Factors that complicate the treatment of tuberculosis in HIV-infected patients

The Prognosis for Delayed Immune Recovery in HIV-Infected Children might be Associated with Pre-cART CD4 + T cell Count Irrespective of Co-Infection with Tuberculosis

Background : Immune reconstitution following the initiation of combination antiretroviral therapy (cART) significantly impacts the prognosis of individuals infected with human immunodeficiency virus (HIV). Our previous studies have indicated that the baseline CD4 + T cells count and percentage before cART initiation are predictors of immune recovery in TB-negative children infected with HIV, with TB co-infection potentially causing a delay in immune recovery. However, it remains unclear whether these predictors consistently impact immune reconstitution during long-term intensive cART treatment in TB-negative/positive children infected with HIV. Results : We confirmed that the baseline CD4 + T cell count is a significant predictor of immune recovery following long-term intensive cART treatment among children aged 5 to 18 years. Children with lower CD4 + T cell count prior cART initiation did not show substantial immunological recovery during the follow-up period. Interestingly, children who were co-infected with TB and had higher baseline CD4 + T cell count eventually achieved good immunological recovery comparable to the TB-negative HIV-infected children. Hence, the baseline CD4 + T cell count at the onset of treatment serves as a reliable predictor of immunological reconstitution in HIV-infected children with or without TB co-infection. Taken together, this follow-up study validates our previous findings and further establishes that initiating cART early alongside early HIV testing can help prevent the diminished CD4 + T cell count associated with inadequate immunological reconstitution.

Magnitude and associated factors of virological failure among children on ART in Bahir Dar Town public health facilities, Northwest Ethiopia: a facility based cross-sectional study

Background

Despite the rapid scale-up of antiretroviral therapy, virologic failure has become global public health concern and challenge, especially in developing countries. Viral load monitoring is an important approach to identify treatment failure and develop public health interventions in children receiving antiretroviral therapy. Thus, this study aims to assess the magnitude and associated factors of virological failure among children on antiretroviral therapy.

Methods

A facility-based cross-sectional study was conducted among 399 HIV-positive children on antiretroviral therapy from 2016 to 2019 in Bahir Dar Town public health facilities. Data were extracted from children’s charts using a standardized data extraction tool, adapted from ART intake and follow-up forms. Data were entered using Epi-Data Version 3.1, and analyzed using SPSS Version 25. Bivariable and multivariable binary logistic regression models were done to identify factors associated with virological failure. Variables with p-values < 0.25 were fitted into the multivariable analysis. Finally, variables with p-values <0.05 were considered as statistically significant factors.

Results

The period prevalence of virological failure was found to be 14.8% (95% CI: 11.5–19.3%). Opportunistic infections (AOR = 2.19, CI: 1.13–4.25), history of treatment interruption and restart (AOR = 2.21, CI: 1.09–4.54), younger age (AOR = 2.42, CI: 1.02–5.74), poor/fair ART adherence (AOR = 2.19, CI: 1.05–4.57), and advanced baseline WHO clinical staging (AOR = 2.32, CI: 1.14–4.74) were found to be factors significantly associated with virological failure.

Conclusion

The magnitude of virological failure among HIV-infected children remained high. Children with poor/fair ART adherence, history of treatment interruption, advanced baseline WHO clinical staging, younger age, and opportunistic infections were significantly associated with virologic failure. Thus, special attention should be given to children who had poor/fair ART adherence and presenting with opportunistic infections.

Pre-HAART CD4+ T-lymphocytes as biomarkers of post-HAART immune recovery in HIV-infected children with or without TB co-infection

BACKGROUND

Infection with the Human Immunodeficiency Virus (HIV) dramatically increases the risk of developing active tuberculosis (TB). Several studies have indicated that co-infection with TB increases the risk of HIV progression and death. Sub-Saharan Africa bears the brunt of these dual epidemics, with about 2.4 million HIV-infected people living with TB. The main objective of our study was to assess whether the pre-HAART CD4+ T-lymphocyte counts and percentages could serve as biomarkers for post-HAART treatment immune-recovery in HIV-positive children with and without TB co-infection.

