The bacterial and host factors associated with extrapulmonary dissemination of Mycobacterium tuberculosis

Incidence and Predicting Factors of Opportunistic Infections after Antiretroviral Therapy Initiation among Treatment-naïve Patients with HIV Infection: A Retrospective Cohort Study in A Tertiary Care Hospital

OBJECTIVES

To determine the incidence of opportunistic infections (OIs) and the predictive factors for the development of OIs after antiretroviral therapy (ART) initiation among treatment-naïve patients with HIV infection.

RESULTS

Of 401 HIV-infected patients, 38 (9.5%) HIV-infected patients developed OIs after initiating ART, with an incidence rate of 25.6/1000 person-years. The median time (IQR) from ART initiation to OI occurrence was 26.5 (14-73) days. In multivariate Cox proportional hazard regression, body mass index ≤18.5 kg/m2 (adjusted hazard ratio [aHR] 2.28, 95% confidence interval [CI] 1.18-4.42, P = .015), symptoms at presentation (aHR 13.59, 95% CI 3.24-56.9, P < .001), serum glutamate-pyruvate transaminase >55 U/L (aHR 2.09, 95% CI 1.06-4.15, P = .035), and initiation of a dolutegravir-based regimen (aHR 4.39, 95% CI 1.54-12.48, P = .006) were significantly associated with OIs after ART initiation.

CONCLUSION

OIs after ART initiation are common. Malnutrition, symptomatic presentation, abnormal liver enzymes, and DTG-based regimens are predictors of OI occurrence after ART initiation. Physicians must monitor and appropriately treat OIs after ART initiation.

Association between a single nucleotide polymorphism of the ALOX5 gene and susceptibility to multisystem tuberculosis in a Chinese Han population

BACKGROUND

Host genetic single nucleotide polymorphisms can exert an influence susceptibility to tuberculosis infection. Previous investigations have demonstrated an association between the polymorphism in the ALOX5 gene and a range of diseases, encompassing not only noninfectious conditions like asthma, acute myocardial infarction, and cerebral infarction but also infections caused by various pathogens. However, the relationship between ALOX5 gene polymorphism and susceptibility to tuberculosis has received limited research attention. The ALOX5 gene encodes arachidonic acid 5-lipoxygenase(5-LO), which serves as the initiating catalyst in the generation of the inflammatory mediator leukotriene. Leukotrienes, products derived from the 5-LO pathway, are potent proinflammatory lipid mediators that assume a pivotal role in tuberculosis infections.Consequently, ALOX5 gene variants may be intricately associated with the pathogenesis of tuberculosis. In instances where the host exhibits immunocompromisation, infection with Mycobacterium tuberculosis can impact multiple systems. The involvement of multiple systems significantly augments the complexity of treatment and escalates patient mortality rates. Regrettably, the underlying mechanisms driving multisystem tuberculosis pathogenesis remain enigmatic, with clinicians paying scant attention to this aspect. Although the protein encoded by the ALOX5 gene represents a pivotal enzyme that catalyzes the metabolism of arachidonic acid into LXA4, and thereby plays a significant role in the inflammatory response during tuberculosis infection, studies investigating ALOX5 gene polymorphism and its association with susceptibility to multisystem tuberculosis in the Chinese Han population are exceptionally scarce. Therefore, the primary objective of this study is to comprehensively examine the correlation between ALOX5 gene polymorphisms and susceptibility to tuberculosis within the Chinese Han population, with particular emphasis on multisystemic tuberculosis.

METHODS

A case‒control study design was employed, encompassing 382 individuals with pulmonary tuberculosis and 367 individuals with multisystemic tuberculosis as the case groups, along with 577 healthy controls.Whole blood DNA was extracted from all patients and healthy controls. Subsequently, three tag polymorphisms (rs2029253, rs7896431, rs2115819) within the ALOX5 gene were selectively identified and genotyped.

