbar (1,080, 48%); joint TB was found in 874 cases (26.9%), mainly occurring in the knee (263, 30%) or hip (227, 26%); and both spinal and joint TB were observed in 119 cases (3.7%). Drug susceptibility tests were performed on 241 isolated strains of MTB; 70 strains (29.0%) were resistant to at least one drug, and MDR-TB and XDR-TB were observed in 7.1 and 1.2% of strains, respectively.

Conclusions

In southwest China over this period, osteoarticular TB mainly affected middle-aged and young men with poor nutritional status. Patients from ethnic minority areas also accounted for a large proportion of cases. Spinal TB is prone to occur in the lumbar and thoracic vertebrae, and joint TB is prone to occur in the lower limb joints. Additionally, there has been an increasing trend in the number of TB cases over the past 9 years, and drug resistance has also increased.

Detection of Mycobacterium tuberculosis Complex in Sputum Samples Using Droplet Digital PCR Targeting mpt64

Tuberculosis (TB) is one of the top 10 causes of death worldwide. It is challenging to find methods of diagnosis of active pulmonary TB that are sensitive enough to detect cases for proper treatment before unintentional transmission. Droplet digital PCR (ddPCR) is a highly sensitive method to detect genetic material of pathogens, but it has rarely been used for diagnosis of TB. This study compared the sensitivity of ddPCR with that of GeneXpert and AFB smear microscopy in 180 leftover sputum samples from patients suspected of having TB on the basis of clinical symptoms and radiography. Absolute quantification of copy numbers of MTB-specific genes was possible using ddPCR targeting the mpt64 gene. Among the 180 samples, 41.1% were diagnosed as having TB using ddPCR. The sensitivities of AFB smear microscopy, GeneXpert and ddPCR were 41.9%, 82.4% and 100%, respectively. AFB smear microscopy and GeneXpert both had a specificity of 100%, and the specificity of ddPCR was 95.3%. The accuracy of ddPCR (97.2%) is higher than that of GeneXpert (92.7%). This robust ddPCR system could potentially be used as a method for early diagnosis of TB.

Advancing proficiency testing for ultra in resource-limited settings using dried tube specimen: A study by SRL-Uganda

BACKGROUND

Proficiency testing (PT) has been hard to set up due to cost limitations and technical capacity. Conventional Xpert MTB/RIF PT programs use liquid and culture spots which require stringent storage and transportation conditions with cross-contamination chances prevalent. These setbacks prompted the use of dried tube specimens (DTS) for Ultra assay PT. For continuity of PT provision, stability of DTS and compatibility with testing protocols when kept for a long period needs to be established.

METHODS

DTS were prepared from known isolates inactivated using a hot air oven at 85°C. 100μl of bacterial suspensions were aliquoted and dried inside a Biosafety cabinet. Panel validation was done to establish the baseline Deoxyribonucleic acid (DNA) concentration in terms of cycle threshold (Ct) value. DTS aliquots were shipped to participants to test and report within six weeks. The remaining DTS were kept at 2-8°C and room temperature for one year with testing at six months. Twenty (20) DTS samples per set remaining at one year were heated at 55°C for two weeks before testing. The means of the different samples were compared to validation data using paired t-tests. Boxplots were designed to visualize the differences in the medians of the DTS.

RESULTS

Overall mean Ct value increased by 4.4 from the validation to testing after one year at the different storage conditions. Samples heated at 55°C showed a 6.4 Ct difference from validation data. Testing done at six months on 2-8°C stored items showed no statistical difference. At all the remaining testing times and conditions, P-values were less than 0.008 although the absolute mean Ct when compared showed slight increments and accommodated differences for the detection of MTB and rifampicin resistance. Median values for samples stored at 2-8°C were lower compared to those at room temperature.

CONCLUSION

DTS stored at 2-8°C remain more stable for one year compared to higher temperatures and can be consistently used as PT materials in more than one PT round for biannual PT providers.

Relation between Serological Findings and Expression of IL-1β and IL-6 genes in Patients Infected with Mycobacterium Tuberculosis in Iraq

