Incidence of tuberculosis in the United States among HIV-infected persons. The Pulmonary Complications of HIV Infection Study Group

Human Immunodeficiency Virus and Uveitis

Uveitis is one of the most common ocular complications in people living with the Human immunodeficiency virus (HIV) and can be classified into HIV-induced uveitis, co-infection related uveitis, immune recovery uveitis, and drug-induced uveitis. The introduction of antiretroviral therapy has considerably changed the incidence, diagnosis, and treatment of different types of HIV-related uveitis. Furthermore, the specific immune condition of patients infected with HIV makes diagnosing HIV-related uveitis difficult. Recent studies have focused on the growing prevalence of syphilis/tuberculosis co-infection in uveitis. Simultaneously, more studies have demonstrated that HIV can directly contribute to the incidence of uveitis. However, the detailed mechanism has not been studied. Immune recovery uveitis is diagnosed by exclusion, and recent studies have addressed the role of biomarkers in its diagnosis. This review highlights recent updates on HIV-related uveitis. Furthermore, it aims to draw the attention of infectious disease physicians and ophthalmologists to the ocular health of patients infected with HIV.

Incidence and predictors of Tuberculosis among patients enrolled in Anti-Retroviral Therapy after universal test and treat program, Addis Ababa, Ethiopia. A retrospective follow -up study

Introduction

Tuberculosis (TB) is the leading killer of people living with HIV (PLHIV) and almost one-third of deaths in the world are attributed to it and many of these deaths occur in developing countries. Despite these evidences, after the implementation of universal test and treat (UTT) strategy, information regarding the incidence and predictors of tuberculosis among PLHIV is limited in Ethiopia. Therefore, this study aimed to assess the incidence and predictors of tuberculosis among patients enrolled in Anti-Retroviral Therapy (ART) after universal test and treat program at St. Peter hospital and Zewditu Memorial Hospital, Addis Ababa, Ethiopia.

Methods

Institutional-based retrospective cohort study was conducted from November 1 to 30, 2020. Simple random sampling was used to select a total of 539 adults records which was enrolled on ART. Data was collected and entered into EPI DATA 3.1 and analyzed using STATA version 14.1. Time-to-event distributions were estimated using Kaplan–Meier estimates. Hazards across different categories were compared using log-rank tests. Predictors were identified using the Cox proportional hazards model. The hazard ratio (HR) and 95% confidence interval (CI) were computed. Variables having P-value < 0.05 from the multivariable analysis were considered as a statistically significant.

Result

Among 539 records reviewed, 529 (98%) were included in the final analysis. The total follow-up period was 1529 Person-Year (PY). The incidence rate in this cohort was found to be 4.84 per 100-person year (95%CI,3.83–6.11). CD4 count<200 (AHR: 3.14,95% CI:1.64–7.10), poor adherence (AHR:2.16, 95% CI:1.21–3.85), underweight (AHR:2.42, 95% CI: 1.30–4.51), not taking isoniazid prophylaxis therapy (AHR: 2.78,95% CI: 1.06–7.30), being bedridden 3.06; (AHR: 3.06, 95% CI: 1.50–6.24), and baseline WHO stage three or four (AHR:2.33, 95% CI:1.08–5.02) were independent predictors for the incidence of TB among HIV positive patients.

Conclusion

In this study, the incidence of tuberculosis is relatively low as compared to studies done before the initiation of test and treat program in Ethiopia. low CD4count, poor level of adherence, low BMI, not taking IPT prophylaxis, bedridden functional status, and being on baseline WHO stage III or IV were found to increase the hazard of tuberculosis. Hence, close follow up, reminders, surveillance, and tracing mechanisms targeting this higher risk group would decrease Tuberculosis among PLHIV.

