Infections with Mycobacterium tuberculosis and Mycobacterium avium among HIV-infected patients after the introduction of highly active antiretroviral therapy. EuroSIDA Study Group JD

Changing Incidence and Characteristics of Nontuberculous Mycobacterial Infections in Scotland and Comparison With Mycobacterium tuberculosis Complex Incidence (2011 to 2019)

Background

An increase in infections with nontuberculous mycobacteria (NTM) has been noted globally, and their incidence has overtaken that of Mycobacterium tuberculosis complex (MTBc) in many countries. Using data from a national reference laboratory, we aimed to determine if this trend could be observed in Scotland.

Methods

We undertook a retrospective review of all NTM isolates received by the Scottish Mycobacteria Reference Laboratory (SMRL) over 9 years from 2011 to 2019 inclusive. Clinical episodes were defined as per 2017 British Thoracic Society and 2020 American Thoracic Society/European Respiratory Society/European Society of Clinical Microbiology and Infectious Diseases/Infectious Diseases Society of America NTM guidelines. These rates were compared with Scottish tuberculosis rates over the same period.

Results

Of 8552 NTM isolates from 4586 patients in 2011 to 2019, 7739 (90.5%) were considered clinically relevant. These represented 2409 episodes of NTM infection, with M. avium, M. intracellulare, and M. abscessus complex being most common. A total of 1953 (81.1%) were pulmonary NTM infection episodes from 1470 patients and 456 extrapulmonary episodes from 370 patients. We estimated a rise in incidence from 3.4 to 6.5 per 100 000 person-years (2011-2019 inclusive), with an increase in NTM incidence over MTBc incidence in Scotland by 2017.

Conclusions

The incidence of NTM infection in Scotland has overtaken MTBc incidence. NTM infection leads to a costly health care burden, possibly as much as UK£1.47 million (US$ and €1.73 million) annually. We recommend standardization of isolate referral with clinical surveillance and implementation of agreed standards of care delivered through multidisciplinary teams. This would improve diagnosis and patient management as well as assessment of diagnostics and novel treatments through clinical trials.

Varying clinical presentations of nontuberculous mycobacterial disease : Similar to but different from tuberculosis

The incidence rate of pulmonary nontuberculous mycobacterial disease (PNTMD) in Japan is the highest among major industrialized nations. Although the typical clinical course and radiological manifestations of PNTMD are different from those of pulmonary tuberculosis (TB), confusion about these mycobacterial diseases leads to a diagnostic pitfall. Diagnostic challenges include the coexistence of Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM), false positives for NTM in MTB nucleic acid amplification tests, microbial substitution, and abnormal radiological manifestations caused by NTM. Features of extrapulmonary NTM diseases, such as pleurisy, vertebral osteomyelitis, and disseminated disease, are different from the corresponding tuberculous diseases. Moreover, the immunological background of the patient (status of human immunodeficiency virus infection with or without antiviral therapy, continuation or discontinuation of immunosuppressive therapy, use of immune checkpoint inhibitor, pregnancy and delivery, etc.) influences the pathophysiology of mycobacterial diseases. This review describes the varying clinical presentations of NTM disease with emphasis on the differences from TB. J. Med. Invest. 68 : 220-227, August, 2021.

How Far Does Highly Active Antiretroviral Treatment Reduce TB Incidence among Children? A Marginal Structural Modeling Analysis, Southwest Ethiopia

Background

Children younger than 15 years, carry almost 80% of the global burden of HIV/AIDS. HIV worsens the progression of latent TB to active TB disease. Although antiretroviral treatment has shown marked reduction in Tuberculosis incidence, TB continues to occur in Sub-Saharan countries including Ethiopia. The aim of this study was to investigate the impact of HAART on the incidence of tuberculosis among children infected with HIV in Southwest Ethiopia.

Methods

A retrospective cohort study was conducted between 2009 to 2014. We used chi-square test, and Mann-Whitney U test to compare non-HAART and HAART cohort. We estimated the effect of HAART on TB incidence using marginal structural model after adjusting for time-dependent confounders affected by exposure.

Result

A total of 844 children were followed. We observed them for a median of 51 months (IQR 31) and a total of 2942.99 child-years. The overall TB incidence rate was 7.917 per 100 child years (95% CI, 6.933–9.002). TB incidence for specific HAART and non-HAART cohort were 7.67 per 100 child-years (95% CI, 6.318–9.217) and 8.17 per 100 child-years (95% CI, 6.772–9.767) respectively. From marginal structural modeling, children on HAART were 36% (HR=0.642, 95% CI 0.442–0.931, p<0.02) less likely to develop TB compared to those who were not.

Conclusion

HAART reduced the hazard of TB in HIV-infected children by 36%. This is by far less than what is expected.

Effect of highly active antiretroviral treatment on TB incidence among HIV infected children and their clinical profile, retrospective cohort study, South West Ethiopia

Globally, 1.8 million HIV infected children live with HIV; nearly 53% of them were receiving HIV treatment. People who are infected with HIV are 18 times more likely to develop active TB. Despite antiretroviral treatment has shown marked reduction in TB incidence, TB continues to occur in Sub-Saharan countries including Ethiopia among HIV infected people. The effect of highly active antiretroviral treatment is quite successful in developed countries. However, in developing country TB/HIV co-infection remains perplexing among children on the treatment. The aim of this study was to investigate the impact of ART on the incidence of TB among Children infected with HIV in Southwest Ethiopia. A retrospective cohort study was conducted on randomly selected 800 samples from ART clinic between 2009 and 2014. We used chi-square test, and Mann–Whitney U test to compare HAART naïve and HAART cohort. We used marginal structural models to estimate the effect of HAART on survival while accounting for time-dependent confounders affected by exposure. A total of 800 children were followed for 2942.99 child-years. The children were observed for a median of 51 months with IQR 31 and for a total of 2942.99 child-years. From 506 OIs that occurred, the most common reported OIs were Pneumonia (22%) and TB (23.6%). The overall TB incidence rate was 7.917 per 100 child years (95% CI, 6.933–9.002). Whereas among HAART (7.667 per 100-years (95% CI, 6.318–9.217) and 8.1686 per 100 person-years (95% CI 6.772–9.767) for HAART naïve. The mortality hazard ratio comparing HAART with no HAART from a marginal structural model was 0.642 (95% CI 0.442–0.931, p < 0.02). HAART reduced the hazard of TB in HIV-infected children by 36%. This is by far less than expected.

Diagnostic discrepancy between bronchoalveolar lavage and transbronchial biopsy from bronchoscopies of HIV patients with pneumonia: toward an integral diagnosis

Background

The key diagnostic method for the evaluation of lung diseases associated with HIV infection is bronchoscopy, with bronchoalveolar lavage (BAL) being the most commonly used sampling technique. Transbronchial biopsy (TBB) is often complementary.