RESULTS

After adjusting for age and sex, the presence of allele A at rs2029253 exhibited a pronounced association with an elevated risk of TB susceptibility when compared to the tuberculosis group and healthy control group. (ORa: 2.174, 95% CI: 1.827-2.587; Pa<0.001, respectively). Notably, the rs2029253 AG genotype and AA genotype displayed a significantly increased susceptibility to tuberculosis (ORa: 2.236, 95% CI: 1.769-2.825; Pa <0.001 and ORa: 4.577, 95% CI: 2.950-7.100; Pa <0.001, respectively) compared to the GG genotype. Moreover, in the analysis utilizing genetic models, rs2029253 also exhibited a markedly heightened susceptibility to tuberculosis in additive models, dominant models, and recessive models (Pa <0.001). Conversely, no significant association was observed between rs7896431, rs2115819, and tuberculosis. In the subgroup analysis, when comparing the pulmonary tuberculosis group with the healthy control group, we observed no significant disparities in the distribution frequencies of alleles, genotypes, and gene models (additive model, dominant model, and recessive model) for the three tag SNPs, with P-values were >0.05 after adjusting for age and sex. Additionally, we noted that the presence of allele A at rs2029253 was linked to an increased susceptibility to tuberculosis in the multisystemic tuberculosis group relative to the healthy control group (ORa: 2.292, 95% CI: 1.870-2.810; Pa<0.001). Similarly, the rs2029253 AG genotype, AA genotype, and gene models, including the additive model, dominant model, and recessive model, demonstrated a significantly elevated risk of tuberculosis susceptibility.

CONCLUSIONS

The polymorphism in the ALOX5 gene is associated with susceptibility to multisystemic tuberculosis in the Chinese Han population.

Bacteriologically confirmed extrapulmonary tuberculosis and the associated risk factors among extrapulmonary tuberculosis suspected patients in Ethiopia: A systematic review and meta-analysis

BACKGROUND

The actual burden of bacteriologically confirmed extrapulmonary tuberculosis (EPTB) and risk factors in Ethiopia is not well known due to the lack of a strong surveillance system in Ethiopia. Thus, this study was conducted to estimate the pooled prevalence of bacteriologically confirmed EPTB and the associated risk factors among persons suspected to have non-respiratory tuberculosis in Ethiopia.

METHODS

A systematic review and meta-analysis of published studies reporting the prevalence of EPTB from searched electronic databases; Science Direct, PubMed, and Google Scholar was estimated spread across the research periods, nationally, and in different areas, using a fixed-effects model. We used I2 to analyze heterogeneity in the reported prevalence of bacteriologically confirmed extrapulmonary tuberculosis.

RESULTS

After reviewing 938 research articles, 20 studies (19 cross-sectional and 1 retrospective) from 2003 to 2021 were included in the final analyses. The pooled prevalence of bacteriologically confirmed EPTB was 43% (95%CI; 0.34-0.52, I2 = 98.45%). The asymmetry of the funnel plot revealed the presence of publication bias. Specifically the pooled prevalence of bacteriologically confirmed EPTB based on smear microscopy, Xpert MTB/RIF assay, and culture were 22% (95%CI; 0.13-0.30, I2 = 98.56%), 39% (95%CI; 0.23-0.54, I2 = 98.73%) and 49% (95%CI; 0.41-0.57, I2 = 96.43%) respectively. In this study, a history of pulmonary tuberculosis (PTB) contact with PTB patients, contact with live animals, consumption of raw milk, HIV-positive, male, and lower monthly income, were found to be independently associated with bacteriologically confirmed EPTB.

CONCLUSION

Ethiopia has a high rate of bacteriologically confirmed EPTB. A history of previous PTB, being HIV-positive and having contact with PTB patients were the most reported risk factors for EPTB in the majority of studies. Strengthening laboratory services for EPTB diagnosis should be given priority to diagnose EPTB cases as early as possible.

