Recurrent TB: relapse or reinfection? The effect of HIV in a general population cohort in Malawi

Decreased IL-1 β Secretion as a Potential Predictor of Tuberculosis Recurrence in Individuals Diagnosed with HIV

Background: The mechanisms of the formation of immunological competence against tuberculosis (TB), and especially those associated with HIV co-infection, remain poorly understood. However, there is an urgent need for risk recurrence predictive biomarkers, as well as for predictors of successful treatment outcomes. The goal of the study was to identify possible immunological markers of TB recurrence in individuals with HIV/TB co-infection. Methods: The plasma levels of IFN-γ, TNF-α, IL-10, and IL-1β (cytokines which play important roles in the immune activation and protection against Mycobacterium tuberculosis) were measured using ELISA EIA-BEST kits. The cytokine concentrations were determined using a standard curve obtained with the standards provided by the manufacturer of each kit. Results: A total of 211 individuals were enrolled in the study as follows: 62 patients with HIV/TB co-infection, 52 with HIV monoinfection, 52 with TB monoinfection, and 45 healthy donors. Out of the 62 patients with HIV/TB, 75.8% (47) of patients were newly diagnosed with HIV and TB, and 24.2% (15) displayed recurrent TB and were newly diagnosed with HIV. Decreased levels of IFN-γ, TNF-α, and IL-10 were observed in patients with HIV/TB when compared with HIV and TB patients. However, there was no difference in IFN-γ, TNF-α, or IL-10 secretion between both HIV/TB groups. At the same time, an almost 4-fold decrease in Il-1β levels was detected in the HIV/TB group with TB recurrence when compared with the HIV/TB group (p = 0.0001); a 2.8-fold decrease when compared with HIV patients (p = 0.001); and a 2.2-fold decrease with newly diagnosed TB patients (p = 0.001). Conclusions: Significantly decreased Il-1β levels in HIV/TB patients' cohort with secondary TB indicate that this cytokine can be a potential biomarker of TB recurrence.

Risk factors for pulmonary tuberculosis recurrence, relapse and reinfection: a systematic review and meta-analysis

BACKGROUND

The rate of pulmonary tuberculosis (TB) recurrence is substantial. Identifying risk factors can support the development of prevention strategies.

METHODS

We retrieved studies published between 1 January 1980 and 31 December 2022 that assessed factors associated with undifferentiated TB recurrence, relapse or reinfection. For factors reported in at least four studies, we performed random-effects meta-analysis to estimate a pooled relative risk (RR). We assessed heterogeneity, risk of publication bias and certainty of evidence.

RESULTS

We included 85 studies in the review; 81 documented risk factors for undifferentiated recurrence, 17 for relapse and 10 for reinfection. The scope for meta-analyses was limited given the wide variety of factors studied, inconsistency in control for confounding and the fact that only few studies employed molecular genotyping. Factors that significantly contributed to moderately or strongly increased pooled risk and scored at least moderate certainty of evidence were: for undifferentiated recurrence, multidrug resistance (MDR) (RR 3.49; 95% CI 1.86 to 6.53) and fixed-dose combination TB drugs (RR 2.29; 95% CI 1.10 to 4.75) in the previous episode; for relapse, none; and for reinfection, HIV infection (RR 4.65; 95% CI 1.71 to 12.65). Low adherence to treatment increased the pooled risk of recurrence 3.3-fold (95% CI 2.37 to 4.62), but the certainty of evidence was weak.

CONCLUSION

This review emphasises the need for standardising methods for TB recurrence research. Actively pursuing MDR prevention, facilitating retention in treatment and providing integrated care for patients with HIV could curb recurrence rates. The use of fixed-dose combinations of TB drugs under field conditions merits further attention.

PROSPERO REGISTRATION NUMBER

CRD42018077867.

Recurrence of pulmonary tuberculosis in India: Findings from the 2019-2021 nationwide community-based TB prevalence survey

Recurrent Tuberculosis patients contribute to a significant proportion of TB burden in India. A nationwide survey was conducted during 2019-2021 across India among adults to estimate the prevalence of TB. A total of 322480 individuals were screened and 1402 were having TB. Of this, 381 (27.1%) had recurrent TB. The crude prevalence (95% CI) of recurrent TB was 118 (107-131) per 100,000 population. The median duration between episodes of TB was 24 months. The proportion of drug resistant TB was 11.3% and 3.6% in the recurrent group and new TB patients respectively. Higher prevalence of recurrent TB was observed in elderly, males, malnourished, known diabetics, smokers, and alcohol users. (p<0.001). To prevent TB recurrence, all treated tuberculosis patients must be followed at least for 24 months, with screening for Chest X-ray, liquid culture every 6 months, smoking cessation, alcohol cessation, nutritional interventions and good diabetic management.

Relationship between smoking and tuberculosis recurrence: A systematic review and meta-analysis

INTRODUCTION

Of the problems in tuberculosis (TB) control program is the recurrence of this disease. In some studies, smoking has been reported as the most important risk factor. Therefore, the present study aimed at examining the association between smoking and tuberculosis recurrence using meta-analysis.

METHODS

To report the findings of this meta-analysis, we used PRISMA. The protocol of this study has been recorded in PROSPERO. The research question has been formulated based on PICO, and the search was performed using both MeSH and non-MeSH keywords. After screening and selecting the articles and evaluating their quality using the NOS checklist, the overall estimate of the odds ratio of tuberculosis recurrence in smokers was assessed with a 95% confidence interval.

RESULTS

Fourteen studies met the inclusion criteria. The total number of samples in the group of patients with tuberculosis recurrence was 1988 with 855 (43%) smokers, and in the group of patients affected by tuberculosis without recurrence, it was 27,226 with 7503 (27.56%) smokers. In 13 studies, the odds ratio of tuberculosis recurrence was higher in smokers; this difference was statistically significant in 12 of them. Combining the results of these 14 studies, the odds ratio of tuberculosis recurrence in smokers was 2.10 times higher, using the random effects model (95% CI:1.69, 2.61).

CONCLUSION

Based on the results of study present, smoking increases the risk of tuberculosis recurrence. Therefore, to eradicate tuberculosis by 2030, more serious interventions should be taken to quit smoking, which in turn reduces the incidence of tuberculosis.

Contribution of Reinfection to Annual Rate of Tuberculosis Infection (ARI) and Incidence of Tuberculosis Disease

BACKGROUND

Modeling studies have concluded that 60-80% of tuberculosis (TB) infections result from reinfection of previously infected persons. The annual rate of infection (ARI), a standard measure of the risk of TB infection in a community, may not accurately reflect the true risk of infection among previously infected persons. We constructed a model of infection and reinfection with Mycobacterium tuberculosis to explore the predictive accuracy of ARI and its effect on disease incidence.

METHODS

We created a deterministic simulation of the progression from TB infection to disease and simulated the prevalence of TB infection at the beginning and end of a theoretical year of infection. We considered 10 disease prevalence scenarios ranging from 100/100 000 to 1000/100 000 in simulations where TB exposure probability was homogeneous across the whole simulated population or heterogeneously stratified into high-risk and low-risk groups. ARI values, rates of progression from infection to disease, and the effect of multiple reinfections were obtained from published studies.

RESULTS

With homogeneous exposure risk, observed ARI values produced expected numbers of infections. However, when heterogeneous risk was introduced, observed ARI was seen to underestimate true ARI by 25-58%. Of the cases of TB disease that occurred, 36% were among previously infected persons when prevalence was 100/100 000, increasing to 79% of cases when prevalence was 1000/100 000.

CONCLUSIONS

Measured ARI underestimates true ARI as a result of heterogeneous population mixing. The true force of infection in a community may be greater than previously appreciated. Hyperendemic communities likely contribute disproportionally to the global TB disease burden.

Tuberculosis reinfection and relapse in eastern China: A prospective study using whole-genome sequencing

OBJECTIVES

Tuberculosis recurrence after an initial successful treatment episode can occur from either reinfection or relapse. In a population-based sample and whole genome sequencing (WGS) in eastern China, we aimed to evaluate risk factors for tuberculosis recurrence, and assess the proportion of recurrence due to either reinfection or relapse.