Setting

This is a retrospective cross-sectional study to determine the diagnostic usefulness of bronchoscopy with simultaneous samples obtained through BAL and TBB in HIV-infected patients with pneumonia at the National Institute of Respiratory Diseases Ismael Cosío Villegas.

Methods

In this cross-sectional study (January 2014-December 2015), the diagnostic yield of bronchoscopic samples from all HIV-positive patients with pneumonia aged >18 years, from procedures performed in the Interventional Pulmonology Unit, was analyzed and recorded in its database. The diagnostic yield concordance between BAL and TBB samples was evaluated by kappa index calculation.

Results

A total of 198 procedures on 189 HIV-infected patients with pneumonia were performed. A total of 167/189 (88.4%) patients were male, and the mean age was 34.7 years (SD ±9.0). Overall, the diagnostic yield for either technique was 87.9% (174/198), but it was higher for TBB, its yield being 78.8% (156/198). In contrast, that of BAL was 62.1% (123/198) (P=0.001). The overall diagnostic yield concordance between TBB and BAL was insignificant (k=0.213, P<0.001). It improved for fungal infections, pneumocystosis, and tuberculosis (k=0.417, 0.583, and 0.462, respectively, all P<0.001).

Conclusion

Our results show that the simultaneous obtainment of BAL and TBB samples is useful and complementary in the diagnosis of infections and malignancies in HIV-infected patients. Additionally, they are safe procedures in this group of patients.

Refining Current Scientific Priorities and Identifying New Scientific Gaps in HIV-Related Heart, Lung, Blood, and Sleep Research

The National Heart, Lung, and Blood Institute (NHLBI) AIDS Program's goal is to provide direction and support for research and training programs in areas of HIV-related heart, lung, blood, and sleep (HLBS) diseases. To better define NHLBI current HIV-related scientific priorities and with the goal of identifying new scientific priorities and gaps in HIV-related HLBS research, a wide group of investigators gathered for a scientific NHLBI HIV Working Group on December 14-15, 2015, in Bethesda, MD. The core objectives of the Working Group included discussions on: (1) HIV-related HLBS comorbidities in the antiretroviral era; (2) HIV cure; (3) HIV prevention; and (4) mechanisms to implement new scientific discoveries in an efficient and timely manner so as to have the most impact on people living with HIV. The 2015 Working Group represented an opportunity for the NHLBI to obtain expert advice on HIV/AIDS scientific priorities and approaches over the next decade.

Diagnosis and Management of a Pancreaticopleural Fistula in a Patient with AIDS and a Large Pleural Effusion

Pleural effusions typically present with nonspecific pulmonary complaints in the setting of either acute or chronic diseases. In the general population, these illnesses include congestive heart failure, infection, and malignancy. However, in people living with HIV/AIDS (PLWHA), pleural effusions often result from opportunistic infections and AIDS-defining malignancies, such as Kaposi sarcoma and non-Hodgkin lymphoma. Since the introduction of highly active antiretroviral therapy, there has been a decline in the frequency of AIDS-defining opportunistic infections and AIDS-defining cancers and an increase in certain non-AIDS-defining malignancies including lung cancer. Throughout this period, longer life expectancy in PLWHA has contributed to an increased risk of those chronic diseases that can result in pleural effusions. This case describes an HIV-infected man who was an active cigarette smoker and alcoholic and who presented with a large pleural effusion of uncertain etiology. The authors review several important noncardiac risk factors associated with pleural effusions in PLWHA. The authors also emphasize the importance of obtaining a detailed medical history and the use of appropriate imaging and laboratory tests in order to identify an underlying cause and to provide optimal treatment.

Risk of tuberculosis among HAART receiving HIV patients attending an ART centre of West Bengal, India: a prospective cohort study

This prospective study was conducted to find out the incidence density rate and to identify the attributed risk factors of Tuberculosis development among ART receivers. All patients who were registered in a nodal ART centre of India within 1st January 2008-31st December 2008 and had been initiated ART in the year of 2008 were considered as a cohort and were followed up till 31st December 2012. This study was started with 169 ART receivers and ended with 129 patients. During total 631.1 person-years observation, 39 TB cases (31 pulmonary and 8 extra pulmonary) were diagnosed. TB incidence density rate reduced from 12.08/100 to 1.12/100 person-years during the follow up periods. Cox regression model revealed that patients having past history of Tuberculosis were at 5 times higher risk (Hazard ratio = 5.205; 95 % CI 2.439-11.106; p = 0.000). Patients with WHO clinical stage 3 or 4 at the time of enrolment had 2 times more risk of development of TB (Hazard ratio = 2.081; 95 % CI 1.502-2.884; p = 0.000). This study highlighted that special attention should be paid on earliest identification of TB among the HIV patients who had past history of TB or suffering from WHO clinical stage 3 or 4 to prevent the silent transmission and multidrug resistance development of Tuberculosis in the community.

Aspartic peptidases of human pathogenic trypanosomatids: perspectives and trends for chemotherapy

Aspartic peptidases are proteolytic enzymes present in many organisms like vertebrates, plants, fungi, protozoa and in some retroviruses such as human immunodeficiency virus (HIV). These enzymes are involved in important metabolic processes in microorganisms/virus and play major roles in infectious diseases. Although few studies have been performed in order to identify and characterize aspartic peptidase in trypanosomatids, which include the etiologic agents of leishmaniasis, Chagas’ disease and sleeping sickness, some beneficial properties of aspartic peptidase inhibitors have been described on fundamental biological events of these pathogenic agents. In this context, aspartic peptidase inhibitors (PIs) used in the current chemotherapy against HIV (e.g., amprenavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir) were able to inhibit the aspartic peptidase activity produced by different species of Leishmania. Moreover, the treatment of Leishmania promastigotes with HIV PIs induced several perturbations on the parasite homeostasis, including loss of the motility and arrest of proliferation/growth. The HIV PIs also induced an increase in the level of reactive oxygen species and the appearance of irreversible morphological alterations, triggering parasite death pathways such as programed cell death (apoptosis) and uncontrolled autophagy. The blockage of physiological parasite events as well as the induction of death pathways culminated in its incapacity to adhere, survive and escape of phagocytic cells. Collectively, these results support the data showing that parasites treated with HIV PIs have a significant reduction in the ability to cause in vivo infection. Similarly, the treatment of Trypanosoma cruzi cells with pepstatin A showed a significant inhibition on both aspartic peptidase activity and growth as well as promoted several and irreversible morphological changes. These studies indicate that aspartic peptidases can be promising targets in trypanosomatid cells and aspartic proteolytic inhibitors can be benefic chemotherapeutic agents against these human pathogenic microorganisms.