Epidemiological and Cytokine Profile of Patients with Pulmonary and Extrapulmonary Tuberculosis in a Population of the Brazilian Amazon

Several factors are associated with the development of different clinical forms of tuberculosis (TB). The present study evaluated epidemiological variables and cytokine levels in samples from 89 patients with TB (75 with pulmonary TB and 14 with extrapulmonary TB) and 45 controls. Cytokines were measured by flow cytometry (Human Th1/Th2/Th17 Cytometric Bead Array kit). The TB group had a higher frequency of individuals who were 39 years of age or older, married, with primary education or illiterate and had a lower family income (p < 0.05). All individuals with extrapulmonary TB reported that they were not working, and the main reasons were related to disease symptoms or treatment. The levels of IFN-γ (OR = 4.06) and IL-4 (OR = 2.62) were more likely to be elevated in the TB group (p = 0.05), and IFN-γ levels were lower in patients with extrapulmonary TB compared to those with pulmonary TB (OR = 0.11; p = 0.0050). The ROC curve was applied to investigate the diagnostic accuracy of IFN-γ levels between the different clinical forms of tuberculosis, resulting in high AUC (0.8661; p < 0.0001), sensitivity (93.85%) and specificity median (65.90%), suggesting that IFN-γ levels are useful to differentiate pulmonary TB from extrapulmonary TB. The dysregulation of pro- and anti-inflammatory cytokine levels represent a risk for the development of TB and contribute to the pathogenesis of the disease, especially variation in IFN-γ levels, which may determine protection or risk for extrapulmonary TB.

A case of endocarditis and spondylodiscitis associated with Mycobacterium tuberculosis

Tuberculosis (TB) is a global health problem, in which the majority of cases occur in population-dense developing countries. Despite advances in various diagnostic TB modalities, extrapulmonary TB remains a challenge due to complexities related to its diagnostic approach. Hereby, we present a rare case of endocarditis and spondylodiscitis associated with Mycobacterium tuberculosis (MTB). This case report highlighted the challenges faced in diagnosing blood culture-negative infective endocarditis (BCNIE). We also emphasized the importance of considering MTB as etiology of BCNIE, particularly in endemic TB areas.

Genetic diversity and characterization of M. tuberculosis isolates causing extrapulmonary tuberculosis in Bangladesh

Tuberculosis (TB) remains one of the leading causes of death and Bangladesh ranks 7th among the highest TB burden countries. Though molecular epidemiological data for pulmonary TB (PTB) have previously been described in Bangladesh, data on the molecular characterization and clinical association with different lineages among extrapulmonary TB (EPTB) is lacking. The aim of the study was to investigate the molecular characterization and lineage distribution of M. tuberculosis isolates obtained from patients with EPTB in Bangladesh. Between November 2015 and March 2017, a total of 1,340 EPTB specimens including lymph node, pus, tissue, ascitic fluid, cerebrospinal fluid, pleural fluid, abscess wall, urine etc. were collected from four tertiary care hospitals in Dhaka city, Bangladesh. Among the specimens, 141 were found positive on solid culture. Molecular characterization of the 141 isolates was done by deletion analysis, spoligotyping and Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeats (MIRU-VNTR) analysis. Among the 141 isolates, 80 (56.7%) were found as 'modern' and the remaining 61 (43.3%) were 'ancestral' type. Spoligotyping results revealed 91 distinct patterns of which 74 isolates were unique and the remaining 67 were divided into 17 distinct clusters. East African- Indian (EAI) lineage was the most predominant, comprising 26 (18.4%) isolates, followed by the Beijing lineage (14.2%). 15-loci MIRU-VNTR analysis revealed that 132 isolates (93.5%) had unique patterns, whereas only 9 (6.5%) isolates were grouped into 4 distinct clusters. In conclusion, the study findings provide a first insight into genetic diversity of EPTB isolates in Bangladesh. The present study demonstrated that 'modern' strains were more prevalent among the EPTB cases, while EAI lineages were predominantly circulating in this region.