METHODS

The data analyzed in this retrospective study were collected from a cohort of 305 HIV-infected children being treated with HAART. A Lehmann family of ROC curves were used to assess the diagnostic performance of pre- HAART treatment CD4+ T-lymphocyte count and percentage as biomarkers for post-HAART immune recovery. The Kaplan-Meier estimator was used to compare differences in post-HAART recovery times between patients with and without TB co-infection.

RESULTS

We found that the diagnostic performance of both pre-HARRT treatment CD4+ T-lymphocyte count and percentage was comparable and achieved accuracies as high as 74%. Furthermore, the predictive capability of pre-HAART CD4+ T-lymphocyte count and percentage were slightly better in TB-negative patients. Our analyses also indicate that TB-negative patients have a shorter recovery time compared to the TB-positive patients.

CONCLUSIONS

Pre-HAART CD4+ T-lymphocyte count and percentage are stronger predictors of immune recovery in TB-negative pediatric patients, suggesting that TB co-infection complicates the treatment of HIV in this cohort. These findings suggest that the detection and treatment of TB is essential for the effectiveness of HAART in HIV-infected pediatric patients.

Mortality rate among HIV-positive children on ART in Northwest Ethiopia: a historical cohort study

Background

Though highly active antiretroviral therapy (HAART) has been available for more than a decade in Ethiopia, information regarding mortality rates of human immunodeficiency virus (HIV)-positive children after antiretroviral therapy antiretroviral therapy (ART) initiation is very scarce. Thus, this study intends to determine the predictors of mortality among HIV-positive children receiving ART in Amhara Region.

Methods

A multicenter facility-based historical cohort study was conducted in 538 HIV-positive children on ART from January 2012 to February 2017. We employed a standardized data extraction tool, adapted from ART entry and follow-up forms. Descriptive analyses were summarized using the Kaplan-Meier survival curve and log rank test. Then, the Cox-proportional hazard regression model was employed to estimate the hazard of death up to five-years after ART initiation. Variables with p-values ≤0.25 in bivariable analysis were candidates to the multivariable analysis. Finally, variables with p-values < 0.05 were considered as significant variables.

Results

The cohort contributed a total follow-up time of 14,600 child-months, with an overall mortality rate of 3.2 (95% CI: 2.3, 4.3) per 100 child-years. This study also indicated that HIV-infected children presenting with opportunistic infections (OIs) (AHR: 2.5, 95% CI: 1.04, 5.9), anemia (AHR: 3.1, 95% CI: 1.4, 6.7), severe immunodeficiency (AHR: 4.4, 95% CI: 1.7, 11.7), severe stunting (AHR: 3.3, 95% CI: 1.4, 8.0), severe wasting (AHR: 3.1, 95% CI: 1.3, 7.3), and advanced disease staging (III and IV) (AHR: 3.0, 95% CI: 1.2, 7.1) were at higher risk of mortality.

Conclusion

A higher rate of mortality was observed in our study as compared to previous Ethiopian studies. HIV-positive children presenting with anemia, OIs, severe immunodeficiency, advanced disease staging (III and IV), severe stunting, and severe wasting were at higher risk of mortality.

Bedaquiline, moxifloxacin, pretomanid, and pyrazinamide during the first 8 weeks of treatment of patients with drug-susceptible or drug-resistant pulmonary tuberculosis: a multicentre, open-label, partially randomised, phase 2b trial

BACKGROUND

New anti-tuberculosis regimens that are shorter, simpler, and less toxic than those that are currently available are needed as part of the global effort to address the tuberculosis epidemic. We aimed to investigate the bactericidal activity and safety profile of combinations of bedaquiline, pretomanid, moxifloxacin, and pyrazinamide in the first 8 weeks of treatment of pulmonary tuberculosis.