METHODS

Successfully treated pulmonary tuberculosis patients with sputum culture positive results were recruited from five cities in Jiangsu Province from 2013-2015 and followed for two years for tuberculosis recurrence. Among patients developing a second tuberculosis episode, WGS was performed to distinguish relapse or reinfection through a distance threshold of 6-single-nucleotide polymorphisms (SNP). We analyzed risk factors for recurrence and epidemiological characteristics of different types of recurrent patients.

RESULTS

Of 1,897 successful treated tuberculosis patients, 7.4% (141/1879) developed recurrent tuberculosis. Compared with non-recurrent tuberculosis, patients were at higher risk of recurrence in older age (Adjusted Odds Ratio [AOR], 1.02 for each additional year; 95% CI, 1.01-1.03, P=0.003), patients previously treated for tuberculosis (AOR=2.22; 95% CI, 1.52-3.26, P<0.001), or with bilateral cavities (AOR, 1.56; 95% CI, 1.05-2.32, P=0.029). Among 27.0% (38/141) recurrent tuberculosis patients with successfully sequenced pairs, relapse was substantially more common than reinfection (71.1% versus 28.9%, P=0.014).

CONCLUSIONS

Endogenous relapse was significantly more common than exogenous reinfection in the first two years after treatment in eastern China. Prioritization of high-risk groups for recurrence, such as the elderly, with a previous tuberculosis diagnosis, or with bilateral cavities, may provide opportunities to reduce post-tuberculosis morbidity.

Risk factors for types of recurrent tuberculosis (reactivation versus reinfection): A global systematic review and meta-analysis

BACKGROUND

The purpose of this meta-analysis (PROSPERO number: CRD42021243204) is to perform extensive and penetrating analyses on the risk factors associated with reactivation or reinfection.

METHODS

We searched PubMed and Embase using search terms. Risk factors (including sex, length of time between first onset and recurrent diagnosis, extrapulmonary tuberculosis, sputum smear, pulmonary cavity, Beijing family strains, diabetes, HIV infection, history of imprisonment, and immigration) were analyzed. The pooled risk ratio (RR) and 95% confidence interval (CI) were calculated with STATA 15.1. Heterogeneity was evaluated by I² and P values.

RESULTS

The meta-analysis included 25 studies with a total of 1,477 patients. After subgroup analysis, sensitivity analysis, and testing for publication bias, it was concluded that time spanning less than two years (RR=1.56, 95% CI: 1.33-1.85) was a risk factor for endogenous reactivation, while coinfection with HIV (RR=0.72, 95% CI: 0.63-0.83), Beijing family genotype (RR=0.46, 95% CI: 0.32-0.67), history of imprisonment (RR=0.36, 95% CI: 0.16-0.81) and immigration (RR=0.66, 95% CI: 0.53-0.82) were associated with exogenous reinfection.

CONCLUSIONS

The recurrence interval is a risk factor for the endogenous reactivation of tuberculosis. Infection with Beijing family strains, coinfection with HIV, imprisonment, and immigration contribute to the risk of exogenous reinfection.

Predictors of Drug-Resistant Tuberculosis among High-Risk Population Diagnosed under National Program Conditions in the Littoral Region, Cameroon

Multiple drug resistance TB (MDR-TB) has greatly jeopardized the effective control of tuberculosis in Africa. This study is aimed at determining the incidence and predictors of drug resistant-TB amongst bacteriologically diagnosed cases in the Littoral region of Cameroon. This was a descriptive cross-sectional survey conducted from January 2016 to December 2017. A total of 1665 participants were enrolled from 32 diagnostic and treatment centers (DTCs) in the Littoral region. Demographic, clinical, socioeconomic, and behavioral data were obtained using a pretested structured questionnaire. Drug susceptibility testing was performed using Gene Xpert MTB/RIF assay and line probe assay (LPA). Consent was obtained from participant/guidance. Data analysis was carried with SPSS version 21. Univariate and multiple logistic regression was performed at 5% significance level. The incidence of rifampicin and MDR-TB was 86 (5.2%) and 75 (4.5%), respectively. More (11.3%) cases of drug resistance were diagnosed in 2016 compared to 2017 (3.7%). Eleven (0.7%) were resistant to rifampicin only. A total of 19 (4.4%) cases of rifampicin resistance were detected from newly diagnosed cases and 67 (5.4%) from previously retreated cases. Pre-XDR-TB was detected in 2 (2.7%) of the MDR-TB cases amongst whom 1 (1.3%) was extensive drug resistance TB (XDR-TB). Age greater than 60 years old (OR = 4.98, p = 0.047), being married (OR = 1.91, p = 0.006), being currently incarcerated (OR = 1.74, p = 0.027), and having contact with known TB cases (OR = 1.88, p = 0.007) were associated to MDR-TB in a univariate analysis. This study highlights the declining rates of TB drug resistance in the region over the years probably due to the introduction of Gene Xpert that results in early detection of RR-TB. It also shows that age greater than 60 years, being married, and incarcerated are predictors of drug resistant-TB, while the year of patient enrolment and previous exposure to TB treatment were independent predictors of drug resistance in the Littoral region of Cameroon.

A Mycobacterium tuberculosis Specific IgG3 Signature of Recurrent Tuberculosis

South Africa has the highest prevalence of HIV and tuberculosis (TB) co-infection globally. Recurrent TB, caused by relapse or reinfection, makes up the majority of TB cases in South Africa, and HIV infected individuals have a greater likelihood of developing recurrent TB. Given that TB remains a leading cause of death for HIV infected individuals, and correlates of TB recurrence protection/risk have yet to be defined, here we sought to understand the antibody associated mechanisms of recurrent TB by investigating the humoral response in a longitudinal cohort of HIV co-infected individuals previously treated for TB with and without recurrent disease during follow-up, in order to identify antibody correlates of protection between individuals who do not have recurrent TB and individuals who do. We used a high-throughput, “systems serology” approach to profile biophysical and functional characteristics of antibodies targeting antigens from Mycobacterium tuberculosis (Mtb). Differences in antibody profiles were noted between individuals with and without recurrent TB, albeit these differences were largely observed close to the time of re-diagnosis. Individuals with recurrent TB had decreased Mtb-antigen specific IgG3 titers, but not other IgG subclasses or IgA, compared to control individuals. These data point to a potential role for Mtb-specific IgG3 responses as biomarkers or direct mediators of protective immunity against Mtb recurrence.

Defective expansion and function of memory like natural killer cells in HIV+ individuals with latent tuberculosis infection

Purpose

Tuberculosis (TB) is the leading cause of infectious disease related mortality, and only 10% of the infected individuals develop active disease. The likelihood of progression of latent tuberculosis infection (LTBI) to active TB disease is high in HIV infected individuals. Identification of HIV+ individuals at risk would allow treating targeted population, facilitating completion of therapy for LTBI and prevention of TB development. NK cells have an important role in T cell independent immunity against TB, but the exact role of NK cell subsets in LTBI and HIV is not well characterized.

Methods

In this study, we compared the expansion and function of memory like NK cells from HIV-LTBI+ individuals and treatment naïve HIV+LTBI+ patients in response to Mtb antigens ESAT-6 and CFP-10.

Results

In freshly isolated PBMCs, percentages of CD3^-CD56⁺ NK cells were similar in HIV+LTBI+ patients and healthy HIV-LTBI+ individuals. However, percentages of CD3^-CD56⁺CD16⁺ NK cells were higher in healthy HIV-LTBI+ individuals compared to HIV+LTBI+ patients. HIV infection also inhibited the expansion of memory like NK cells, production of IL-32α, IL-15 and IFN-γ in response to Mtb antigens in LTBI+ individuals.

Conclusion

We studied phenotypic, functional subsets and activation of memory like-NK cells during HIV infection and LTBI. We observed that HIV+LTBI+ patients demonstrated suboptimal NK cell and monocyte interactions in response to Mtb, leading to reduced IL-15, IFN-γ and granzyme B and increased CCL5 production. Our study highlights the effect of HIV and LTBI on modulation of NK cell activity to understand their role in development of interventions to prevent progression to TB in high risk individuals.