Targeting endogenous gaseous signaling molecules as novel host-directed therapies against tuberculosis infection

Tuberculosis (TB) is a chronic pulmonary disease caused by Mycobacterium tuberculosis which is a major cause of morbidity and mortality worldwide. Due to the complexity of disease and its continuous global spread, there is an urgent need to improvise the strategies for prevention, diagnosis, and treatment. The current anti-TB regimen lasts for months and warrants strict compliance to clear infection and to minimize the risk of development of multi drug-resistant tuberculosis. This underscores the need to have new and improved therapeutics for TB treatment. Several studies have highlighted the unique ability of Mycobacterium tuberculosis to exploit host factors to support its survival inside the intracellular environment. One of the key players to mycobacterial disease susceptibility and infection are endogenous gases such as oxygen, nitric oxide, carbon monoxide and hydrogen sulfide. Nitric oxide and carbon monoxide as the physiological gaseous messengers are considered important to the outcome of Mycobacterium tuberculosis infection. The role of hydrogen sulfide in human tuberculosis is yet not fully elucidated, but this gas has been shown to play a significant role in bacterial respiration, growth and pathogenesis. This review will focus on the host factors majorly endogenous gaseous signaling molecules which contributes to Mycobacterium tuberculosis survival inside the intracellular environment and highlight the potential therapeutic targets.

Gaps in Study Design for Immune Parameter Research for Latent Tuberculosis Infection: A Systematic Review

Background

Immune parameters (IP) have been extensively studied to distinguish between latent tuberculosis (LTBI) and active tuberculosis (TB).

Objective

To determine the IP associated with LTBI, compared to active TB and individuals not infected by M. tuberculosis published in literature.

Methods

We conducted a systematic search using Google Scholar and PubMed databases, combining the MeSH terms latent tuberculosis, Mycobacterium tuberculosis, cytokines, and biological markers, with the free terms, biomarkers and cytokines. Spanish, English, and Portuguese articles comparing the concentration of IP associated with LTBI, either in plasma/serum or in vitro, in adults and nonimmunocompromised versus individuals with TB or without M. tuberculosis infection between 2006 July and 2018 July were included. Two blinded reviewers carried out the searches, read the abstracts, and selected the articles for analysis. Participants' information, diagnostic criteria, IP, detection methods, and biases were collected.

Results

We analyzed 36 articles (of 637 abstracts) with 93 different biomarkers in different samples. We found 24 parameters that were increased only in active TB (TGF-α, CSF3, CSF2, CCL1 [I-309], IL-7, TGF-β1, CCL3 [MIP-1α], sIL-2R, TNF-β, CCL7 [MCP-3], IFN-α, fractalkine, I-TAG, CCL8 [MCP-2], CCL21 [6Ckine], PDGF, IL-22, VEGF-A, LXA4, PGE2, PGF2α, sCD163, sCD14, and 15-Epi-LXA4), five were elevated in LTBI (IL-5, IL-17F, IL-1, CCL20 [MIP-3α], and ICAM-1), and two substances were increased among uninfected individuals (IL-23 and basic FGF). We found high heterogeneity between studies including failure to account for the time/illness of the individuals studied; varied samples and protocols; different clinical classification of TB; different laboratory methods for IP detection, which in turn leads to variable units of measurement and assay sensitivities; and selection bias regarding TST and booster effect. None of the studies adjusted the analysis for the effect of ethnicity.

Conclusions

It is mandatory to harmonize the study of immune parameters for LTBI diagnosis. This systematic review is registered with PROSPERO CRD42017073289.

Changes in the NK Cell Repertoire Related to Initiation of TB Treatment and Onset of Immune Reconstitution Inflammatory Syndrome in TB/HIV Co-infected Patients in Rio de Janeiro, Brazil-ANRS 12274