Diagnostic Value of Interferon-Gamma Release Assays for Tuberculosis in the Immunocompromised Population

Interferon-gamma release assays (IGRAs) are widely used in the diagnosis of Mycobacterium tuberculosis (M. tuberculosis) infection by detecting interferon-γ released by previously sensitized T-cells in-vitro. Currently, there are two assays based on either enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISPOT) technology, with several generations of products available. The diagnostic value of IGRAs in the immunocompromised population is significantly different from that in the immunocompetent population because their results are strongly affected by the host immune function. Both physiological and pathological factors can lead to an immunocompromised situation. We summarized the diagnostic value and clinical recommendations of IGRAs for different immunocompromised populations, including peoplewith physiological factors (pregnant and puerperal women, children, and older people), as well as people with pathological factors (solid organ transplantation recipients, combination with human immunodeficiency virus infection, diabetes mellitus, end-stage renal disease, end-stage liver disease, and chronic immune-mediated inflammatory diseases). Though the performance of IGRAs is not perfect and often requires a combination with other diagnostic strategies, it still has some value in the immunocompromised population. Hopefully, the newly developed IGRAs could better target this population.

Infectious Diseases Learning Unit: Understanding Advances in the Treatment of Latent Tuberculosis Infection Among People With Human Immunodeficiency Virus

Tuberculosis (TB) remains the leading cause of death among people with human immunodeficiency virus (PWH). The diagnosis of latent TB infection (LTBI) and treatment with TB preventative therapy (TPT) can reduce morbidity and mortality in this population. Historically, isoniazid has been recommended for TPT in PWH due to the absence of drug-drug interactions with most antiretroviral therapy (ART). However, newer rifamycin-based regimens are safer, shorter in duration, associated with improved adherence, and may be as or more effective than isoniazid TPT. Current guidelines have significant heterogeneity in their recommendations for TPT regimens and acceptability of drug interactions with modern ART. In this Infectious Diseases learning unit, we review common questions on diagnosis, treatment, and drug interactions related to the management of LTBI among PWH.

Impact of Aging and HIV Infection on the Function of the C-Type Lectin Receptor MINCLE in Monocytes

Both aging and HIV infection are associated with an enhanced pro-inflammatory environment that contributes to impaired immune responses and is mediated in part by innate immune pattern-recognition receptors. MINCLE is a C-type lectin receptor that recognizes trehalose-6,6'-dimycolate or "cord factor," the most abundant glycolipid in Mycobacterium tuberculosis. Here, we evaluated MINCLE function in monocytes in a cohort of HIV-infected and uninfected young (21-35 years) and older adults (≥60 years) via stimulation of peripheral blood mononuclear cells with trehalose-6,6-dibehenate, a synthetic analog of trehalose-6,6'-dimycolate and measurement of cytokine production (interleukin [IL]-10, IL-12, IL-6, tumor necrosis factor-α) by multicolor flow cytometry. Our studies show an age- and HIV-associated increase in cytokine multifunctionality of monocytes both at the population and single cell level that was dominated by IL-12, IL-10, and IL-6. These findings provide insight into the host response to M. tuberculosis and possible sources for the pro-inflammatory environment seen in aging and HIV infection.

High tuberculosis burden among HIV-infected populations in Thailand due to a low-sensitivity tuberculin skin test

The current Thai guideline recommends that among people living with HIV, isoniazid preventive therapy (IPT) should be given to those with a positive tuberculin skin test (TST). We conducted a case-control study, nested within a cohort study, in Chiang Rai Province in Thailand to determine the role of TST in predicting the development of active tuberculosis (TB) within the following 2 years. Comparison between participants with CD4+ counts <50cells/mm³ to those with CD4+ ≥200cells/mm³ revealed that TST results were less sensitive (7.7% vs 50.0%) and had a lower negative predictive value (73.1% vs 97.3%) in those with a CD4+ count <50cells/mm³. In people with HIV, using a positive TST result as a criterion for initiating IPT inadvertently decreases the benefits of IPT, especially among those with low CD4+ counts.

The optimization of methadone dosing whilst treating with rifampicin: A pharmacokinetic modeling study

BACKGROUND

The use of oral methadone in opioid substitution treatment (OST) for the management of opioid use disorder is established clinical practice. Confounding treatment is the increased risks of contracting Mycobacterium tuberculosis, the mainstay treatment of which incorporates the potent CYP 2B6 inducer rifampicin.

METHODS

This study applied pharmacokinetic modelling using virtual clinical trials, to pharmacokinetically quantify the extent and impact of rifampicin-mediated drug-drug interactions (DDI) on methadone plasma concentrations. An R-methadone model was developed and validated against 11 retrospective clinical studies prior to use in all subsequent studies. The aims were to investigate: (i) the impact of the DDI on daily methadone doses of 60 mg, 90 mg and 120 mg; (ii) dose escalation during rifampicin and (iii) dose reduction following rifampicin cessation.