Alveolar macrophages from persons living with HIV show impaired epigenetic response to Mycobacterium tuberculosis

Persons living with HIV (PLWH) are at increased risk of tuberculosis (TB). HIV-associated TB is often the result of recent infection with Mycobacterium tuberculosis (Mtb) followed by rapid progression to disease. Alveolar macrophages (AM) are the first cells of the innate immune system that engage Mtb, but how HIV and antiretroviral therapy (ART) impact on the anti-mycobacterial response of AM is not known. To investigate the impact of HIV and ART on the transcriptomic and epigenetic response of AM to Mtb, we obtained AM by bronchoalveolar lavage from 20 PLWH receiving ART, 16 control subjects who were HIV-free (HC), and 14 subjects who received ART as pre-exposure prophylaxis (PrEP) to prevent HIV infection. Following in-vitro challenge with Mtb, AM from each group displayed overlapping but distinct profiles of significantly up- and down-regulated genes in response to Mtb. Comparatively, AM isolated from both PLWH and PrEP subjects presented a substantially weaker transcriptional response. In addition, AM from HC subjects challenged with Mtb responded with pronounced chromatin accessibility changes while AM obtained from PLWH and PrEP subjects displayed no significant changes in their chromatin state. Collectively, these results revealed a stronger adverse effect of ART than HIV on the epigenetic landscape and transcriptional responsiveness of AM.

High Rates of Recurrent Tuberculosis Disease: A Population-level Cohort Study

Background

Retreatment tuberculosis (TB) disease is common in high-prevalence settings. The risk of repeated episodes of recurrent TB is unknown. We calculated the rate of recurrent TB per subsequent episode by matching individual treatment episodes over a period of 13 years.

Methods

All recorded TB episodes in Cape Town between 2003 and 2016 were matched by probabilistic linkage of personal identifiers. Among individuals with a first episode notified in Cape Town and who completed their prior treatment successfully we estimated the recurrence rate stratified by subsequent episode and HIV status. We adjusted person-time to background mortality by age, sex, and HIV status.

Results

A total of 292 915 TB episodes among 263 848 individuals were included. The rate of recurrent TB was 16.4 per 1000 person-years (95% CI, 16.2–16.6), and increased per subsequent episode (8.4-fold increase, from 14.6 to 122.7 per 1000 from episode 2 to 6, respectively). These increases were similar stratified by HIV status. Rates among HIV positives were higher than among HIV negatives for episodes 2 and 3 (2- and 1.5-fold higher, respectively), and the same thereafter.

Conclusions

TB recurrence rates were high and increased per subsequent episode, independent of HIV status. This suggests that HIV infection is insufficient to explain the high burden of recurrence; it is more likely due to a high annual risk of infection combined with an increased risk of infection or progression to disease associated with a previous TB episode. The very high recurrence rates would justify increased TB surveillance of patients with >1 episode.

'TB is a disease which hides in the body': Qualitative data on conceptualisations of tuberculosis recurrence among patients in Zambia and South Africa

The WHO estimates 58 million people experienced one or more TB disease episodes between 2000 and 2018. These 'former TB patients' are at greater risk of future TB infection and death than TB naïve people. Additionally, former TB patients experience social, psychological, and physiological difficulties after microbiological cure. Drawing on semi-structured interviews collected with 28 people from communities in Zambia (n = 8) and South Africa (n = 2) between October 2018 and March 2019, we describe their perceptions of having two or more TB episodes. Utilising a discursive analytic approach, we interrogated how participants conceptualise their risk of disease recurrence. Despite being surprised by subsequent TB episodes, participants utilised their bodily experiences of TB signs and symptoms alongside their experiential knowledge of health systems processes to procure timely diagnosis and care. Yet, many participants were unable to resume social and economic participation. Experiences of multiple TB episodes and correlating social, economic, and physiological vulnerabilities, challenged participants biomedical understanding of TBs curability. Through notions of dirt and 'staining', participants conceptualise TB as a sinister, malicious presence they are bound to encounter time and again. Health providers should discuss the risk of TB recurrence with patients and promote prevention, early detection, and diagnosis of TB disease.

HIV TB coinfection - perspectives from India

Introduction: HIV and tuberculosis (TB) are two of the most challenging infections faced by humanity and place immense burden on health care systems worldwide. Both HIV and TB impact one another's progression.Areas covered: HIV is the most important risk factor for progression of latent TB to active disease. TB is the most common cause of death among People Living with HIV (PLHIV). Timely detection of TB among PLHIV and screening for HIV among TB patients, early initiation of ART and ATT among coinfected persons, provision of CPT and TB Preventive therapy along with control of air-borne infection are some of the key activities to reduce morbidity and mortality among coinfected persons. Despite many challenges, the collaboration between two programs has yielded good results and globally more than 7.3 million lives of PLHIV have been saved globally through scale-up of collaborative TB/HIV activities since 2005. The review looked into key features of both programs that are the collaboration strategies and challenges that still need to be addressed.Expert opinion: The overarching principle for effective implementation of collaborative activities is integration of the TB and HIV national programs right from policy making to service delivery and monitoring.

Assortative social mixing and sex disparities in tuberculosis burden

Globally, men have higher tuberculosis (TB) burden but the mechanisms underlying this sex disparity are not fully understood. Recent surveys of social mixing patterns have established moderate preferential within-sex mixing in many settings. This assortative mixing could amplify differences from other causes. We explored the impact of assortative mixing and factors differentially affecting disease progression and detection using a sex-stratified deterministic TB transmission model. We explored the influence of assortativity at disease-free and endemic equilibria, finding stronger effects during invasion and on increasing male:female prevalence (M:F) ratios than overall prevalence. Variance-based sensitivity analysis of endemic equilibria identified differential progression as the most important driver of M:F ratio uncertainty. We fitted our model to prevalence and notification data in exemplar settings within a fully Bayesian framework. For our high M:F setting, random mixing reduced equilibrium M:F ratios by 12% (95% CrI 0-30%). Equalizing male case detection there led to a 20% (95% CrI 11-31%) reduction in M:F ratio over 10 years-insufficient to eliminate sex disparities. However, this potentially achievable improvement was associated with a meaningful 8% (95% CrI 4-14%) reduction in total TB prevalence over this time frame.

Phenotype Definition for "Resisters" to Mycobacterium tuberculosis Infection in the Literature-A Review and Recommendations

Tuberculosis (TB) remains a worldwide problem. Despite the high disease rate, not all who are infected with Mycobacterium Tuberculosis (Mtb) develop disease. Interferon-γ (IFN-γ) specific T cell immune assays such as Quantiferon and Elispot, as well as a skin hypersensitivity test, known as a tuberculin skin test, are widely used to infer infection. These assays measure immune conversion in response to Mtb. Some individuals measure persistently negative to immune conversion, despite high and prolonged exposure to Mtb. Increasing interest into this phenotype has led to multiple publications describing various aspects of these responses. However, there is a lack of a unified "resister" definition. A universal definition will improve cross study data comparisons and assist with future study design and planning. We review the current literature describing this phenotype and make recommendations for future studies.

Comparison and lessons learned from neglected tropical diseases and tuberculosis

Currently, tuberculosis (TB) is the leading cause of death from a single infectious agent and accounts for over one-third of all HIV-related deaths. However, research and programmatic funding have lagged far behind investments for many other diseases. For about a century, the current Bacillus Calmette-Guérin vaccine has been the only effective vaccine and is only effective in preventing severe disease in children; the first new therapeutic drug for TB in over 40 years was brought to market a few years ago; and until 10 years ago, diagnosis of TB depended on a century-old testing technique. This paper relates TB to neglected tropical diseases (NTDs) and highlights shared characteristics. The aim is to elevate awareness of TB within the framework of NTDs and gain insights from successes in addressing NTDs and how these lessons can be applied to help global health programs change the trajectory of the TB epidemic. A literature review was conducted to compare TB to NTDs and highlight lessons learned from NTD control that can be applied to the TB epidemic. Common features of NTDs include underlying burden of disease, influence and effect on poverty and development, and neglect through political will and funding. There are overarching principles for the design and implementation of NTD control programs that could be applied to ending TB.

Asymptomatic Malaria Co-infection of HIV-Infected Adults in Nigeria: Prevalence of and Impact on Cognition, Mood, and Biomarkers of Systemic Inflammation

BACKGROUND

HIV and malaria are associated with immunological perturbations and neurocognitive disorders even when asymptomatic. However, the effect of asymptomatic malaria (AM) in HIV-infected adults on neurocognitive impairment (NCI) is not well understood. This study investigated the biomarkers of systemic inflammation and neurocognition in dually infected Nigerian adults.