HIV-Care Outcome in Saudi Arabia; a Longitudinal Cohort

Background

Clinical characteristics of HIV-1 infection in people inhabiting Western, Sub-Saharan African, and South-East Asian countries are well recognized. However, very little information is available with regard to HIV-1 infection and treatment outcome in MENA countries including the Gulf Cooperation Council (GCC) states.

Methods

Clinical, demographic and epidemiologic characteristics of 602 HIV-1 infected patients followed in the adult Infectious Diseases Clinic of King Faisal Specialist Hospital and Research Centre, in Riyadh, Kingdom of Saudi Arabia a tertiary referral center were longitudinally collected from 1989 to 2010.

Results

Of the 602 HIV-1 infected patients in this observation period, 70% were male. The major mode of HIV-1 transmission was heterosexual contact (55%). At diagnosis, opportunistic infections were found in 49% of patients, most commonly being pneumocysitis. AIDS associated neoplasia was also noted in 6% of patients. A hundred and forty-seven patients (24%) died from the cohort by the end of the observation period. The mortality rate peaked in 1992 at 90 deaths per 1000 person-year, whereas the mortality rate gradually decreased to <1% from 1993-2010. In 2010, 71% of the patients were receiving highly active retroviral therapy.

Conclusions

These data describe the clinical characteristic of HIV-1-infected patients at a major tertiary referral hospital in KSA over a 20-year period. Initiation of antiretroviral therapy resulted in a significant reduction in both morbidity and mortality. Future studies are needed in the design and implementation of targeted treatment and prevention strategies for HIV-1 infection in KSA.

Trends in overall opportunistic illnesses, Pneumocystis carinii pneumonia, cerebral toxoplasmosis and Mycobacterium avium complex incidence rates over the 30 years of the HIV epidemic: a systematic review

BACKGROUND

The natural history of HIV infection has changed dramatically after the introduction of highly active antiretroviral therapy. Currently, opportunistic illnesses still represent a major cause of death and hospitalization in this population. In this study, we review the trends in opportunistic illnesses incidence rates and compare the results observed in high-income settings with that for low/middle-income settings, with special attention given to studies from Brazil.

METHODS

We systematically searched Pubmed, Web of Science, Lilacs and Google scholar for publications on HIV associated opportunistic illness. Studies reporting rates based on person-time for all opportunistic illnesses and/or the three opportunistic infections of interest, namely, Pneumocystis carinii pneumonia, cerebral toxoplasmosis, and Mycobacterium avium complex were included.

RESULTS

Significant reductions in the incidence rates were demonstrated for opportunistic illnesses overall and also for the specific opportunistic infections included in the present study, both in high and low/middle-income settings. Out of the 37 studies included in the present review, almost 70% were from high-income settings. All the studies conducted in low/middle-income settings were single center studies and four were from Brazil. We found no study from Brazil reporting annual incidence rates of opportunistic illnesses.

CONCLUSIONS

Opportunistic illnesses remain an important public health problem. To better guide health policies in low/middle-income settings, multicenter cohort studies should be encouraged. Studies from Brazil are urgently needed to assess the current burden of opportunistic illnesses in our population and to support the planning of HIV/AIDS health care services organization.

The incidence of AIDS-defining illnesses at a current CD4 count ≥ 200 cells/μL in the post-combination antiretroviral therapy era

BACKGROUND

Few studies consider the incidence of individual AIDS-defining illnesses (ADIs) at higher CD4 counts, relevant on a population level for monitoring and resource allocation.

METHODS

Individuals from the Collaboration of Observational HIV Epidemiological Research Europe (COHERE) aged ≥14 years with ≥1 CD4 count of ≥200 µL between 1998 and 2010 were included. Incidence rates (per 1000 person-years of follow-up [PYFU]) were calculated for each ADI within different CD4 strata; Poisson regression, using generalized estimating equations and robust standard errors, was used to model rates of ADIs with current CD4 ≥500/µL.

RESULTS

A total of 12 135 ADIs occurred at a CD4 count of ≥200 cells/µL among 207 539 persons with 1 154 803 PYFU. Incidence rates declined from 20.5 per 1000 PYFU (95% confidence interval [CI], 20.0-21.1 per 1000 PYFU) with current CD4 200-349 cells/µL to 4.1 per 1000 PYFU (95% CI, 3.6-4.6 per 1000 PYFU) with current CD4 ≥ 1000 cells/µL. Persons with a current CD4 of 500-749 cells/µL had a significantly higher rate of ADIs (adjusted incidence rate ratio [aIRR], 1.20; 95% CI, 1.10-1.32), whereas those with a current CD4 of ≥1000 cells/µL had a similar rate (aIRR, 0.92; 95% CI, .79-1.07), compared to a current CD4 of 750-999 cells/µL. Results were consistent in persons with high or low viral load. Findings were stronger for malignant ADIs (aIRR, 1.52; 95% CI, 1.25-1.86) than for nonmalignant ADIs (aIRR, 1.12; 95% CI, 1.01-1.25), comparing persons with a current CD4 of 500-749 cells/µL to 750-999 cells/µL.

DISCUSSION

The incidence of ADIs was higher in individuals with a current CD4 count of 500-749 cells/µL compared to those with a CD4 count of 750-999 cells/µL, but did not decrease further at higher CD4 counts. Results were similar in patients virologically suppressed on combination antiretroviral therapy, suggesting that immune reconstitution is not complete until the CD4 increases to >750 cells/µL.

Impact of antiretroviral therapy on lung immunology and inflammation

Human immunodeficiency virus (HIV) infection causes profound changes in the lung compartment characterized by macrophage and lymphocyte activation, secretion of proinflammatory cytokines and chemokines, and accumulation of CD8 T cells in the alveolar space, leading to lymphocytic alveolitis. Because many of the changes seen in the lung can be attributed to the direct effect of HIV on immune cells, therapy to reduce the HIV burden should have significant beneficial effects. Indeed, antiretroviral therapy rapidly reduces the viral burden in the lung, number of CD8 T cells in the alveolar space, and amount of proinflammatory cytokines and chemokines in bronchoalveolar lavage.

T cells home to the thymus and control infection

The thymus is a target of multiple pathogens. How the immune system responds to thymic infection is largely unknown. Despite being considered an immune-privileged organ, we detect a mycobacteria-specific T cell response in the thymus following dissemination of Mycobacterium avium or Mycobacterium tuberculosis. This response includes proinflammatory cytokine production by mycobacteria-specific CD4(+) and CD8(+) T cells, which stimulates infected cells and controls bacterial growth in the thymus. Importantly, the responding T cells are mature peripheral T cells that recirculate back to the thymus. The recruitment of these cells is associated with an increased expression of Th1 chemokines and an enrichment of CXCR3(+) mycobacteria-specific T cells in the thymus. Finally, we demonstrate it is the mature T cells that home to the thymus that most efficiently control mycobacterial infection. Although the presence of mature T cells in the thymus has been recognized for some time, to our knowledge, these data are the first to show that T cell recirculation from the periphery to the thymus is a mechanism that allows the immune system to respond to thymic infection. Maintaining a functional thymic environment is essential to maintain T cell differentiation and prevent the emergence of central tolerance to the invading pathogens.