METHODS

In this multicentre, open-label, partially randomised, phase 2b trial, we prospectively recruited patients with drug-susceptible or rifampicin-resistant pulmonary tuberculosis from seven sites in South Africa, two in Tanzania, and one in Uganda. Patients aged 18 years or older with sputum smear grade 1+ or higher were eligible for enrolment, and a molecular assay (GeneXpert or MTBDRplus) was used to confirm the diagnosis of tuberculosis and to distinguish between drug-susceptible and rifampicin-resistant tuberculosis. Patients who were HIV positive with a baseline CD4 cell count of less than 100 cells per uL were excluded. Patients with drug-susceptible tuberculosis were randomly assigned (1:1:1) using numbered treatment packs with sequential allocation by the pharmacist to receive 56 days of treatment with standard tuberculosis therapy (oral isoniazid, rifampicin, pyrazinamide, and ethambutol; HRZE), or pretomanid (oral 200 mg daily) and pyrazinamide (oral 1500 mg daily) with either oral bedaquiline 400 mg daily on days 1-14 then 200 mg three times per week (B_loadPaZ) or oral bedaquiline 200 mg daily (B₂₀₀PaZ). Patients with rifampicin-resistant tuberculosis received 56 days of the B₂₀₀PaZ regimen plus moxifloxacin 400 mg daily (BPaMZ). All treatment groups were open label, and randomisation was not stratified. Patients, trial investigators and staff, pharmacists or dispensers, laboratory staff (with the exception of the mycobacteriology laboratory staff), sponsor staff, and applicable contract research organisations were not masked. The primary efficacy outcome was daily percentage change in time to sputum culture positivity (TTP) in liquid medium over days 0-56 in the drug-susceptible tuberculosis population, based on non-linear mixed-effects regression modelling of log₁₀ (TTP) over time. The efficacy analysis population contained patients who received at least one dose of medication and who had efficacy data available and had no major protocol violations. The safety population contained patients who received at least one dose of medication. This study is registered with ClinicalTrials.gov, NCT02193776, and all patients have completed follow-up.

FINDINGS

Between Oct 24, 2014, and Dec 15, 2015, we enrolled 180 patients with drug-susceptible tuberculosis (59 were randomly assigned to B_loadPaZ, 60 to B₂₀₀PaZ, and 61 to HRZE) and 60 patients with rifampicin-resistant tuberculosis. 57 patients in the B_loadPaZ group, 56 in the B₂₀₀PaZ group, and 59 in the HRZE group were included in the primary analysis. B₂₀₀PaZ produced the highest daily percentage change in TTP (5·17% [95% Bayesian credibility interval 4·61-5·77]), followed by B_loadPaZ (4·87% [4·31-5·47]) and HRZE group (4·04% [3·67-4·42]). The bactericidal activity in B₂₀₀PaZ and B_loadPaZ groups versus that in the HRZE group was significantly different. Higher proportions of patients in the B_loadPaZ (six [10%] of 59) and B₂₀₀PaZ (five [8%] of 60) groups discontinued the study drug than in the HRZE group (two [3%] of 61) because of adverse events. Liver enzyme elevations were the most common grade 3 or 4 adverse events and resulted in the withdrawal of ten patients (five [8%] in the B_loadPaZ group, three [5%] in the B₂₀₀PaZ group, and two [3%] in the HRZE group). Serious treatment-related adverse events affected two (3%) patients in the B_loadPaZ group and one (2%) patient in the HRZE group. Seven (4%) patients with drug-susceptible tuberculosis died and four (7%) patients with rifampicin-resistant tuberculosis died. None of the deaths were considered to be related to treatment.

INTERPRETATION

B₂₀₀PaZ is a promising regimen to treat patients with drug-susceptible tuberculosis. The bactericidal activity of both these regimens suggests that they have the potential to shorten treatment, and the simplified dosing schedule of B₂₀₀PaZ could improve treatment adherence in the field. However, these findings must be investigated further in a phase 3 trial assessing treatment outcomes.

FUNDING

TB Alliance, UK Department for International Development, Bill & Melinda Gates Foundation, US Agency for International Development, Directorate General for International Cooperation of the Netherlands, Irish Aid, Australia Department of Foreign Affairs and Trade, and the Federal Ministry for Education and Research of Germany.

Toxicity related to standard TB therapy for pulmonary tuberculosis and treatment outcomes in the REMoxTB study according to HIV status

BACKGROUND

The phase III REMoxTB study prospectively enrolled HIV-positive (with CD4+ count > 250 cells, not on anti-retroviral therapy) and HIV-negative patients. We investigated the incidence of adverse events and cure rates according to HIV status for patients receiving standard TB therapy in the trial.