METHODS

We assessed the HIV and AM status of 269 adults and measured their global and domain-specific neurocognition and depression using standardized measures. Blood levels of sCD14 and sCD163 were also measured.

RESULTS

The mean age of the participants (n = 269) was 33 years, 62% were women, and AM among HIV+ and HIV- was similar (36% versus 37%). NCI was found in 23% (62/269) of participants. HIV+/AM+ had a higher prevalence of impaired learning and executive functions and were more depressed than HIV-/AM- or HIV+/AM-. HIV+ with CD4 T-cell counts ≤200/µL were more impaired in the learning domain than those with >200/µL. HIV+/AM+ group had higher levels of sCD14 compared to the other 3 groups and higher levels of sCD163 than the HIV-/AM- group. Higher levels of sCD14 and sCD163 were each associated with NCI. The sCD163 (log10) levels were higher for those with 1+ versus 2+ parasitemia level.

CONCLUSIONS

HIV and AM coinfection was associated with an increased risk of reduced learning and executive functions, and elevated systemic inflammation. Mood was more depressed in HIV patients with than those without AM. The mechanisms and long-term effects on neurocognition and depression among HIV+/AM+ individuals should be studied because this coinfection is common globally.

An observational study identifying highly tuberculosis-exposed, HIV-1-positive but persistently TB, tuberculin and IGRA negative persons with M. tuberculosis specific antibodies in Cape Town, South Africa

Background

Mycobacterium tuberculosis (Mtb) infection is inferred from positive results of T-cell immune conversion assays measuring Mtb-specific interferon gamma production or tuberculin skin test (TST) reactivity. Certain exposed individuals do not display T-cell immune conversion in these assays and do not develop TB. Here we report a hitherto unknown form of this phenotype: HIV-1-positive persistently TB, tuberculin and IGRA negative (HITTIN).

Methods

A community-based case-control design was used to systematically screen and identify adults living with HIV (HIV+), aged 35–60 years, who met stringent study criteria, and then longitudinally followed up for repeat IGRA and TST testing. Participants had no history of TB despite living in TB hyper-endemic environments in Cape Town, South Africa with a provincial incidence of 681/100,000. Mtb-specific antibodies were measured using ELISA and Luminex.

Findings

We identified 48/286 (17%) individuals who tested persistently negative for Mtb-specific T-cell immunoreactivity (three negative Quantiferon results and one TST = 0mm) over 206±154 days on average. Of these, 97·2% had documented CD4 counts<200 prior to antiretroviral therapy (ART). They had received ART for 7·0±3·0 years with a latest CD4 count of 505·8±191·4 cells/mm³. All HITTIN sent for further antibody testing (n=38) displayed  Mtb-specific antibody titres.

Interpretation

Immune reconstituted HIV+ persons can be persistently non-immunoreactive to TST and interferon-γ T-cell responses to Mtb, yet develop species-specific antibody responses. Exposure is evidenced by Mtb-specific antibody titres. Our identification of HIV+ individuals displaying a persisting lack of response to TST and IGRA T-cell immune conversion paves the way for future studies to investigate this phenotype in the context of HIV-infection that so far have received only scant attention.

Characteristics Indicative of Tuberculosis/HIV Coinfection in a High-Burden Setting: Lessons from 13,802 Incident Tuberculosis Cases in Harare, Zimbabwe

Country-specific interventions targeting high-risk groups are necessary for a global reduction in Tuberculosis (TB)/HIV burden. We analyzed the data of 13,802 TB cases diagnosed in Harare, Zimbabwe, during 2013-2017. Pearson's chi-square tests and multivariate logistic regression models were used to identify patient characteristics significantly associated with TB/HIV coinfection. Of the 13,802 TB cases analyzed, 9,725 (70.5%) were HIV positive. A significantly higher odds of having TB/HIV coinfection diagnosis was found among females, patients aged 25-64 years, previously treated cases, and acid-fast bacillus sputum smear-negative cases. Compared with nondisseminated pulmonary TB, miliary TB (adjusted odds ratio [aOR]: 1.469, 95% CI: 1.071, 2.015) and TB meningitis (aOR: 1.715, 95% CI: 1.074, 2.736) both had a significantly higher odds for TB/HIV coinfection, whereas pleural TB (aOR 0.420, 95% CI: 0.354, 0.497) and all other extrapulmonary TB (EPTB) (aOR: 0.606, 95% CI: 0.516 0.712) were significantly less likely to have TB/HIV coinfection. The risk for TB/HIV coinfection varied significantly by patients' sociodemographic and clinical characteristics in Harare. Our finding that different forms of EPTB have different relationships with HIV coinfection has extended the knowledge base about clinical markers for TB/HIV coinfection which can lead to a greater public health impact on eliminating TB/HIV infection.

Small Animal Model of Post-chemotherapy Tuberculosis Relapse in the Setting of HIV Co-infection

Tuberculosis relapse following drug treatment of active disease is an important global public health problem due to the poorer clinical outcomes and increased risk of drug resistance development. Concurrent infection with HIV, including in those receiving anti-retroviral therapy (ART), is an important risk factor for relapse and expansion of drug resistant Mycobacterium tuberculosis (Mtb) isolates. A greater understanding of the HIV-associated factors driving TB relapse is important for development of interventions that support immune containment and complement drug therapy. We employed the humanized mouse to develop a new model of post-chemotherapy TB relapse in the setting of HIV infection. Paucibacillary TB infection was observed following treatment with Rifampin and Isoniazid and subsequent infection with HIV-1 was associated with increased Mtb burden in the post-drug phase. Organized granulomas were observed during development of acute TB and appeared to resolve following TB drug therapy. At relapse, granulomatous pathology in the lung was infrequent and mycobacteria were most often observed in the interstitium and at sites of diffuse inflammation. Compared to animals with HIV mono-infection, higher viral replication was observed in the lung and liver, but not in the periphery, of animals with post-drug TB relapse. The results demonstrate a potential role for the humanized mouse as an experimental model of TB relapse in the setting of HIV. Long term, the model could facilitate discovery of disease mechanisms and development of clinical interventions.

HIV-TB co-infection with clinical presentation, diagnosis, treatment, outcome and its relation to CD4 count, a cross-sectional study in a tertiary care hospital in coastal Karnataka

Introduction

Tuberculosis (TB) is the leading killer and the commonest opportunistic infection (OI) in human immunodeficiency virus (HIV) infected individuals with 0.3 million deaths in 2017. When HIV and TB co-infection occurs, they form a deadly combination with each accelerating the progression of the other, resulting in increased morbidity and mortality.

Aim and Objectives

To study the demographic pattern, clinical presentation, opportunistic infections, radiological and laboratory profile, management, and outcome of HIV-TB coinfected individuals.

Materials and Methods

A prospective cross-sectional study was carried out on confirmed HIV cases already diagnosed with TB and those newly detected with TB after admission, where diagnosis was carried out following standard operative procedures.

Results

In our study of 58 HIV-TB co-infected individuals, 40-50 years was the most common age group affected. Males were affected more with majority being married. The most common presentation was fever (67%) followed by gastrointestinal symptoms. Majority of TB cases were newly diagnosed (65.5%), with predominance of pulmonary tuberculosis (PTB) (n = 35) followed by those having only extrapulmonary tuberculosis (EPTB) (n = 12) and both (n = 11). TB was diagnosed by microscopy in 32.7%, while radiologically, chest X-ray was most common (36.2%). Also, 50% were infected with other OIs where oral candidiasis was the most common (37.93%). The overall mean CD4 count was 220 cells/μL and those with EPTB had lesser CD4 counts than those with PTB. All were on DOTS regimen and majority showed improvement.

Conclusion

In a country like India where both these diseases are rampant, we recommend better information, education, understanding and awareness for prevention, care, early diagnosis, and treatment of these two notorious infectious diseases with prevention of relapse and default of TB cases in HIV-TB co-infected individuals a priority.