RESULTS

A dose increase to 160 mg daily during rifampicin treatment phases was required to maintain peak methadone plasma concentrations within a derived therapeutic window of 80-700 ng/mL. Dose escalation prior to rifampicin initiation was not required and resulted in an increase in subjects with supra-therapeutic concentrations. However, during rifampicin cessation, a dose reduction of 10 mg every 2 days commencing prior to rifampicin cessation, ensured that most patients possessed a peak methadone plasma concentration within an optimal therapeutic window.

IMPLICATIONS

Rifampicin significantly alters methadone plasma concentrations and necessitates dose adjustments. Daily doses of almost double those used perhaps more commonly in clinical practice are required for optimal plasma concentration and careful consideration of dose reduction strategies would be required during the deinduction phase.

Screening for Latent Tuberculosis Infection Among HIV-Infected Medicaid Enrollees

OBJECTIVES

In the United States, universal screening for latent tuberculosis (TB) infection among people with HIV is recommended, but the percentage receiving screening is unknown. This study assessed screening for latent TB infection among people with HIV enrolled in Medicaid during 2006-2010.

METHODS

We used nationwide fee-for-service Medicaid records to identify people with HIV, measure screening for latent TB infection, and examine associated demographic, social, and clinical factors. We used logistic regression analysis to calculate odds ratios (ORs) and 95% confidence intervals (CIs). We created 2 multivariate models to prevent collinearity between variables for length of HIV infection.

RESULTS

Of 152 831 people with HIV, 26 239 (17.2%) were screened for latent TB infection. The factor most strongly associated with screening was TB exposure or suspected TB (OR = 3.78; 95% CI, 3.27-4.37). Significant demographic characteristics associated with screening included being African American (OR = 1.28; 95% CI, 1.24-1.32) or ≤20 years of age (OR = 1.35; 95% CI, 1.28-1.42). Significant clinical and social factors associated with screening included poor housing conditions, low body mass index, chemotherapy treatment, and use of certain substances (ORs ranged from 1.24 [95% CI, 1.20-1.27] to 1.47 [95% CI, 1.22-1.76]). The screening rate for latent TB infection was higher among people with newly diagnosed HIV infection than among those with established infection (OR = 1.37; 95% CI, 1.32-1.41) and among people with a longer established HIV infection than among those with shorter HIV infection (OR = 1.24; 95% CI, 1.23-1.26 for each additional year).

CONCLUSION

Screening for latent TB infection among fee-for-service Medicaid beneficiaries with HIV was suboptimal, despite the presence of demographic, social, or clinical characteristics that should have increased the likelihood of screening. The lack of certain data in Medicaid may have resulted in an underestimation of screening.

CD4 count and tuberculosis risk in HIV-positive adults not on ART: a systematic review and meta-analysis

Background

CD4 cell count in adults with human immunodeficiency virus (HIV) infection (PLHIV) not receiving antiretroviral therapy (ART) influences tuberculosis (TB) risk. Despite widespread use in models informing resource allocation, this relationship has not been systematically reviewed.

Methods

We systematically searched MEDLINE, Aidsinfo, Cochrane review database and Google Scholar for reports in English describing TB incidence stratified by updated CD4 cell count in cohorts of HIV-positive adults (age ≥15 years) not on ART (PROSPERO protocol no: CRD42016048888). Among inclusion criteria were: reporting precision for TB incidence, repeated CD4 measurements, and TB incidence reported for those not on ART or monotherapy. Study quality was assessed via the Newcastle-Ottawa tool for cohort studies. A Bayesian hierarchical model was fitted to estimate the pooled factor increase in TB incidence with respect to CD4 cell count decrement.

Results

A total of 1,555 distinct records were identified from which 164 full text articles were obtained. Common reasons for exclusion of full texts were: no valid TB incidence, no repeat CD4 measurements, and not reporting TB incidence by ART status. The seven studies included reported on 1,206 TB cases among 41,271 individuals, with a typical median follow-up of four years. Studies were generally rated as moderate or high quality. Our meta-analysis estimated a 1.43 (95% credible interval: 1.16–1.88)-fold increase in TB incidence per 100 cells per mm³ decrease in CD4 cell count.