METHODS

Forty-two HIV-positive cases were matched to 220 HIV-negative controls by age, gender, ethnicity, and trial site using coarsened exact matching. Grade 3 and 4 adverse events (AEs) were summarised by MedDRA System Organ Class. Kaplan-Meier curves for time to first grade 3 or 4 AE were constructed according to HIV status with hazard ratios calculated. Patients were considered cured if they were culture negative 18 months after commencing therapy with ≥2 consecutive negative culture results.

RESULTS

Twenty of 42 (47.6%) HIV-positive and 34 of 220 (15.5%) HIV-negative patients experienced ≥1 grade 3 or 4 AE, respectively. The majority of these were hepatobiliary disorders that accounted for 12 of 40 (30.0%) events occurring in 6 of 42 (14.3%) HIV-positive patients and for 15 of 60 (25.0%) events occurring in 9 of 220 (4.1%) HIV-negative patients. The median time to first grade 3 or 4 AE was 54 days (IQR 15.5-59.0) for HIV-positive and 29.5 days (IQR 9.0-119.0) for HIV-negative patients, respectively. The hazard ratio for experiencing a grade 3 or 4 AE among HIV-positive patients was 3.25 (95% CI 1.87-5.66, p < 0.01). Cure rates were similar, with 38 of 42 (90.5%) HIV-positive and 195 of 220 (88.6%) HIV-negative patients (p = 0.73) cured at 18 months.

CONCLUSIONS

HIV-positive patients receiving standard TB therapy in the REMoxTB study were at greater risk of adverse events during treatment but cure rates were similar when compared to a matched sample of HIV-negative patients.

EASL Clinical Practice Guidelines: Drug-induced liver injury

Idiosyncratic (unpredictable) drug-induced liver injury is one of the most challenging liver disorders faced by hepatologists, because of the myriad of drugs used in clinical practice, available herbs and dietary supplements with hepatotoxic potential, the ability of the condition to present with a variety of clinical and pathological phenotypes and the current absence of specific biomarkers. This makes the diagnosis of drug-induced liver injury an uncertain process, requiring a high degree of awareness of the condition and the careful exclusion of alternative aetiologies of liver disease. Idiosyncratic hepatotoxicity can be severe, leading to a particularly serious variety of acute liver failure for which no effective therapy has yet been developed. These Clinical Practice Guidelines summarize the available evidence on risk factors, diagnosis, management and risk minimization strategies for drug-induced liver jury.

Oxidative Stress and First-Line Antituberculosis Drug-Induced Hepatotoxicity

Hepatotoxicity induced by antituberculosis drugs is a serious adverse reaction with significant morbidity and even, rarely, mortality. This form of toxicity potentially impacts the treatment outcome of tuberculosis in some patients. Covering only first-line antituberculosis drugs, this review addresses whether and how oxidative stress and, more broadly, disturbance in redox homeostasis alongside mitochondrial dysfunction may contribute to the hepatotoxicity induced by them. Risk factors for such toxicity that have been identified, in addition to genetic factors, principally include old age, malnutrition, alcoholism, chronic hepatitis C and chronic hepatitis B infection, HIV infection, and preexisting liver disease. Importantly, these comorbid conditions are associated with oxidative stress. Thus, the shared pathogenetic mechanism(s) for liver injury might be in operation due to disease-drug interaction. Our current ability to predict, prevent, or treat hepatotoxicity (other than removing potentially hepatotoxic drugs) remains limited. More translational research to unravel the pathogenesis, inclusive of the underlying molecular basis, regarding antituberculosis drug-induced hepatotoxicity is needed, and so is clinical research pertaining to the advances in therapy with antioxidants and drugs related to antioxidants, especially those for management of mitochondrial dysfunction. The role of pharmacogenetics in the clinical management of drug-induced hepatotoxicity also likely merits further evaluation.

Anti-TB drug concentrations and drug-associated toxicities among TB/HIV-coinfected patients

Background

Toxicities due to anti-TB treatment frequently occur among TB/HIV-coinfected patients.

Objectives

To determine the association between anti-TB drug concentrations and the occurrence of hepatotoxicity and peripheral neuropathy among TB/HIV-coinfected patients.