Role Of Vitamin-D Supplementation In TB/HIV Co-Infected Patients

OBJECTIVE

This review aimed to assess the role of vitamin D supplementation on the decrement of mortality and morbidity rate among tuberculosis (TB)/human immune deficiency virus (HIV) co-infected clients.Method: Pub Med, google scholar and google search were accessed to find out all document to describe this review article.

RESULTS

Nowadays TB/HIV co-infection has become a major global concern, particularly in low and middle-income countries. Mycobacterium tuberculosis and HIV infections are co-endemic and more susceptible to the progression of TB. Immunosuppression associated with HIV is a strong risk factor for the reactivation of latent TB to the active form. Immune cells like macrophages recognized Mycobacterium tuberculosis through TLR2/1, and it increases the expression of the vitamin D receptor (VDR) and CYP27B1. The synthesis of 1,25-dihydroxy vitamin D promotes VDR-mediated transactivation of the antimicrobial peptide cathelicidin and the killing of intracellular Mycobacterium tuberculosis. Cathelicidins have a direct antimicrobial effect through membrane disruption. Besides, it has also antiviral effects via inhibition of retrovirus (HIV) replication. In fact, as some studies showed, there was a lower induction of cathelicidin in monocytes who have low vitamin D levels.Conclusion: Therefore, vitamin D supplementation can be directly involved in the reduction of TB/HIV co-infection and its progression.

Incidence of tuberculosis among HIV infected individuals on long term antiretroviral therapy in private healthcare sector in Pune, Western India

Background

Despite rapid scale up of antiretroviral therapy (ART), Tuberculosis (TB) remains the commonest opportunistic infection and cause of death among HIV infected individuals in resource limited settings like India. Incidence of TB in individuals on ART in private healthcare sector in India is infrequently studied.

Methods

This retrospective cohort study conducted between 1st March 2009 and 1st March 2017 aimed to evaluate rate of incident TB in individuals initiated on ART at 3 private sector ART clinics in Pune, India. Individuals more than 12 years of age with ART duration of atleast 6 months were included. Patients were classified as having prevalent TB if they had a TB episode within the year prior to ART initiation or if they developed TB within 6 months of starting ART. Individuals who were diagnosed with TB after 6 months of starting ART were classified as incident TB cases. A recurrent episode of TB after treatment completion or cure of prevalent TB was also regarded as incident TB. Patients were classified as definitive TB if Mycobacterium tuberculosis was grown in culture from a biological sample or a positive rapid molecular test. Patients were classified as probable TB if there was radiologic evidence of TB in absence of confirmatory culture or PCR.

Results

1904 patients with a median duration of follow up on ART of 57 (IQR = 32.0, 84.0) months were included. Of these, 182 developed incident TB (22% definitive TB, 38% recurrent cases). TB incidence at 6–12 months, 13–24 months, 25–60 months and > 60 months of ART was 24.32, 5.46, 2.54 and 0.75 cases per 100 person years respectively. Current time updated CD4 count < 500 cells/mm³ (p < 0.0001), virologic failure on ART (adjusted Hazard Ratio (aHR): 3.05 (95% CI: 2.094, 4.454), p < 0.0001) and receipt of ART without IPT (aHR: 8.24 (95% CI, 3.358, 20.204), p < 0.0001) were associated with higher risk of incident TB.

Conclusion

Starting ART early in treatment naïve individuals, prompt detection of virologic failure on ART and providing IPT along with ART will be useful in reducing incident TB. Efforts from private sector are crucial in achieving Sustainable Development Goals set by Government of India and attaining the vision of a TB free India.

Mycobacterium tuberculosis Beijing genotype strains and unfavourable treatment outcomes: a systematic review and meta-analysis

OBJECTIVES

The Mycobacterium tuberculosis Beijing genotype was first described in 1995 and is now the predominant strain among patients with tuberculosis in many Asian countries. The rapid global spread of the Beijing genotype is receiving increasing attention because it can cause a higher risk of treatment failures. Our objective was to assess the association between the Beijing genotype and unfavourable treatment outcomes of tuberculosis.

METHODS

We searched for eligible studies through PubMed, Web of Science, Chinese National Knowledge Infrastructure and Wanfang Data. We included cohort studies that evaluated treatment outcomes and Beijing genotype strains. Participants were individuals with active pulmonary tuberculosis. The association between Beijing genotype and the risk of unfavourable treatment outcomes was assessed using the pooled odds ratios (ORs) with corresponding confidence intervals (CIs).

RESULTS

In total, 7489 tuberculosis patients were involved in the analysis. Patients infected with the Beijing genotype were more likely to have unfavourable treatment outcomes, with the OR of 2.04 (95% CI 1.52-2.75). The pooled OR was 2.33 (95% CI 1.71-3.16) for recurrence, 2.36 (95% CI 1.69-3.30) for relapse and 2.62 (95% CI 1.90-3.61) for treatment failure, respectively. Subgroup analysis revealed that Beijing genotype was a significant risk factor for unfavourable treatment outcomes in Asians (OR 2.28, 95% CI 1.82-2.86) or in drug-susceptible TB patients (OR 2.11, 95% CI 1.31-3.39). No significant association was observed among non-Asian populations (OR 1.17, 95% CI 0.73-1.86) or patients with multidrug-resistant (MDR) tuberculosis (OR 0.97, 95% CI 0.48-1.94).

CONCLUSIONS

Our results suggest that Mycobacterium tuberculosis Beijing genotype is associated with an increased risk of unfavourable treatment outcomes, including treatment failure and relapse.

Whole genome sequencing provides additional insights into recurrent tuberculosis classified as endogenous reactivation by IS6110 DNA fingerprinting

Recurrent tuberculosis (TB) after successful TB treatment occurs due to endogenous reactivation (relapse) or exogenous reinfection. We revisited the conclusions of relapse in a high TB incidence setting that were drawn on the basis of IS6110 restriction fragment length polymorphism (RFLP) analysis in a large retrospective cohort study in suburban Cape Town, South Africa. Using whole genome sequencing (WGS), we undertook pair-wise genome comparison of Mycobacterium tuberculosis strains cultured from diagnostic sputum samples collected at the index and recurrent TB episode for 25 recurrent TB cases who had been classified as relapse based on identical DNA fingerprint patterns in the earlier study. We found that paired strain genome sequences were identical or showed minimal variant differences in 22 of 25 recurrent TB cases, consistent with relapse. One showed 20 variant differences, suggestive of exogenous reinfection. Two of the 25 had mixed infections, each with the index episode strain detected as the dominant strain at recurrence in one of these patients, the minority strain harboured drug-resistance conferring mutations (rpoB, katG). In conclusion, our study highlights the additional value of WGS for investigating recurrent TB in settings with high infection pressure and closely related circulating strains, where the extent of re- and mixed infection may be underestimated.

Novel therapeutic approaches for targeting TB and HIV reservoirs prevailing in lungs

INTRODUCTION

Coinfection with Mycobacterium tuberculosis is the leading cause of death in HIV positive patients. In 2017, about 0.3 million HIV positive people died of tuberculosis. There is high load of mycobacteria and HIV in the lungs and eradication of the same is vital for patient survival.

AREAS COVERED

This review focuses on the pathogenesis of HIV-TB coinfection and the current management approaches of this coinfection. It presents a detailed discussion of current investigations in novel drug delivery systems for effective targeting of HIV-TB lung reservoirs, especially via pulmonary drug delivery. Additionally, emphasis is given to the need of HIV-TB cotargeting, an unmet need in management of HIV-TB coinfection.

EXPERT OPINION

To achieve the goal of complete eradication of HIV-TB reservoirs in lungs requires focused research strategies to be undertaken in the area of pulmonary delivery systems. These endeavors could eventually lead to better patient compliance and improved treatment outcomes. The treatment regimen of HIV-TB coinfection is associated with a major drawback of low therapeutic concentration of drugs in lungs. Nanotechnology provides an excellent platform for delivery of anti-TB and anti-HIV drugs via the pulmonary route thereby serving as a viable and effective means of managing the mycobacterial and HIV reservoirs in the lungs.

Infection of multiple Mycobacterium tuberculosis strains among tuberculosis/human immunodeficiency virus co-infected patients: A molecular study in Myanmar

Background:

Appearance of Mycobacterium tuberculosis (MTB) in the sputum of a tuberculosis (TB)/human immunodeficiency virus (HIV) co-infected patient under treatment may indicate either failure or new infection. This study aims to evaluate whether TB treatment failure among TB/HIV co-infected patients is a real failure.