Tuberculosis (TB) is the most common comorbidity and the leading cause of death among HIV-infected individuals. Although the combined antiretroviral therapy (cART) during TB treatment improves the survival of TB/HIV patients, the occurrence of immune reconstitution inflammatory syndrome (IRIS) in some patients poses clinical and scientific challenges. This work aimed to evaluate blood innate lymphocytes during therapeutic intervention for both diseases and their implications for the onset of IRIS. Natural killer (NK) cells, invariant NKT cells (iNKT), γδ T cell subsets, and in vitro NK functional activity were characterized by multiparametric flow cytometry in the following groups: 33 TB/HIV patients (four with paradoxical IRIS), 27 TB and 25 HIV mono-infected subjects (prior to initiation of TB treatment and/or cART and during clinical follow-up to 24 weeks), and 25 healthy controls (HC). Concerning the NK cell repertoire, several activation and inhibitory receptors were skewed in the TB/HIV patients compared to those in the other groups, especially the HCs. Significantly higher expression of CD158a (p = 0.025), NKp80 (p = 0.033), and NKG2C (p = 0.0076) receptors was detected in the TB/HIV IRIS patients than in the non-IRIS patients. Although more NK degranulation was observed in the TB/HIV patients than in the other groups, the therapeutic intervention did not alter the frequency during follow-up (weeks 2-24). A higher frequency of the γδ T cell population was observed in the TB/HIV patients with inversion of the Vδ2⁺/Vδ2^- ratio, especially for those presenting pulmonary TB, suggesting an expansion of particular γδ T subsets during TB/HIV co-infection. In conclusion, HIV infection impacts the frequency of circulating NK cells and γδ T cell subsets in TB/HIV patients. Important modifications of the NK cell repertoire were observed after anti-TB treatment (week 2) but not during the cART/TB follow-up (weeks 6-24). An increase of CD161⁺ NK cells was related to an unfavorable outcome. Despite the low number of cases, a more preserved NK cell profile was detected in IRIS patients previous to treatment, suggesting a role for these cells in IRIS onset. Longitudinal evaluation of the NK repertoire showed the impact of TB treatment and implicated these cells in TB pathogenesis in TB/HIV co-infected patients.

Uncommon testicular localization of Disseminated TB: a case report from Mozambique

Tuberculosis (TB) of the testicle is a rarely reported and poorly described disease localization. There are no well-defined clinical features suggestive of testicular TB, which makes the diagnosis difficult to establish, especially in low-income settings like Mozambique, where TB is endemic and often associated with HIV-infection; both considered leading causes of death worldwide. We reported the case of a 45-year-old male, HIV positive, naïve to antiretroviral treatment, admitted to the Department of Medicine of the Central Hospital of Beira to investigate chronic enlargement of the testicles.

Demographic risk factors for extra-pulmonary tuberculosis among adolescents and adults in Saudi Arabia

Despite low infectious potential of extrapulmonary tuberculosis (EPTB), it poses significant clinical challenges in terms of diagnosis and treatment monitoring. Understanding the main demographical risk factors for disease characteristics of EPTB plays a crucial role in speeding up diagnosis process and improving overall clinical experience. The aim of this study was to investigate the main demographical and clinical risk factors for EPTB among adults and adolescents for the first time in Saudi Arabia. A cross-sectional multicenter study was carried out on a collection of 902 extrapulmonary Mycobacterium tuberculosis complex (MTBC) isolates with demographical and clinical data. All isolates were subjected to spoligotyping and 24-loci based MIRU-VNTR typing. The association between two potential variables was assessed using odd ratios (OR) calculations. Independent risk factors for EPTB and diseases characteristics of EPTB were identified using multivariate regression model analyses. Gender was found to be significantly associated with lymph node, gastrointestinal, central nervous system and urogenital TB. Lymph node TB showed statistical association to age group below 25 years, non-Saudis and South East Asian ethnicity. While gastrointestinal TB demonstrated an association with patients above 60 years old, and Saudis. Multivariate analysis showed that gender is an independent risk factor to urogenital TB (p 0.03) and lymph node TB (p 0.005). On the other hands, South Asian (p 0.01) and South East Asian (p 0.03) ethnicities were both identified as independent risk factors significantly associated with EPTB. MTBC lineages, site of infections, gender, HIV and smear positivity showed no significant association. Nationwide qualitative-studies are highly warranted in the future to further understand the main demographic risk factors for disease characteristics of EPTB.