Impact of antiretroviral therapy on tuberculosis incidence among HIV-positive patients in high-income countries

BACKGROUND

The lower tuberculosis incidence reported in human immunodeficiency virus (HIV)-positive individuals receiving combined antiretroviral therapy (cART) is difficult to interpret causally. Furthermore, the role of unmasking immune reconstitution inflammatory syndrome (IRIS) is unclear. We aim to estimate the effect of cART on tuberculosis incidence in HIV-positive individuals in high-income countries.

METHODS

The HIV-CAUSAL Collaboration consisted of 12 cohorts from the United States and Europe of HIV-positive, ART-naive, AIDS-free individuals aged ≥18 years with baseline CD4 cell count and HIV RNA levels followed up from 1996 through 2007. We estimated hazard ratios (HRs) for cART versus no cART, adjusted for time-varying CD4 cell count and HIV RNA level via inverse probability weighting.

RESULTS

Of 65 121 individuals, 712 developed tuberculosis over 28 months of median follow-up (incidence, 3.0 cases per 1000 person-years). The HR for tuberculosis for cART versus no cART was 0.56 (95% confidence interval [CI], 0.44-0.72) overall, 1.04 (95% CI, 0.64-1.68) for individuals aged >50 years, and 1.46 (95% CI, 0.70-3.04) for people with a CD4 cell count of <50 cells/μL. Compared with people who had not started cART, HRs differed by time since cART initiation: 1.36 (95% CI, 0.98-1.89) for initiation <3 months ago and 0.44 (95% CI, 0.34-0.58) for initiation ≥3 months ago. Compared with people who had not initiated cART, HRs <3 months after cART initiation were 0.67 (95% CI, 0.38-1.18), 1.51 (95% CI, 0.98-2.31), and 3.20 (95% CI, 1.34-7.60) for people <35, 35-50, and >50 years old, respectively, and 2.30 (95% CI, 1.03-5.14) for people with a CD4 cell count of <50 cells/μL.

CONCLUSIONS

Tuberculosis incidence decreased after cART initiation but not among people >50 years old or with CD4 cell counts of <50 cells/μL. Despite an overall decrease in tuberculosis incidence, the increased rate during 3 months of ART suggests unmasking IRIS.

Activity of antiretroviral drugs in human infections by opportunistic agents

Highly active antiretroviral therapy (HAART) is used in patients infected with HIV. This treatment has been shown to significantly decrease opportunist infections such as those caused by viruses, fungi and particularly, protozoa. The use of HAART in HIV-positive persons is associated with immune reconstitution as well as decreased prevalence of oral candidiasis and candidal carriage. Antiretroviral therapy benefits patients who are co-infected by the human immunodeficiency virus (HIV), human herpes virus 8 (HHV-8), Epstein-Barr virus, hepatitis B virus (HBV), parvovirus B19 and cytomegalovirus (CMV). HAART has also led to a significant reduction in the incidence, and the modification of characteristics, of bacteremia by etiological agents such as Staphylococcus aureus, coagulase negative staphylococcus, non-typhoid species of Salmonella, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. HAART can modify the natural history of cryptosporidiosis and microsporidiosis, and restore mucosal immunity, leading to the eradication of Cryptosporidium parvum. A similar restoration of immune response occurs in infections by Toxoplasma gondii. The decline in the incidence of visceral leishmaniasis/HIV co-infection can be observed after the introduction of protease inhibitor therapy. Current findings are highly relevant for clinical medicine and may serve to reduce the number of prescribed drugs thereby improving the quality of life of patients with opportunistic diseases.

HIV-associated lung infections and complications in the era of combination antiretroviral therapy

The spectrum of lung diseases associated with HIV is broad, and many infectious and noninfectious complications of HIV infection have been recognized. The nature and prevalence of lung complications have not been fully characterized since the Pulmonary Complications of HIV Infection Study more than 15 years ago, before antiretroviral therapy (ART) increased life expectancy. Our understanding of the global epidemiology of these diseases in the current ART era is limited, and the mechanisms for the increases in the noninfectious conditions, in particular, are not well understood. The Longitudinal Studies of HIV-Associated Lung Infections and Complications (Lung HIV) Study (ClinicalTrials.gov number NCT00933595) is a collaborative multi-R01 consortium of research projects established by the National Heart, Lung, and Blood Institute to examine a diverse range of infectious and noninfectious pulmonary diseases in HIV-infected persons. This article reviews our current state of knowledge of the impact of HIV on lung health and the development of pulmonary diseases, and highlights ongoing research within the Lung HIV Study.

Tuberculosis among HIV-positive patients across Europe: changes over time and risk factors

OBJECTIVE

To describe temporal changes in the incidence rate of tuberculosis (TB) (pulmonary or extrapulmonary) among HIV-positive patients in western Europe and risk factors of TB across Europe.

METHODS

Poisson regression models were used to determine temporal changes in incidence rate of TB among 11,952 patients from western Europe (1994-2010), and to assess risk factors for TB among 12,673 patients from across Europe with follow-up after 2001.

RESULTS

Two hundred and seventy-seven TB events occurred during 84,221 person-years of follow-up (PYFU) in western Europe. The incidence rate declined from 1.91 [95% confidence interval (CI) 1.51-2.37)] in 1994-1995 to 0.12 (0.07-0.21)/100 PYFU in 2002-2003, and remained stable thereafter. After January 2001, 159 TB events were diagnosed; 65 cases in western Europe and 94 cases in eastern Europe; resulting in incidence rates of 0.12 (0.09-0.14) and 0.65 (0.52-0.79)/100 PYFU, respectively. In multivariable analysis, incidence rate of TB was approximately four-fold higher in eastern Europe compared with western Europe [incidence rate ratio (IRR) 4.25 (2.78-6.49), P < 0.001]. There were no significant temporal changes after 2001 and risk factors did not differ significantly between eastern Europe and western Europe. Lower CD4 cell counts, higher HIV-RNA levels, male sex, intravenous drug usage and African origin were all associated with higher risk of TB.

CONCLUSION

Incidence rates of TB in western Europe remained at a very low and stable level since 2001. After 2001, patients in eastern Europe were at substantially higher risk of TB than in western Europe. TB is of great concern in HIV-positive patients, especially in areas with high TB prevalence, high levels of immigration from TB-endemic regions, and with suboptimal access to combination antiretroviral therapy.