Methods:

A prospective cohort study was conducted among 566 TB/HIV co-infected patients who started TB treatment in 12 townships in the upper Myanmar. Among the 566 participants, 16 (2.8%) resulted in treatment failure. We performed a molecular study using mycobacterial interspersed repetitive-unit-variable number of tandem repeat (MIRU-VNTR) genotyping for them. The MIRU-VNTR profiles were analyzed using the web server, MIRU-VNTRplus. All data were entered into EpiData version 3.1 and analyzed using R version 3.4.3.

Results:

Among 16 failure patients, seven had incomplete laboratory results. Of the nine remaining patients, nobody had exactly the same MIRU-VNTR pattern between the initial and final isolates. Four patients had persistent East-African Indian (EAI) lineages and one each had persistent Beijing lineage, changing from EAI to Beijing, from Beijing to EAI, NEW-1 to Beijing, and NEW-1 to X strains. Female patients have significantly larger genetic difference between MTB of the paired isolates than male patients (t-test, P = 0.04).

Conclusion:

Thus, in our study patients, infection of multiple MTB strains is a possible cause of TB treatment failure. Explanation for the association between gender and distance of genotypes from the initial to subsequent MTB infection needs further studies.

Advances in the understanding of Mycobacterium tuberculosis transmission in HIV-endemic settings

Tuberculosis claims more human lives than any other infectious disease. This alarming epidemic has fuelled the development of novel antimicrobials and diagnostics. However, public health interventions that interrupt transmission have been slow to emerge, particularly in HIV-endemic settings. Transmission of tuberculosis is complex, involving various environmental, bacteriological, and host factors, among which concomitant HIV infection is important. Preventing person-to-person spread is central to halting the epidemic and, consequently, tuberculosis transmission is now being studied with renewed interest. In this Series paper, we review recent advances in the understanding of tuberculosis transmission, from the view of source-case infectiousness, inherent susceptibility of exposed individuals, appending tools for predicting risk of disease progression, the biophysical nature of the contagion, and the environments in which transmission occurs and is sustained in populations. We focus specifically on how HIV infection affects these features with a view to describing novel transmission blocking strategies in HIV-endemic settings.

BIOIMPEDANCE MARKERS AND TUBERCULOSIS OUTCOME AMONG HIV-INFECTED PATIENTS

Background

The changes in body composition markers (weight, fat mass, lean mass, and BMI) over time can be associated with TB treatment outcome among HIV-infected patients. The aim of this study was to investigate whether changes in fat mass and lean mass were associated with the treatment response among patients with HIV infection and pulmonary tuberculosis.

Materials and Methods

This was a prospective cohort study. Data from HIV-infected patients commencing TB therapy were analyzed. This included body weight measurement using bioimpedance equipment at baseline, one month, and two months after starting TB treatment.

Results

The study was conducted in 125 patients, 17 patients (13.6%) died during treatment, of which 5 died during the first month of treatment, 4 during the second month and 8 after the second month. The group of patients with good response, increased their weight by 1.3 kg (p <0.001) at the end of the first month of TB treatment and 2.6 kg in the second month (p <0.001), and body fat increase was 1.2 Kg (p <0.001) and 2.3 kg (p <0.001), the first and second month respectively. The group of patients who died had lost 2.1 kg fat mass after the first month (p <0.001) and 3.7 kg in the second month (p <0.001).

Conclusions

Our results show that the weight change during TB treatment (increased fat mass) helps us predict therapeutic response. Weight loss during the first month of starting therapy should be evaluated thoroughly to identify the probable cause of treatment failure.

Recurrence of tuberculosis in a low-incidence setting: a retrospective cross-sectional study augmented by whole genome sequencing

Background

The recurrence of tuberculosis (TB) disease in treated patients can serve as a marker of the efficacy of TB control programs. Recurrent disease represents either endogenous reactivation with the same strain of Mycobacterium tuberculosis due to non-compliance or inadequate therapy or exogenous reinfection with a new strain. Genotyping or whole genome sequencing (WGS) of M. tuberculosis isolates from initial and recurrent cases can differentiate between reinfection and reactivation. This study examined cases of recurrent TB in New South Wales, Australia, using genotyping and WGS.

Methods

Culture-confirmed TB cases diagnosed at least 12 months apart between January 2011 and December 2016 were included. Isolates of M. tuberculosis from patients were compared using 24-locus Mycobacterial Interspersed Repetitive Unit Variable Number Tandem Repeat (MIRU-24) typing and WGS.

Results

Eighteen cases of recurrent disease were identified but isolates from only 15 (83%) were available for study. MIRU-24 findings classified 13 (13/15; 87%) as reactivation and two (13%), as reinfection. Sequencing 13 cultivable paired isolates demonstrated 11 reactivations and two reinfections. There was genomic similarity in 10 out of 13 pairs while one case (1/13; 8%) had 12 SNPS differences. Two other cases (2/13;15%) had > 200 SNPs differences and were classified as reinfection. No phenotypic or genomic evidence of drug resistance was observed.

Conclusion

TB control programs can achieve consistently low rates of recurrent disease in low incidence settings. WGS of implicated isolates augments the differentiation between reactivation and reinfection and indicates that the majority of recurrences are due to reactivation rather than reinfection. Predominance of reactivation over reinfection indicates high-quality public health practices and a low risk of local transmission.

Trial registration

This study was approved by the Western Sydney Local Health District (WSLHD) Human Research Ethics Committee (HREC Ref: AU RED LNR/17/WMEAD/190; SSA Ref: LNR SSA/17/WMEAD/191).

23-valent pneumococcal polysaccharide vaccine elicits hierarchical antibody and cellular responses in healthy and tuberculosis-cured elderly, and HIV-1-infected subjects

The PPV23 immunizes healthy elderly and other high-risk populations against pneumococcal disease. Immune mechanisms whereby these populations differently mount antibody(Ab) and cellular responses to PPV23 vaccination remain unknown. Here, healthy elderly, those elderly with prior tuberculosis-cured history (TB-cured), and HIV-infected humans were vaccinated with PPV23, and assessed for opsonophagocytic Ab responses and potential cellular mechanisms. PPV23 vaccination elicited hierarchical responses of opsonophagocytic Ab. PPV23-elicited Ab titers were highest in healthy elderly, significantly lower in TB-cured elderly and lowest in HIV-infected subjects. Mechanistically, high PPV23-elicited Ab titers in healthy elderly were associated with increases in CD19 + CD69+ cells and CD19 + CD138 + plasma cells. Surprisingly, TB-cured elderly failed to show PPV23-induced increases in these cells. While HIV-infected subjects showed a depressed CD19 + CD69+ cellular response, PPV23 vaccination uncovered HIV-related over-reactive increases in CD19 + CD138 + cells. For the first time, we demonstrate that PPV23-elicted opsonophagocytic Ab titers correlate with different cellular responses in healthy, TB-cured and HIV statuses.

Tuberculosis along the continuum of HIV care in a cohort of adolescents living with HIV in Ethiopia

SETTING

Eight health facilities in Ethiopia.

OBJECTIVE

To determine tuberculosis (TB) incidence rates and associated factors among adolescents living with the human immunodeficiency virus (ALHIV).

DESIGN

This was a retrospective cohort study. Adolescents enrolled in HIV care between January 2005 and 31 December 2013 constituted the study population. The main outcome variable was TB diagnosis during follow-up. Baseline World Health Organization (WHO) clinical stage, CD4 count, previous history of TB and use of isoniazid preventive therapy (IPT) were the main independent variables. We estimated TB incidence rates as incident cases per 100 person-years of observation (PYO). Cox regression analysis was used to control for confounders.

RESULTS

Of the 1221 adolescents screened, 1072 were studied; 60.1% were girls. TB incidence rate was 16.32 per 100 PYO during pre-antiretroviral therapy (pre-ART) follow-up but declined to 2.25 per 100 PYO after initiation of ART. Advanced WHO clinical stage (adjusted hazard ratio [aHR] 2.71, 95%CI 1.69-4.33) and CD4 count <350 cells/μl (aHR 2.28, 95%CI 1.10-4.81) predicted TB incidence in the pre-ART cohort. IPT use was associated with a significant reduction in TB incidence in the ART cohort, but not in the pre-ART group.