Mycobacterium Tuberculosis (TB) is one of the serious bacterial infections that cause diseases and may lead to death. In this study, 178 individuals were examined for TB infection at Baghdad TB center during the period from 15^th January to 1^st October 2021. Out of 178 participants, 73 were shown to be positive for TB infection, while 105 showed negative results. According to the results, there was no significant variation between infected males and females with TB in comparison to the control group (P>0.05). The results showed that the mean age of the patients for both males and females was in the range of 2-65 years. Additionally, there were significant differences in patients with TB compared to the control group in terms of the weight loss of 8.82 ± 6.75 Kg, red blood cell (RBC) count (3.43 ± 0.56) × 10⁶/μl, white blood cell (WBC) count (3.12 ± 1.57) × 10⁶/μl, platelet count (1.03 ± 0.56) × 10⁶/μl, and hemoglobin level (6.66 ± 1.34) g/dl. A total of 30 TB patients and 50 normal individuals were genotyped to detect the IL-1β rs 114534 gene. The polymerase chain reaction (PCR) was used for exon amplification in region 5 of the ILB1 gene in the TB patients by using specific primers. The finding showed that there was an amplified product of 249bp located in chromosome 2q13-14. A total of 30 TB patients and 50 normal individuals were also genotyped to detect the IL-6 rs 1800795 gene. The PCR was used for amplification of the IL-6 gene in TB patients by using specific primers. The finding showed that there was an amplified product of 431 bp located in chromosome 7p15-p2. The expression of the ILB1 gene was investigated in TB patients and healthy controls by using qPT-PCR. Results showed that there was a high Ct value for patients and controls with a high Ct value of templates, preoperational to the total ribonucleic acid (RNA) concentration and gene expression. The expression of the IL-6 gene was investigated in TB patients and healthy controls by using qPT-PCR. Our findings revealed a high Ct value for patients and controls with a high Ct value of templates, preoperational to the total RNA concentration and gene expression.

Improved Conventional and New Approaches in the Diagnosis of Tuberculosis

Tuberculosis (TB) is a life-threatening infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). Timely diagnosis and effective treatment are essential in the control of TB. Conventional smear microscopy still has low sensitivity and is unable to reveal the drug resistance of this bacterium. The traditional culture-based diagnosis is time-consuming, since usually the results are available after 3–4 weeks. Molecular biology methods fail to differentiate live from dead M. tuberculosis, while diagnostic immunology methods fail to distinguish active from latent TB. In view of these limitations of the existing detection techniques, in addition to the continuous emergence of multidrug-resistant and extensively drug-resistant TB, in recent years there has been an increase in the demand for simple, rapid, accurate and economical point-of-care approaches. This review describes the development, evaluation, and implementation of conventional diagnostic methods for TB and the rapid new approaches for the detection of M. tuberculosis.

Severe Respiratory Failure Due to Pulmonary BCGosis in a Patient Treated for Superficial Bladder Cancer

Intra-vesical instillations with bacillus Calmette-Guerin (BCG) are the established adjuvant therapy for superficial bladder cancer. Although generally safe and well tolerated, they may cause a range of different, local, and systemic complications. We present a patient treated with BCG instillations for three years, who was admitted to our hospital due to fever, hemoptysis, pleuritic chest pain and progressive dyspnea. Chest computed tomography (CT) showed massive bilateral ground glass opacities, partly consolidated, localized in the middle and lower parts of the lungs, bronchial walls thickening, and bilateral hilar lymphadenopathy. PCR tests for SARS-CoV-2 as well as sputum, blood, and urine for general bacteriology—were negative. Initial empiric antibiotic therapy was ineffective and respiratory failure progressed. After a few weeks, a culture of M. tuberculosis complex was obtained from the patient’s specimens; the cultured strain was identified as Mycobacterium bovis BCG. Anti-tuberculous treatment with rifampin (RMP), isoniazid (INH) and ethambutol (EMB) was implemented together with systemic corticosteroids, resulting in the quick improvement of the patient’s clinical condition. Due to hepatotoxicity and finally reported resistance of the BCG strain to INH, levofloxacin was used instead of INH with good tolerance. Follow-up CT scans showed partial resolution of the pulmonary infiltrates. BCG infection in the lungs must be taken into consideration in every patient treated with intra-vesical BCG instillations and symptoms of protracted infection.

Differential Diagnosis of Latent Tuberculosis Infection and Active Tuberculosis: A Key to a Successful Tuberculosis Control Strategy

As an ancient infectious disease, tuberculosis (TB) is still the leading cause of death from a single infectious agent worldwide. Latent TB infection (LTBI) has been recognized as the largest source of new TB cases and is one of the biggest obstacles to achieving the aim of the End TB Strategy. The latest data indicate that a considerable percentage of the population with LTBI and the lack of differential diagnosis between LTBI and active TB (aTB) may be potential reasons for the high TB morbidity and mortality in countries with high TB burdens. The tuberculin skin test (TST) has been used to diagnose TB for > 100 years, but it fails to distinguish patients with LTBI from those with aTB and people who have received Bacillus Calmette–Guérin vaccination. To overcome the limitations of TST, several new skin tests and interferon-gamma release assays have been developed, such as the Diaskintest, C-Tb skin test, EC-Test, and T-cell spot of the TB assay, QuantiFERON-TB Gold In-Tube, QuantiFERON-TB Gold-Plus, LIAISON QuantiFERON-TB Gold Plus test, and LIOFeron TB/LTBI. However, these methods cannot distinguish LTBI from aTB. To investigate the reasons why all these methods cannot distinguish LTBI from aTB, we have explained the concept and definition of LTBI and expounded on the immunological mechanism of LTBI in this review. In addition, we have outlined the research status, future directions, and challenges of LTBI differential diagnosis, including novel biomarkers derived from Mycobacterium tuberculosis and hosts, new models and algorithms, omics technologies, and microbiota.