Incidence, risk factors and mortality of tuberculosis in Danish HIV patients 1995-2007

Background

Human Immunodeficiency Virus (HIV) infection predisposes to tuberculosis (TB). We described incidence, risk factors and prognosis of TB in HIV-1 infected patients during pre (1995-1996), early (1997-1999), and late Highly Active Antiretroviral Therapy (HAART) (2000-2007) periods.

Methods

We included patients from a population-based, multicenter, nationwide cohort. We calculated incidence rates (IRs) and mortality rates (MRs). Cox's regression analysis was used to estimate risk factors for TB infection with HAART initiation included as time updated variable. Kaplan-Meier was used to estimate mortality after TB.

Results

Among 2,668 patients identified, 120 patients developed TB during the follow-up period. The overall IR was 8.2 cases of TB/1,000 person-years of follow-up (PYR). IRs decreased during the pre-, early and late-HAART periods (37.1/1000 PYR, 12.9/1000 PYR and 6.5/1000 PYR respectively). African and Asian origin, low CD4 cell count and heterosexual and injection drug user route of HIV transmission were risk factors for TB and start of HAART reduced the risk substantially. The overall MR in TB patients was 34.4 deaths per 1,000 PYR (95% Confidence Interval: 22.0-54.0) and was highest in the first two years after the diagnosis of TB.

Conclusions

Incidence of TB still associated with conventional risk factors as country of birth, low CD4 count and route of HIV infection while HAART reduces the risk substantially. The mortality in this patient population is high in the first two years after TB diagnosis.

Tuberculosis in patients receiving antiretroviral treatment: incidence, risk factors, and prevention strategies

OBJECTIVE

To determine tuberculosis (TB) incidence rates and risk factors among individuals receiving antiretroviral treatment (ART).

DESIGN

Observational cohort in Johannesburg, South Africa.

METHODS

Incident TB was classified as early (less than 6 months of ART) or late (greater than 6 months of ART) incident TB. CD4 cell counts, viral load, body mass index, and hemoglobin were measured 6-monthly. Hazard ratios for factors associated with early and late incident TB were assessed using Cox proportional hazards regression.

RESULTS

During 13,416 person-years of follow-up, 501 TB cases occurred among 7536 individuals, corresponding to a 10% risk in the first 4 years of ART and an overall incidence rate of 4.2 cases/100 person-years. The highest incidence rate (21.7 per 100 person-years) was observed in the first 3 months of ART among people with CD4 count below 50 cells/mm3. Low baseline CD4 count, anemia, and low body mass index were the strongest risk factors for early incident TB. Low updated CD4 count, low updated body mass index, anemia, and high viral load on ART were strong risk factors for late incident TB.

CONCLUSIONS

Severity of HIV disease and unfavorable response to ART are associated with early and late incident TB, respectively. Early ART initiation and intensified TB screening at ART initiation are crucial to reduce incident TB.

Antiretroviral therapy for tuberculosis control in nine African countries

HIV has increased the incidence of tuberculosis (TB) by up to sevenfold in African countries, but antiretroviral therapy (ART) reduces the incidence of AIDS-related TB. We use a mathematical model to investigate the short-term and long-term impacts of ART on the incidence of TB, assuming that people are tested for HIV once a year, on average, and start ART at a fixed time after HIV seroconversion or at a fixed CD4(+) cell count. We fit the model to trend data on HIV prevalence and TB incidence in nine countries in sub-Saharan Africa. If HIV-positive people start ART within 5 y of seroconversion, the incidence of AIDS-related TB in 2015 will be reduced by 48% (range: 37-55%). Long-term reductions depend sensitively on the delay to starting ART. If treatment is started 5, 2, or 1 y after HIV seroconversion, or as soon as people test positive, the incidence in 2050 will be reduced by 66% (range: 57-80%), 95% (range: 93-96%), 97.7% (range: 96.9-98.2%) and 98.4% (range: 97.8-98.9%), respectively. In the countries considered here, early ART could avert 0.71 ± 0.36 [95% confidence interval (CI)] million of 3.4 million cases of TB between 2010 and 2015 and 5.8 ± 2.9 (95% CI) million of 15 million cases between 2015 and 2050. As more countries provide ART at higher CD4(+) cell counts, the impact on TB should be investigated to test the predictions of this model.

HIV-Associated Tuberculosis

The intersecting HIV and Tuberculosis epidemics in countries with a high disease burden of both infections pose many challenges and opportunities. For patients infected with HIV in high TB burden countries, the diagnosis of TB, ARV drug choices in treating HIV-TB coinfected patients, when to initiate ARV treatment in relation to TB treatment, managing immune reconstitution, minimising risk of getting infected with TB and/or managing recurrent TB, minimizing airborne transmission, and infection control are key issues. In addition, given the disproportionate burden of HIV in women in these settings, sexual reproductive health issues and particular high mortality rates associated with TB during pregnancy are important. The scaleup and resource allocation to access antiretroviral treatment in these high HIV and TB settings provide a unique opportunity to strengthen both services and impact positively in meeting Millennium Development Goal 6.

Assessment of mycobacteremia detection as a complementary method for the diagnosis of tuberculosis in HIV-infected patients

The purpose of this investigation was to assess the usefulness of mycobacteremia detection in human immunodeficiency virus (HIV) patients with suspected tuberculosis. The study included 47 patients with suspected tuberculosis and confirmed HIV infection. A first blood sample was incubated in a BACTEC 9050 MB system, while white blood cells isolation was performed on a second blood specimen before incubation in a BACTEC MGIT 960 system. The third specimen was taken from the affected organs of each patient according to their clinical profile. Twelve (25.5%) patients were positive for mycobacterial infection identified by any of the methods used. Ten (21.2%) were positive for Mycobacterium tuberculosis and 2 (4.3%) for M. avium. Six patients were diagnosed by the culture of specimen from affected organs only, whilst three other patients were positive exclusively for blood cultures. Three additional patients were diagnosed by both methods. Four patients with negative cultures were ultimately diagnosed with tuberculosis by measuring the adenosine deaminase levels. Mycobacteremia detection can be used to increase the sensitivity of the diagnosis of tuberculosis and other mycobacteria in patients with HIV. However, it cannot be used as the sole diagnostic method. Clinical specimen cultures do not provide 100% diagnostic accuracy and it is, therefore, critical to further improve the mycobacteria detection sensitivity.

Tuberculosis risk factors and mortality for HIV-infected persons receiving antiretroviral therapy in South Africa

OBJECTIVE

To determine important risk factors for and impact of tuberculosis on survival in HIV-infected patients starting antiretroviral therapy (ART) in South Africa.

DESIGN

Prospective trial of 1771 HIV-infected patients with either CD4 cell count less than 200 cells/microl or a prior AIDS-defining illness, enrolled in randomized trial of four antiretroviral regimens.

METHODS

Data collected from patient records.