CONCLUSION

Although TB was a significant problem in ALHIV, timely administration of ART and IPT had a significant protective effect.

The Immune Interaction between HIV-1 Infection and Mycobacterium tuberculosis

The modulation of tuberculosis (TB)-induced immunopathology caused by human immunodeficiency virus (HIV)-1 coinfection remains incompletely understood but underlies the change seen in the natural history, presentation, and prognosis of TB in such patients. The deleterious combination of these two pathogens has been dubbed a "deadly syndemic," with each favoring the replication of the other and thereby contributing to accelerated disease morbidity and mortality. HIV-1 is the best-recognized risk factor for the development of active TB and accounts for 13% of cases globally. The advent of combination antiretroviral therapy (ART) has considerably mitigated this risk. Rapid roll-out of ART globally and the recent recommendation by the World Health Organization (WHO) to initiate ART for everyone living with HIV at any CD4 cell count should lead to further reductions in HIV-1-associated TB incidence because susceptibility to TB is inversely proportional to CD4 count. However, it is important to note that even after successful ART, patients with HIV-1 are still at increased risk for TB. Indeed, in settings of high TB incidence, the occurrence of TB often remains the first presentation of, and thereby the entry into, HIV care. As advantageous as ART-induced immune recovery is, it may also give rise to immunopathology, especially in the lower-CD4-count strata in the form of the immune reconstitution inflammatory syndrome. TB-immune reconstitution inflammatory syndrome will continue to impact the HIV-TB syndemic.

HIV and mycobacteria

The importance of mycobacteria as opportunistic pathogens, particularly members of the M. avium complex (MAC), in patients with progressive HIV infection was recognized early in the AIDS epidemic. It took longer to appreciate the global impact and devastation that would result from the deadly synergy that exists between HIV and M. tuberculosis. This HIV/M. tuberculosis co-pandemic is ongoing and claiming millions of lives every year. In addition to MAC, a number of other non-tuberculous mycobacteria have been recognized as opportunistic pathogens in HIV-infected individuals; some of these are more commonly encountered (e.g., M. kansasii) than others (M. haemophilum and M. genevense). Finally, there are challenges to concomitantly treating the HIV and the infecting Mycobacterium species, because of antimicrobial resistance, therapeutic side-effects and the complex pharmacologic interactions of the antiretroviral and antimycobacterial multidrug therapy.

Recurrent tuberculosis in an urban area in China: Relapse or exogenous reinfection?

Recurrent tuberculosis is an important indicator of the effectiveness of tuberculosis control and can occur by relapse or exogenous reinfection. We conducted a retrospective cohort study on all bacteriologically confirmed tuberculosis cases that were successfully treated between 2000 and 2012 in Shanghai, an urban area with a high number but a low prevalence rate of tuberculosis cases and a low prevalence of HIV infection. Genotyping the Mycobacterium tuberculosis from clinical isolates was used to distinguish between relapse and reinfection. In total, 5.3% (710/13,417) of successfully treated cases had a recurrence, a rate of 7.55 (95% CI 7.01-8.13) episodes per 1000 person-years, more than 18 times the rate of tuberculosis in the general population. Patients who were male, age 30-59, retreatment cases, had cavitation, diabetes, drug-resistant or multidrug-resistant tuberculosis in their initial episode of tuberculosis, were at high risk for a recurrence. Among 141 recurrent cases that had paired isolates, 59 (41.8%) had different genotypes, indicating reinfection with a different strain. Patients who completed treatment were still at high risk of another episode of tuberculosis and exogenous reinfection contributed a significant proportion of the recurrent tuberculosis cases. Targeted control strategies are needed to prevent new tuberculosis infections in this setting.

Metabolic Perspectives on Persistence

Accumulating evidence has left little doubt about the importance of persistence or metabolism in the biology and chemotherapy of tuberculosis. However, knowledge of the intersection between these two factors has only recently begun to emerge. Here, we provide a focused review of metabolic characteristics associated with Mycobacterium tuberculosis persistence. We focus on metabolism because it is the biochemical foundation of all physiologic processes and a distinguishing hallmark of M. tuberculosis physiology and pathogenicity. In addition, it serves as the chemical interface between host and pathogen. Existing knowledge, however, derives largely from physiologic contexts in which replication is the primary biochemical objective. The goal of this review is to reframe current knowledge of M. tuberculosis metabolism in the context of persistence, where quiescence is often a key distinguishing characteristic. Such a perspective may help ongoing efforts to develop more efficient cures and inform on novel strategies to break the cycle of transmission sustaining the pandemic.

Tuberculosis cases caused by heterogeneous infection in Eastern Europe and their influence on outcomes

INTRODUCTION

Mycobacterium tuberculosis superinfection is known to occur in areas with high rates of tuberculosis (TB) and has a significant impact on overall clinical TB management.

AIM

We aimed to estimate the superinfection rate in cohorts of drug sensitive and multi-drug resistant tuberculosis (MDR TB) patients from Eastern Europe and the potential role of a second MDR TB strain infecting a patient with active non-MDR TB in treatment outcome.

METHODS

The study population included 512 serial M. tuberculosis isolates obtained from 84 MDR- and 136 non-MDR TB patients recruited sequentially at sites in Lithuania, Latvia and Russia in 2011-2013. Strains were genotyped using standardized 24-loci Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeat (MIRU-VNTR) typing.

RESULTS

Changes in two or more MIRU-VNTR loci suggesting superinfection were detected in 13 patients (5.9%). We found 4 initially non-MDR TB patients superinfected with an MDR TB strain during treatment and 3 of them had an unsuccessful outcome.

CONCLUSIONS

An unsuccessful treatment outcome in patients initially diagnosed with drug sensitive TB might be explained by superinfection with an MDR TB strain. Bacteriological reversion could be indicative of superinfection with another strain. Archiving of all serial isolates and their genotyping in case of culture reversion could support therapeutic strategies in high MDR TB burden settings if resources are available.

Tuberculosis, before and after Antiretroviral Therapy among HIV-Infected Children in Nigeria: What Are the Risk Factors?

INTRODUCTION

In Nigeria, there is a dearth of pediatric data on the risk factors associated with tuberculosis (TB), before and after antiretroviral therapy (ART).

METHODOLOGY

A retrospective observational cohort study, between October 2010 and December 2013, at the Federal Medical Centre, Makurdi, Nigeria. TB was noted among children less than 15 years of age at ART enrolment (prevalent TB-PrevTB), within 6 months (early incident tuberculosis-EITB) and after 6 months (late incident tuberculosis-LITB) of a 12-month follow-up on ART. Potential risk factors for PrevTB and incident TB were assessed using the multivariate logistic and Cox regression models respectively.

RESULTS

Among 368 HIV-1 infected children, PrevTB was diagnosed in 73 children (19.8%). Twenty-eight EITB cases were diagnosed among 278 children over 132 person-years (py) with an EITB rate of 21.2/100 py. Twelve LITB cases were seen among 224 children over 221.9 py with a LITB rate of 5.4/100 py. A significant reduction in the incidence rates of TB was found over time (75%, p˂ 0.001). Young age of children (12-35 months, aOR; 24, 95% CI; 4.1-146.6, p ˂ 0.001; 36-59 months, aOR;21, 95%CI;4.0-114.3, p ˂ 0.001); history of TB in children (aOR; 29, 95% CI; 7.3-119.4, P˂ 0.001); severe immunosuppression (aOR;38, 95% CI;12-123.2,p ˂ 0.001); oropharyngeal candidiasis (aOR;3.3, 95% CI; 1.4-8.0, p = 0.009) and sepsis (aOR; 3.2, 95% CI;1.0-9.6, p = 0.043) increased the risk of PrevTB. Urban residency was protective against EITB (aHR; 0.1, 95% CI; 0.0-0.4, p = 0.001). Virological failure (aHR; 4.7, 95% CI; 1.3-16.5, p ˂ 0.001) and sepsis (aHR; 26, 95% CI; 5.3-131.9, p ˂ 0.001) increased the risk of LITB.

CONCLUSIONS

In our cohort of HIV-infected children, a significant reduction in cases of incident TB was seen following a 12-month use of ART. After ART initiation, TB screening should be optimized among children of rural residency, children with sepsis, and those with poor virological response to ART.