Methods

TB/HIV-coinfected patients were started on standard dose anti-TB treatment according to WHO guidelines. Anti-TB drug concentrations were measured using HPLC 1, 2 and 4 h after drug intake at 2, 8 and 24 weeks following initiation of TB treatment. Participants were assessed for hepatotoxicity using Division of AIDS toxicity tables and for peripheral neuropathy using clinical assessment of tendon reflexes, vibration sensation or symptoms. Cox regression was used to determine the association between toxicities and drug concentrations.

Results

Of the 268 patients enrolled, 58% were male with a median age of 34 years. Participants with no hepatotoxicity or mild, moderate and severe hepatotoxicity had a median C max of 6.57 (IQR 4.83-9.41) μg/mL, 7.39 (IQR 5.10-10.20) μg/mL, 7.00 (IQR 6.05-10.95) μg/mL and 3.86 (IQR 2.81-14.24) μg/mL, respectively. There was no difference in the median C max of rifampicin among those who had hepatotoxicity and those who did not ( P  =   0.322). There was no difference in the isoniazid median C max among those who had peripheral neuropathy 2.34 (1.52-3.23) μg/mL and those who did not 2.21 (1.45-3.11) μg/mL ( P  =   0.49).

Conclusions

There was no association between rifampicin concentrations and hepatotoxicity or isoniazid concentrations and peripheral neuropathy among TB/HIV-coinfected patients.

Cohort profile of a study on outcomes related to tuberculosis and antiretroviral drug concentrations in Uganda: design, methods and patient characteristics of the SOUTH study

PURPOSE

Tuberculosis (TB) is a leading cause of death among people living with HIV in sub-Saharan Africa. Several factors influence the efficacy of TB treatment by leading to suboptimal drug concentrations and subsequently affecting treatment outcome. The aim of this cohort is to determine the association between anti-TB drug concentrations and TB treatment outcomes.

PARTICIPANTS

Patients diagnosed with new pulmonary TB at the integrated TB-HIV outpatient clinic in Kampala, Uganda, were enrolled into the study and started on first-line anti-TB treatment.

FINDINGS TO DATE

Between April 2013 and April 2015, the cohort enrolled 268 patients coinfected with TB/HIV ; 57.8% are male with a median age of 34 years (IQR 29-40). The median time between the diagnosis of HIV and the diagnosis of TB is 2 months (IQR 0-22.5). The majority of the patients are antiretroviral therapy naive (75.4%). Our population is severely immunosuppressed with a median CD4 cell count at enrolment of 163 cells/µL (IQR 46-298). Ninety-nine per cent of the patients had a diagnosis of pulmonary TB confirmed by sputum microscopy, Xpert/RIF or culture and 203 (75.7%) have completed TB treatment with 5099 aliquots of blood collected for pharmacokinetic analysis.

FUTURE PLANS

This cohort provides a large database of well-characterised patients coinfected with TB/HIV which will facilitate the description of the association between serum drug concentrations and TB treatment outcomes as well as provide a research platform for future substudies including evaluation of virological outcomes.

TRIAL REGISTRATION NUMBER

NCT01782950; Pre-results.

Programmatic and ethical challenges in the implementation of treatment-as-prevention in the context of HIV and drug-resistant tuberculosis co-infection in sub-Saharan Africa

There is limited literature on programmatic challenges in the implementation of a treatment-as-prevention (TasP) strategy among human immunodeficiency virus (HIV) and drug-resistant tuberculosis (DR-TB) co-infected individuals in sub-Saharan Africa (SSA). This paper highlights specific programmatic challenges surrounding the implementation of this strategy among HIV and DR-TB co-infected populations in SSA. In SSA, limitations in administrative, human and financial resources and poor health infrastructure, as well as increased duration and complexity of providing long-term treatment for HIV individuals co-infected with DR-TB, pose substantial challenges to the implementation of a TasP strategy and warrant further investigation. A comprehensive approach must be devised to implement TasP strategy, with special attention paid to the sizable HIV and DR-TB co-infected populations. We suggest that evidence-informed and human rights-based guidelines for participant protection and strategies for programme delivery must be developed and tailored to maximise the benefits to those most at risk of developing HIV and DR-TB co-infection. Assessing regional circumstances is crucial, and TasP programmes in the region should be complemented by combined prevention strategies to achieve the intended goals.