RESULTS

A history of tuberculosis at study entry was reported by 27% of patients and correlated with poor baseline health status. A history of tuberculosis at baseline was associated with subsequent tuberculosis and death during ART, but was not itself an independent risk factor for poor outcome. Tuberculosis was diagnosed during ART in 14% of patients and was more frequent during the first 3 months. Tuberculosis during therapy was independently associated with increased hazard of other AIDS-defining events and death, regardless of when during ART tuberculosis occurred. ART that consistently suppressed circulating viremia reduced but did not eliminate tuberculosis risk.

CONCLUSION

In HIV-infected patients who started ART at low CD4 cell counts, tuberculosis at baseline was a predictor of death, but was not independent of other factors indicating poor baseline health status. Tuberculosis during follow-up was, in contrast, an independent predictor of death even after adjustments for baseline risk factors, including CD4 cell count and viral load. Virologic failure during ART was associated with a 55% increase in risk of tuberculosis. Thus, tuberculosis is a major marker for poor outcome both at baseline and during ART and is not completely eliminated by fully suppressive ART.

Antiretroviral therapy for control of the HIV-associated tuberculosis epidemic in resource-limited settings

Great progress has been made over the past few years in HIV testing in patients who have tuberculosis (TB) and in the scale-up of antiretroviral therapy. More than 3 million people in resource-limited settings were estimated to have started antiretroviral therapy by the end of 2007 and 2 million of these were in sub-Saharan Africa. However, little is known about what impact this massive public health intervention will have on the HIV-associated TB epidemic or how antiretroviral therapy might be used to best effect TB control. This article provides an in-depth review of these issues.

Dissemination of mycobacteria to the thymus renders newly generated T cells tolerant to the invading pathogen

The ability of the thymus to generate a population of T cells that is, for the most part, self-restricted and self-tolerant depends to a great extent on the Ags encountered during differentiation. We recently showed that mycobacteria disseminate to the thymus, which raised the questions of how mycobacteria within the thymus influence T cell differentiation and whether such an effect impacts host-pathogen interactions. Athymic nude mice were reconstituted with thymic grafts from Mycobacterium avium-infected or control noninfected donors. T cells generated from thymi of infected donors seemed generally normal, because they retained the ability to reconstitute the periphery and to respond to unspecific stimuli in vitro as well as to antigenic stimulation with third-party Ags, such as OVA, upon in vivo immunization. However, these cells were unable to mount a protective immune response against a challenge with M. avium. The observation that thymic infection interferes with T cell differentiation, generating T cells that are tolerant to pathogen-specific Ags, is of relevance to understand the immune response during chronic persistent infections. In addition, it has potential implications for the repertoire of T cells generated in patients with a mycobacterial infection recovering from severe lymphopenia, such as patients coinfected with HIV and receiving antiretroviral therapy.

Mortality from HIV and TB coinfections is higher in Eastern Europe than in Western Europe and Argentina

BACKGROUND AND OBJECTIVES

Tuberculosis (TB) is a leading cause of death in HIV-infected patients worldwide. We aimed to study clinical characteristics and outcome of 1075 consecutive patients diagnosed with HIV/TB from 2004 to 2006 in Europe and Argentina.

METHODS

One-year mortality was assessed in patients stratified according to region of residence, and factors associated with death were evaluated in multivariable Cox models.

RESULTS

At TB diagnosis, patients in Eastern Europe had less advanced immunodeficiency, whereas a greater proportion had a history of intravenous drug use, coinfection with hepatitis C, disseminated TB, and infection with drug-resistant TB (P < 0.0001). In Eastern Europe, fewer patients initiated TB treatment containing at least rifamycin, isoniazid, and pyrazinamide or combination antiretroviral therapy (P < 0.0001). Mortality at 1 year was 27% in Eastern Europe, compared with 7, 9 and 11% in Central/Northern Europe, Southern Europe, and Argentina, respectively (P < 0.0001). In a multivariable model, the adjusted relative hazard of death was significantly lower in each of the other regions compared with Eastern Europe: 0.34 (95% confidence interval 0.17-0.65), 0.28 (0.14-0.57), 0.34 (0.15-0.77) in Argentina, Southern Europe and Central/Northern Europe, respectively. Factors significantly associated with increased mortality were CD4 cell count less than 200 cells/microl [2.31 (1.56-3.45)], prior AIDS [1.74 (1.22-2.47)], disseminated TB [2.00 (1.38-2.85)], initiation of TB treatment not including rifamycin, isoniazid and pyrazinamide [1.68 (1.20-2.36)], and rifamycin resistance [2.10 (1.29-3.41)]. Adjusting for these known confounders did not explain the increased mortality seen in Eastern Europe.

CONCLUSION

The poor outcome of patients with HIV/TB in Eastern Europe deserves further study and urgent public health attention.

Short-term and long-term risk of tuberculosis associated with CD4 cell recovery during antiretroviral therapy in South Africa

OBJECTIVE

To determine the short-term and long-term risks of tuberculosis (TB) associated with CD4 cell recovery during antiretroviral therapy (ART).

DESIGN

Observational community-based ART cohort in South Africa.

METHODS

TB incidence was determined among patients (n = 1480) receiving ART for up to 4.5 years in a South African community-based service. Updated CD4 cell counts were measured 4-monthly. Person-time accrued within a range of CD4 cell count strata (CD4 cell strata) was calculated and used to derive CD4 cell-stratified TB rates. Factors associated with incident TB were identified using Poisson regression models.

RESULTS

Two hundred and three cases of TB were diagnosed during 2785 person-years of observation (overall incidence, 7.3 cases/100 person-years). During person-time accrued within CD4 cell strata 0-100, 101-200, 201-300, 301-400, 401-500 and more than 500 cells/microl unadjusted TB incidence rates were 16.8, 9.3, 5.5, 4.6, 4.2 and 1.5 cases/100 person-years, respectively (P < 0.001). During early ART (first 4 months), adjusted TB rates among those with CD4 cell counts 0-200 cells/microl were 1.7-fold higher than during long-term ART (P = 0.026). Updated CD4 cell counts were the only patient characteristic independently associated with long-term TB risk.

CONCLUSION

Updated CD4 cell counts were the dominant predictor of TB risk during ART in this low-resource setting. Among those with baseline CD4 cell counts less than 200 cells/microl, the excess adjusted risk of TB during early ART was consistent with 'unmasking' of disease missed at baseline screening. TB incidence rates at CD4 cell counts of 200-500 cells/microl remained high and adjunctive interventions are required. TB prevention would be improved by ART policies that minimized the time patients spend with CD4 cell counts below a threshold of 500 cells/microl.