The timing of tuberculosis after isoniazid preventive therapy among gold miners in South Africa: a prospective cohort study

BACKGROUND

The durability of isoniazid preventive therapy (IPT) in preventing tuberculosis (TB) is limited in high-prevalence settings. The underlying mechanism (reactivation of persistent latent TB or reinfection) is not known. We aimed to investigate the timing of TB incidence during and after IPT and associated risk factors in a very high TB and HIV-prevalence setting, and to compare the observed rate with a modelled estimate of TB incidence rate after IPT due to reinfection.

METHODS

In a post-hoc analysis of a cluster-randomized trial of community-wide IPT among South African gold miners, all intervention arm participants that were dispensed IPT for at least one of the intended 9 months were included. An incident TB case was defined as any participant with a positive sputum smear or culture, or with a clinical TB diagnosis assigned by a senior study clinician. Crude TB incidence rates were calculated during and after IPT, overall and by follow-up time. HIV status was not available. Multivariable Cox regression was used to analyse risk factors by follow-up time after IPT. Estimates from a published mathematical model of trial data were used to calculate the average reinfection TB incidence in the first year after IPT.

RESULTS

Among 18,520 participants (96% male, mean age 41 years, median follow-up 2.1 years), 708 developed TB. The TB incidence rate during the intended IPT period was 1.3/100 person-years (pyrs; 95% confidence interval (CI), 1.0-1.6) and afterwards 2.3/100 pyrs (95% CI, 1.9-2.7). TB incidence increased within 6 months followed by a stable rate over time. There was no evidence for changing risk factors for TB disease over time after miners stopped IPT. The average TB incidence rate attributable to reinfection in the first year was estimated at 1.3/100 pyrs, compared to an observed rate of 2.2/100 pyrs (95% CI, 1.8-2.7).

CONCLUSIONS

The durability of protection by IPT was lost within 6-12 months in this setting with a high HIV prevalence and a high annual risk of M. tuberculosis infection. The observed rate was higher than the modelled rate, suggesting that reactivation of persistent latent infection played a role in the rapid return to baseline TB incidence.

Tuberculosis

Although the worldwide incidence of tuberculosis has been slowly decreasing, the global disease burden remains substantial (∼9 million cases and ∼1·5 million deaths in 2013), and tuberculosis incidence and drug resistance are rising in some parts of the world such as Africa. The modest gains achieved thus far are threatened by high prevalence of HIV, persisting global poverty, and emergence of highly drug-resistant forms of tuberculosis. Tuberculosis is also a major problem in health-care workers in both low-burden and high-burden settings. Although the ideal preventive agent, an effective vaccine, is still some time away, several new diagnostic technologies have emerged, and two new tuberculosis drugs have been licensed after almost 50 years of no tuberculosis drugs being registered. Efforts towards an effective vaccine have been thwarted by poor understanding of what constitutes protective immunity. Although new interventions and investment in control programmes will enable control, eradication will only be possible through substantial reductions in poverty and overcrowding, political will and stability, and containing co-drivers of tuberculosis, such as HIV, smoking, and diabetes.

Pulmonary Tuberculosis in Humanized Mice Infected with HIV-1

Co-infection with HIV increases the morbidity and mortality associated with tuberculosis due to multiple factors including a poorly understood microbial synergy. We developed a novel small animal model of co-infection in the humanized mouse to investigate how HIV infection disrupts pulmonary containment of Mtb. Following dual infection, HIV-infected cells were localized to sites of Mtb-driven inflammation and mycobacterial replication in the lung. Consistent with disease in human subjects, we observed increased mycobacterial burden, loss of granuloma structure, and increased progression of TB disease, due to HIV co-infection. Importantly, we observed an HIV-dependent pro-inflammatory cytokine signature (IL-1β, IL-6, TNFα, and IL-8), neutrophil accumulation, and greater lung pathology in the Mtb-co-infected lung. These results suggest that in the early stages of acute co-infection in the humanized mouse, infection with HIV exacerbates the pro-inflammatory response to pulmonary Mtb, leading to poorly formed granulomas, more severe lung pathology, and increased mycobacterial burden and dissemination.

A systematic review of published literature describing factors associated with tuberculosis recurrence in people living with HIV in Africa

BACKGROUND

A summary of factors associated with recurrent tuberculosis (TB) in the African HIV-infected population is lacking. We performed a systematic review to address this.

METHODS

We performed a literature search within PubMed and The WHO Global Library with specific inclusion and exclusion criteria to identify manuscripts emanating from the African continent which potentially described factors associated with recurrent TB in persons living with HIV.

RESULTS

The literature search yielded 52 unique manuscripts, of which only 4 manuscripts were included in the final systematic review following application of the inclusion and exclusion criteria. Baseline CD4 count, baseline HIV viral load, a positive tuberculin skin test, prior active TB disease, cutaneous hypersensitivity reaction to treatment, having < 3 lung zones affected by prior TB disease, and anaemia were associated with recurrent TB in HIV-infected individuals, whilst age and antiretroviral status were not.

CONCLUSION

The lack of studies describing recurrent TB in Africa which stratify results by HIV-status is a hindrance to understanding risk factors for recurrent TB in this population. This might be overcome by implementing guidelines related to the publishing of data from observational studies in peer-reviewed medical journals reporting recurrent TB in populations with a high-burden of HIV infection.

T cells and adaptive immunity to Mycobacterium tuberculosis in humans

The adaptive immune response mediated by T cells is critical for control of Mycobacterium tuberculosis (M. tuberculosis) infection in humans. However, the M. tuberculosis antigens and host T-cell responses that are required for an effective adaptive immune response to M. tuberculosis infection are yet to be defined. Here, we review recent findings on CD4(+) and CD8(+) T-cell responses to M. tuberculosis infection and examine the roles of distinct M. tuberculosis-specific T-cell subsets in control of de novo and latent M. tuberculosis infection, and in the evolution of T-cell immunity to M. tuberculosis in response to tuberculosis treatment. In addition, we discuss recent studies that elucidate aspects of M. tuberculosis-specific adaptive immunity during human immunodeficiency virus co-infection and summarize recent findings from vaccine trials that provide insight into effective adaptive immune responses to M. tuberculosis infection.

Pharmacodynamic Modeling of Bacillary Elimination Rates and Detection of Bacterial Lipid Bodies in Sputum to Predict and Understand Outcomes in Treatment of Pulmonary Tuberculosis

BACKGROUND

Antibiotic-tolerant bacterial persistence prevents treatment shortening in drug-susceptible tuberculosis, and accumulation of intracellular lipid bodies has been proposed to identify a persister phenotype of Mycobacterium tuberculosis cells. In Malawi, we modeled bacillary elimination rates (BERs) from sputum cultures and calculated the percentage of lipid body-positive acid-fast bacilli (%LB + AFB) on sputum smears. We assessed whether these putative measurements of persistence predict unfavorable outcomes (treatment failure/relapse).

METHODS

Adults with pulmonary tuberculosis received standard 6-month therapy. Sputum samples were collected during the first 8 weeks for serial sputum colony counting (SSCC) on agar and time-to positivity (TTP) measurement in mycobacterial growth indicator tubes. BERs were extracted from nonlinear and linear mixed-effects models, respectively, fitted to these datasets. The %LB + AFB counts were assessed by fluorescence microscopy. Patients were followed until 1 year posttreatment. Individual BERs and %LB + AFB counts were related to final outcomes.

RESULTS

One hundred and thirty-three patients (56% HIV coinfected) participated, and 15 unfavorable outcomes were reported. These were inversely associated with faster sterilization phase bacillary elimination from the SSCC model (odds ratio [OR], 0.39; 95% confidence interval [CI], .22-.70) and a faster BER from the TTP model (OR, 0.71; 95% CI, .55-.94). Higher %LB + AFB counts on day 21-28 were recorded in patients who suffered unfavorable final outcomes compared with those who achieved stable cure (P = .008).

CONCLUSIONS

Modeling BERs predicts final outcome, and high %LB + AFB counts 3-4 weeks into therapy may identify a persister bacterial phenotype. These methods deserve further evaluation as surrogate endpoints for clinical trials.