The role of epigenetics, bacterial and host factors in progression of Mycobacterium tuberculosis infection

Tuberculosis (TB) infection caused by Mycobacterium tuberculosis (Mtb) is still a persistent global health problem, particularly in developing countries. The World Health Organization (WHO) reported a mortality rate of about 1.8 million worldwide due to TB complications in 2015. The Bacillus Calmette-Guérin (BCG) vaccine was introduced in 1921 and is still widely used to prevent TB development. This vaccine offers up to 80% protection against various forms of TB; however its efficacy against lung infection varies among different geographical settings. Devastatingly, the development of various forms of drug-resistant TB strains has significantly impaired the discovery of effective and safe anti-bacterial agents. Consequently, this necessitated discovery of new drug targets and novel anti-TB therapeutics to counter infection caused by various Mtb strains. Importantly, various factors that contribute to TB development have been identified and include bacterial resuscitation factors, host factors, environmental factors and genetics. Furthermore, Mtb-induced epigenetic changes also play a crucial role in evading the host immune response and leads to bacterial persistence and dissemination. Recently, the application of GeneXpert MTB/RIF^® to rapidly diagnose and identify drug-resistant strains and discovery of different molecular markers that distinguish between latent and active TB infection has motivated and energised TB research. Therefore, this review article will briefly discuss the current TB state, highlight various mechanisms employed by Mtb to evade the host immune response as well as to discuss some modern molecular techniques that may potentially target and inhibit Mtb replication.

Mycobacterium tuberculosis strains induce strain-specific cytokine and chemokine response in pulmonary epithelial cells

M. tuberculosis F15/LAM4/KZN has been associated with high transmission rates of drug resistant tuberculosis in the KwaZulu-Natal province of South Africa. The current study elucidated the cytokine/chemokine responses induced by representatives of the F15/LAM4/KZN and other dominant strain families in pulmonary epithelial cells. Multiplex cytokine analyses were performed at 24, 48 and 72h post infection of the A549 pulmonary epithelial cell line with the F15/LAM4/KZN, F28, F11, Beijing, Unique and H37Rv strains at an MOI of ∼10:1. Twenty-three anti- and pro-inflammatory cytokines/chemokines were detected at all-time intervals. Significantly high concentrations of IL-6, IFN-γ, TNF-α and G-CSF at 48h, and IL-8, IFN-γ, TNF-α, G-CSF and GM-CSF at 72h, were induced by the F28 and F15/LAM4/KZN strains, respectively. Lower levels of cytokines/chemokines were induced by either the Beijing or Unique strains at all three time intervals. All strains induced up-regulation of pathogen recognition receptors (PRRs) (TLR3 and TLR5) while only the F15/LAM4/KZN, F11 and F28 strains induced significant differential expression of TLR2 compared to the Beijing, Unique and H37Rv strains. The low induction of cytokines in epithelial cells by the Beijing strain correlates with its previously reported hypervirulent properties. High concentrations of cytokines and chemokines required for early protection against M. tuberculosis infections induced by the F15/LAM4/KZN and F28 strains suggests a lower virulence of these genotypes compared to the Beijing strain. These findings demonstrate the high diversity in host cytokine/chemokine response to early infection of pulmonary epithelial cells by different strains of M. tuberculosis.

Tuberculous Lymphadenitis and Parotitis

Tuberculous lymphadenitis is the most common extrapulmonary manifestation of disseminated tuberculosis (TB). It is considered to be the local manifestation of the systemic disease that has disseminated to local lymph nodes, but a high index of suspicion is needed for the diagnosis, because there are several infectious and noninfectious diseases that can mimic the same clinical picture. In recent years, different diagnostic methods have been introduced, including fine-needle aspiration cytology, which has emerged as a simple outpatient diagnostic procedure that replaced the complete excisional node biopsy, and a number of molecular methods which have greatly improved diagnostic accuracy. This chapter covers the most actual knowledge in terms of epidemiology, clinical manifestations, pathogenesis, and treatment and emphasizes current trends in diagnosis of tuberculous lymphadenitis. TB parotid gland involvement is extremely rare, even in countries in which TB is endemic. Because of the clinical similarity, parotid malignancy and other forms of parotid inflammatory disease always take priority over the rarely encountered TB parotitis when it comes to differential diagnosis. As a result, clinicians often fail to make a timely diagnosis of TB parotitis when facing a patient with a slowly growing parotid lump. This chapter highlights the most important features of this uncommon disease.