Dissection of regenerating T-Cell responses against tuberculosis in HIV-infected adults sensitized by Mycobacterium tuberculosis

RATIONALE

Combination antiretroviral treatment (cART) reduces the risk of tuberculosis in HIV-infected people. Therefore a novel approach to gain insight into protection against tuberculosis is to analyze the T cells that expand in people sensitized by Mycobacterium tuberculosis (MTB) during cART.

OBJECTIVES

To longitudinally analyze CD4 T-cell subsets during the first year of cART, from the time of starting cART (Day 0), in 19 HIV-infected, MTB-sensitized adults.

METHODS

Peripheral blood mononuclear cells were obtained on Day 0, Weeks 2, 4, 12, 24, 36, and 48 of cART and were stimulated with purified protein derivative (PPD) followed by flow cytometry to analyze surface markers and intracellular cytokines.

MEASUREMENTS AND MAIN RESULTS

CD4(+) T cells significantly increased during follow-up and the viral load fell to undetectable levels in each patient, indicating successful immune restoration. Central memory CD27(+)CD45RA(-) and CD27(+)CCR5(-) CD4(+) cells expanded by 12 weeks (P < 0.02) followed by naive CD27(+)CD45RA(+) cells at 36 weeks (P = 0.02). Terminally differentiated effector CD4(+)CD27(-)CCR7(-) cells decreased by 12 weeks (P = 0.02), paralleled by a proportional decline of PPD-specific CD4(+)IFN-gamma(+) cells (P = 0.02). However, the absolute numbers of PPD-specific IFN-gamma-producing cells, determined by enzyme-linked immunospot assay, increased (P = 0.02).

CONCLUSIONS

Rapid effector responses are often measured when evaluating immunity. We show that although cART is associated with an absolute increase in effector function, the proportional response decreased and the strongest correlate of increased cART-mediated immunity in this study was the central memory response.

Cost-effectiveness analysis of raltegravir in treatment-experienced HIV type 1-infected patients in Spain

Raltegravir, a novel HIV-1 integrase inhibitor, has superior efficacy with optimized background treatment (OBT) vs. placebo + OBT in treatment-experienced HIV-1 patients. This study assessed the long-term cost effectiveness of raltegravir from a Spanish National Healthcare System perspective. A cohort-state-transition model was used to estimate clinical and economic outcomes associated with raltegravir + OBT vs. OBT alone. Subjects were stratified into health states according to HIV RNA level, CD4 count, and opportunistic infection (OI) history, and could transition into different health states over time based on projected long-term efficacy. Each health state was associated with a distinct treatment cost and utility (QoL) score. Model inputs for mortality, resource utilization, unit costs, OI risk, and long-term durability of viral suppression were obtained from clinical trials, published studies, and database analyses. Model outcomes were reported as incremental cost-effectiveness ratios (ICERs) in 2007 Euros per quality-adjusted life-year (euro/QALY) gained. Costs and QALYs were discounted at 6% per year based on Spanish cost-effectiveness guidelines. Extensive sensitivity analyses were conducted. Five years of treatment with raltegravir + OBT resulted in an additional 4.5 years of undiscounted life expectancy vs. OBT alone. The ICER of raltegravir + OBT vs. OBT alone was euro22,908/QALY and euro31,431/QALY for 3- and 5-year use, respectively. Lower ICERs were observed with lower discount rates (3%) for costs and benefits, lower raltegravir price (20%), and shorter treatment duration (3 years). ICER was also sensitive to analytical time horizon and alternative sources of QoL scores. In treatment-experienced Spanish patients, raltegravir was projected to provide survival benefits and be cost effective.

Tuberculosis incidence and risk factors among patients living with HIV/AIDS in public health service institutions in Brasilia, Federal District

In order to estimate the incidence of and risk factors for developing tuberculosis, the clinical charts of a retrospective cohort of 281 HIV-positive adults, who were notified to the AIDS Program of the Health Department of Brasilia in 1998, were reviewed in 2003. All the patients were treatment-naive regarding antiretroviral therapy at the time of inclusion in the cohort. Twenty-nine patients were identified as having tuberculosis at the start of the study. Thirteen incident tuberculosis cases were identified during the 60 months of follow-up, with an incidence density rate of 1.24/100 person-years. Tuberculosis incidence was highest among patients with baseline CD4+ T-lymphocyte counts < or = 200 cells/microl who were not using antiretroviral therapy (incidence = 5.47; 95% CI = 2.73 to 10.94). Multivariate analysis showed that baseline CD4+ T-lymphocyte counts < or = 200 cells/microl (adjusted hazard ratio [AHR] = 5.09; 95% CI = 1.27 to 20.37; p = 0.02) and non-use of antiretroviral therapy (AHR = 12.17; 95% CI = 2.6 to 56.90; p = 0.001) were independently associated with increased risk of tuberculosis.

Risk and prognostic significance of tuberculosis in patients from The TREAT Asia HIV Observational Database

Background

To assess the risk and the prognostic significance of tuberculosis (TB) diagnosis in patients from The TREAT Asia HIV Observational Database, a multi-centre prospective cohort of HIV-infected patients receiving HIV care in the Asia-Pacific region.

Methods

The risk of TB diagnosis after recruitment was assessed in patients with prospective follow-up. TB diagnosis was fitted as a time-dependent variable in assessing overall survival.

Results

At baseline, 22% of patients were diagnosed with TB. TB incidence was 1.98 per 100 person-years during follow up, with predictors including younger age, lower recent CD4 count, duration of antiretroviral treatment, and living in high TB burden countries. Among 3279 patients during 6968 person-years, 142 died (2.04 per 100 person-years). Compared to patients with CDC category A or B illness only, mortality was marginally higher in patients with single Non-TB AIDS defining illness (ADI), or TB only (adjusted HR 1.35, p = 0.173) and highest in patients with multiple non-TB AIDS or both TB and other ADI (adjusted HR 2.21, p < 0.001).

Conclusion

The risk of TB diagnosis was associated with increasing immunodeficiency and partly reduced by antiretroviral treatment. The prognosis of developing TB appeared to be similar to that following a diagnosis of other non-TB ADI.

Changing global epidemiology of pulmonary manifestations of HIV/AIDS

Tremendous advances have occurred in the care of patients with HIV/AIDS resulting from the advent of highly active antiretroviral therapy (HAART). This has led to differences in the presentations of HIV-related pulmonary disease. Infections such as bacterial pneumonias, particularly Streptococcus pneumoniae, remain commonplace, while opportunistic agents such as Pneumocystis jirovecii remain a concern in patients without adequate access to optimal medical care. The tuberculosis epidemic, once thought to be slowing, has been re-energized by the spread of HIV, particularly in sub-Saharan Africa. Unusual inflammatory responses due to a phenomenon of immune reconstitution, are now recognized as a consequence of HAART, with a reported incidence of IRIS in this setting ranges from 7 to 45% in retrospective reviews. Noninfectious pulmonary conditions such as chronic obstructive lung disease and pulmonary malignancies are gaining prominence as patients are accessing antiretroviral care and enjoying significantly extended survival.