Hepatotoxicity Related to Anti-tuberculosis Drugs: Mechanisms and Management

Development of idiosyncratic hepatotoxicity is an intricate process involving both concurrent as well as sequential events determining the direction of the pathways, degree of liver injury and its outcome. Decades of clinical observation have identified a number of drug and host related factors that are associated with an increased risk of antituberculous drug-induced hepatotoxicity, although majority of the studies are retrospective with varied case definitions and sample sizes. Investigations on genetic susceptibility to hepatotoxicity have so far focused on formation and accumulation reactive metabolite as well as factors that contribute to cellular antioxidant defense mechanisms and the environment which can modulate the threshold for hepatocyte death secondary to oxidative stress. Recent advances in pharmacogenetics have promised the development of refined algorithms including drug, host and environmental risk factors that allow better tailoring of medications based on accurate estimates of risk-benefit ratio. Future investigations exploring the pathogenesis of hepatotoxicity should be performed using human tissue and samples whenever possible, so that the novel findings can be translated readily into clinical applications.

HIV-specific health care utilization and mortality among tuberculosis/HIV coinfected persons

Persons coinfected with tuberculosis (TB) and HIV are at high risk of death, in part due to suboptimal utilization of HIV-specific health care. We sought to better understand HIV-associated health care utilization and mortality in a retrospective cohort of TB/HIV coinfected cases reported in North Carolina 1993-2003. In this cohort, HIV was newly diagnosed during TB presentation for 34.2% of coinfected patients. Patients had advanced HIV (median CD4 104 cells/mm(3)) at TB diagnosis. Of 260 patients previously known to be HIV positive, 32.3% had seen a physician for HIV care in the previous 6 months and only 18.5% were taking antiretrovirals when TB was diagnosed; 34.8% of patients started antiretrovirals during TB treatment. Twenty-seven (5%) patients died prior to starting TB treatment; of those who survived, 13.6% (70/515) died prior to completing TB treatment, and 42.7% (220/515) died during a median 1408 days of follow-up. CD4 count (relative risk [RR] 0.53 per 100 cell increase, 95% confidence interval [CI] 0.34, 1.02) and highly active antiretroviral therapy (HAART) use during TB therapy (RR 0.37, 95% CI 0.13, 1.02) were independently associated with decreased mortality, while age greater than 45 (RR 2.18, 95% CI 1.11, 4.29) was independently associated with increased mortality during TB treatment. We conclude that TB/HIV coinfected patients had low utilization rates of HIV-specific care prior to TB diagnosis. Many did not receive potentially lifesaving HIV treatment while on TB therapy, and mortality was high as a result. Interventions to enhance utilization of HIV-related health care and integration of TB and HIV services should be studied to improve outcomes.

Long-term effectiveness of diagnosing and treating latent tuberculosis infection in a cohort of HIV-infected and at-risk injection drug users

INTRODUCTION

Between 1990 and 1998, tuberculin skin tests (TST) and isoniazid preventive therapy (IPT) were provided to injection drug users participating in the AIDS Linked to the Intravenous Experiences cohort.

METHODS

A registry match was conducted with the AIDS Linked to the Intravenous Experiences cohort database and the Maryland State Department of Health and Mental Hygiene tuberculosis registry.

RESULTS

Of 2010 participants, 1753 (74%) had a TST placed and read; 536 (31%) were positive. TST positivity was 16% in HIV positives; 39% in HIV negatives (P<0.01). Overall, 299 (56%) TST reactors started IPT; 165 (55%) completed 6 months. Three tuberculosis (TB) cases were diagnosed among HIV negatives (incidence rate=0.16/1000 person-years); 19 among HIV positives (1.94/1000 person-years; incidence rate ratio=12.3 (3.61-64.70). Within the entire cohort, TB rates were 0.81 per 1000 person-years for those not receiving IPT, 0.48 per 1000 person-years for those receiving any IPT, 0.29 per 1000 person-years for those completing at least 30 days, and 0 per 1000 person-years for completers. Ten cases of TB occurred in HIV-infected individuals with negative TSTs.

DISCUSSION

IPT was associated with protection against TB, but uptake was modest. Although it is likely that TB incidence would have increased, especially in HIV-positive subjects, if the IPT program had not occurred, more significant declines in TB incidence in this population will require improved methods for ensuring uptake and completion of IPT and preventing disease in TST-negative individuals.