Immune reconstitution and "unmasking" of tuberculosis during antiretroviral therapy

Tuberculosis (TB) is the most common opportunistic disease in HIV-infected patients during the initial months of antiretroviral therapy (ART) and presents a great challenge to ART programs in resource-limited settings. The mechanisms underlying development of TB in this period are complex. Some cases may represent progression of undiagnosed subclinical disease present before starting ART, emphasizing the importance of careful screening strategies for TB. It has been suggested that progression in such cases is due to immune reconstitution disease-a phenomenon in which dysregulated restoration of pathogen-specific immune responses triggers the presentation of subclinical disease. However, whereas some cases have exaggerated or overtly inflammatory manifestations consistent with existing case definitions for IRD, many others do not. Moreover, since ART-induced immune recovery is a time-dependent process, active TB may develop as a consequence of persisting immunodeficiency. All these mechanisms are likely to be important, representing a spectrum of complex interactions between mycobacterial burden and changing host immune response. We propose that the potential range of effects of ART includes (1) shortening of the time for subclinical TB to become symptomatic (a phenomenon often referred to as "unmasking"), (2) increased rapidity of initial onset of TB symptoms, and (3) heightened intensity of clinical manifestations. We suggest that the term "ART-associated TB" be used to refer collectively to all cases of TB presenting during ART and that "immune reconstitution disease" be used to refer to the subset of ART-associated TB cases in which the effect on disease severity results in exaggerated and overtly inflammatory disease.

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.

HIV-Related Lung Disorders

Highly active antiretroviral therapy (HAART) has dramatically altered the spectrum of morbidity and mortality in HIV-infected patients. This has been attributed to improvements in the lung microenvironment leading to enhanced pulmonary immunity, either by preventing the progressive loss of immune function or by actually promoting immune restoration. However, these changes have been accompanied by the recognition of new pulmonary complications in HIV-infected subjects, especially those associated with immune reconstitution. In this review we will describe how HIV infection alters the normal pulmonary environment, highlight the effect of HAART on these perturbations, and discuss potential complications of HAART in the lung, focusing on the pulmonary immune reconstitution inflammatory syndrome.

Life and death in the granuloma: immunopathology of tuberculosis

During tuberculosis (TB) infection, the granuloma provides the microenvironment in which antigen-specific T cells colocate with and activate infected macrophages to inhibit the growth of Mycobacterium tuberculosis. Although the granuloma is the site for mycobacterial killing, virulent mycobacteria have developed a variety of mechanisms to resist this macrophage-mediated killing. These surviving mycobacteria become dormant, however, if host cellular immunity or the signals maintaining granuloma structure wane, or if mycobacteria resume replication, leading to reactivation of TB. This balance of life and death applies not only to the mycobacterium but also to the host macrophages that may undergo apoptosis or necrosis, leading to the characteristic caseous necrosis within the granuloma, and the potential spread of TB infection. The immunological factors controlling the development and maintenance of the granuloma will be reviewed.

Management of patients with HIV in the intensive care unit

Because there are more than one million Americans with HIV, intensive care units continue to see frequent patients with HIV infection. In the era of highly active antiretroviral therapy, clinicians must be aware of drug toxicities and drug interactions. They must also recognize traditional opportunistic infections, as well as newer syndromes such as immune reconstitution syndrome, multicentric Castleman's disease, and primary pleural cell lymphoma.

Tuberculosis after HAART initiation in HIV-positive patients from five countries with a high tuberculosis burden

BACKGROUND

HAART reduces tuberculosis (TB) incidence in people living with HIV/AIDS but those starting HAART may develop active TB or subclinical TB may become apparent in the immune reconstitution inflammatory syndrome.

OBJECTIVE

To measure the incidence rate of notified TB in people receiving HAART in five HIV programmes occurring in low-resource countries with a high TB/HIV burden.

METHODS

A retrospective review in five Médecins Sans Frontières programmes (Cambodia, Thailand, Kenya, Malawi and Cameroon) allowed incidence rates of notified TB to be calculated based on follow-up time after HAART initiation.

RESULT

Among 3151 patients analysed, 90% had a CD4 cell count of < 200 cells/mul. Median follow-up time ranged from 3.7 months in Thailand or Kenya to 11.1 months in Cambodia. Incidence rates were 7.6, 10.4, 17.6, 14.3 and 4.8/100 person-years for pulmonary TB and 12.7, 4.3, 6.9, 2.1 and 0/100 person-years for extra-pulmonary TB in the programmes in Cambodia, Thailand, Kenya, Malawi and Cameroon, respectively. Overall, 62.3% of pulmonary TB and 54.9% of extra-pulmonary TB were diagnosed within 3 months after HAART initiation.

CONCLUSION

High incidence rates of notified TB under HAART in programmes held in poor-resource countries were observed; these were likely to include both undiagnosed prevalent TB at HAART initiation and subclinical TB developing during the immune reconstitution inflammatory syndrome. This raises operational issues concerning TB diagnosis and treatment of TB/HIV-coinfected patients and prompts for urgent TB and HIV care integration.

Reconstitution of antimycobacterial immune responses in HIV-infected children receiving HAART

OBJECTIVE

Recent epidemiological studies in adults suggest that HAART can prevent the development of tuberculosis in HIV-infected individuals, but the mechanisms are incompletely understood and no data exist in children. We investigated whether changes in mycobacterial-specific immune responses can be demonstrated in children after commencing antiretroviral therapy.

DESIGN

We measured mycobacterial growth in vitro using a novel whole-blood assay employing reporter-gene tagged bacillus Calmette-Guérin (BCG) in a prospective cohort study in the tuberculosis-endemic environment of South Africa. Key cytokines were measured in supernatants collected from the whole-blood assay using cytometric bead array.

PATIENTS

A cohort of 15 BCG-vaccinated HIV-infected children was evaluated prospectively for in-vitro antimycobacterial immune responses before and during the first year of HAART. All children had advanced HIV disease. Nine children completed all study timepoints.

RESULTS

Before HAART, blood from children showed limited ability to restrict the growth of mycobacteria in the functional whole-blood assay. The introduction of HAART was followed by rapid and sustained reconstitution of specific antimycobacterial immune responses, measured as the decreased growth of mycobacteria. IFN-gamma levels in culture supernatants did not reflect this response; however, a decline in TNF-alpha was observed.

CONCLUSION

This is the first study using a functional in-vitro assay to assess the effect of HAART on immune responses to mycobacteria in HIV-infected children. Our in-vitro data mirror the in-vivo observation of decreased susceptibility to tuberculosis in HIV-infected adults receiving antiretroviral agents. This model may be useful for further characterizing immune reconstitution after HAART.