Complications of Antiretroviral Therapy in Patients with Tuberculosis: Drug Interactions, Toxicity, and Immune Reconstitution Inflammatory Syndrome

Access to antiretroviral therapy is rapidly expanding in resource-limited settings, where tuberculosis is the most common opportunistic infection. Coadministration of antitubercular and antiretroviral agents is, therefore, occurring commonly, and it is associated with 3 major complications. First, induction of cytochrome P-450 enzymes and P-glycoprotein by rifampin results in reduced concentrations of nonnucleoside reverse-transcriptase inhibitors and, particularly, protease inhibitors. This potentially results in the loss of antiviral efficacy and the development of viral resistance. Replacing rifampin with rifabutin, which does not significantly affect the concentrations of antiretroviral agents, is advocated but is currently unaffordable in resource-limited settings. Second, overlapping toxicities of antitubercular and antiretroviral agents occur frequently, necessitating discontinuation of therapy and increasing the risk of nonadherence. Third, immunopathological reactions, termed "the immune reconstitution inflammatory syndrome," occur frequently when antiretroviral therapy is initiated in patients with tuberculosis. These complexities of coadministration of antitubercular and antiretroviral agents are reviewed, and research priorities are highlighted.

Integration and co-location of HIV/AIDS, tuberculosis and drug treatment services

Injection drug use (IDU) plays a critical role in the HIV epidemic in several countries throughout the world. In these countries, injection drug users are at significant risk for both HIV and tuberculosis, and active IDU negatively impacts treatment access, adherence and retention. Comprehensive strategies are therefore needed to effectively deliver preventive, diagnostic and curative services to these complex patient populations. We propose that developing co-located integrated care delivery systems should become the focus of national programmes as they continue to scale-up access to antiretroviral medications for drug users. Existing data suggest that such a programme will expand services for each of these diseases; increase detection of tuberculosis (TB) and HIV; improve medication adherence; increase entry into substance use treatment; decrease the likelihood of adverse drug events; and improve the effectiveness of prevention interventions. Key aspects of integration programmes include: co-location of services convenient to the patient; provision of effective substance use treatment, including pharmacotherapies; cross-training of generalist and specialist care providers; and provision of enhanced monitoring of drug-drug interactions and adverse side effects. Central to implementing this agenda will be fostering the political will to fund infrastructure and service delivery, expanding street-level outreach to IDUs, and training community health workers capable of cost effectively delivering these services.

An official ATS statement: hepatotoxicity of antituberculosis therapy

Drug-induced liver injury (DILI) is a problem of increasing significance, but has been a long-standing concern in the treatment of tuberculosis (TB) infection. The liver has a central role in drug metabolism and detoxification, and is consequently vulnerable to injury. The pathogenesis and types of DILI are presented, ranging from hepatic adaptation to hepatocellular injury. Knowledge of the metabolism of anti-TB medications and of the mechanisms of TB DILI is incomplete. Understanding of TB DILI has been hampered by differences in study populations, definitions of hepatotoxicity, and monitoring and reporting practices. Available data regarding the incidence and severity of TB DILI overall, in selected demographic groups, and in those coinfected with HIV or hepatitis B or C virus are presented. Systematic steps for prevention and management of TB DILI are recommended. These include patient and regimen selection to optimize benefits over risks, effective staff and patient education, ready access to care for patients, good communication among providers, and judicious use of clinical and biochemical monitoring. During treatment of latent TB infection (LTBI) alanine aminotransferase (ALT) monitoring is recommended for those who chronically consume alcohol, take concomitant hepatotoxic drugs, have viral hepatitis or other preexisting liver disease or abnormal baseline ALT, have experienced prior isoniazid hepatitis, are pregnant or are within 3 months postpartum. During treatment of TB disease, in addition to these individuals, patients with HIV infection should have ALT monitoring. Some experts recommend biochemical monitoring for those older than 35 years. Treatment should be interrupted and, generally, a modified or alternative regimen used for those with ALT elevation more than three times the upper limit of normal (ULN) in the presence of hepatitis symptoms and/or jaundice, or five times the ULN in the absence of symptoms. Priorities for future studies to develop safer treatments for LTBI and for TB disease are presented.