Discussion

Our analysis confirms previous estimates of exponential increase in TB incidence with declining CD4 cell count in adults, emphasizing the importance of early ART initiation to reduce TB risk in PLHIV.

Effect of Pregnancy on Interferon Gamma Release Assay and Tuberculin Skin Test Detection of Latent TB Infection Among HIV-Infected Women in a High Burden Setting

BACKGROUND

Peripartum immunologic changes may affect latent tuberculosis infection (LTBI) diagnostic performance among HIV-infected women.

METHODS

HIV-infected women were serially tested with tuberculin skin test (TST) and interferon gamma release assay [QuantiFERON TB Gold In-tube (QFT)] in pregnancy and 6 weeks postpartum in Kenya. Prevalence, sensitivity and agreement, and correlates of QFT/TST positivity were assessed. Quantitative QFT mitogen and Mycobacterium tuberculosis antigen (Mtb-Ag) responses were compared by peripartum stage. Incidence of test conversion at 6 weeks postpartum was evaluated in baseline TST-/QFT- women.

RESULTS

Among 100 HIV-infected women, median age was 26 years, median CD4 was 555 cells per cubic millimeter, and 88% were on antiretrovirals. More women were QFT+ than TST+ in both pregnancy (35.4% vs. 13.5%, P = 0.001) and postpartum (29.6% vs. 14.8%, P < 0.001). Among 18 consistently QFT+ women, 8 (44%) converted from TST- to TST+, with improved test agreement postpartum (56.9%, κ = 0.20 to 82.4%, κ = 0.60). Three initially QFT-/TST- women had test conversion (TST+ and/or QFT+), suggesting new infection (incidence 13.4/100 person-years). Mean QFT mitogen (4.46 vs. 7.64 IU/mL, P < 0.001) and Mtb-Ag (1.03 vs. 1.54 IU/mL, P = 0.03) responses were lower among all women retested in pregnancy vs. postpartum, and specifically among persistently QFT+ women (Mtb-Ag: 3.46 vs. 4.48 IU/mL, P = 0.007). QFT indeterminate rate was higher in pregnancy (16%) compared with postpartum (0%) because of lower mitogen response.

CONCLUSIONS

QFT identified >2-fold more women with LTBI compared with TST in pregnancy and postpartum. Lower QFT Mtb-Ag and mitogen responses in pregnancy compared with postpartum suggest that pregnancy-associated immunologic changes may influence LTBI test performance.

Three months of weekly rifapentine and isoniazid for treatment of Mycobacterium tuberculosis infection in HIV-coinfected persons

OBJECTIVE

Compare the effectiveness, tolerability, and safety of 3 months of weekly rifapentine and isoniazid under direct observation (3HP) versus 9 months of daily isoniazid (9H) in HIV-infected persons.

DESIGN

Prospective, randomized, and open-label noninferiority trial.

SETTING

The United States , Brazil, Spain, Peru, Canada, and Hong Kong.

PARTICIPANTS

HIV-infected persons who were tuberculin skin test positive or close contacts of tuberculosis cases.

INTERVENTION

3HP versus 9H.

MAIN OUTCOME MEASURES

The effectiveness endpoint was tuberculosis; the noninferiority margin was 0.75%. The tolerability endpoint was treatment completion; the safety endpoint was drug discontinuation because of adverse drug reaction.

RESULTS

Median baseline CD4 cell counts were 495 (IQR 389-675) and 538 (IQR 418-729) cells/μl in the 3HP and 9H arms, respectively (P = 0.09). In the modified intention-to-treat analysis, there were two tuberculosis cases among 206 persons [517 person-years (p-y) of follow-up] in the 3HP arm (0.39 per 100 p-y) and six tuberculosis cases among 193 persons (481 p-y of follow-up) in the 9H arm (1.25 per 100 p-y). Cumulative tuberculosis rates were 1.01 versus 3.50% in the 3HP and 9H arms, respectively (rate difference: -2.49%; upper bound of the 95% confidence interval of the difference: 0.60%). Treatment completion was higher with 3HP (89%) than 9H (64%) (P < 0.001), and drug discontinuation because of an adverse drug reaction was similar (3 vs. 4%; P = 0.79) in 3HP and 9H, respectively.

CONCLUSION

Among HIV-infected persons with median CD4 cell count of approximately 500 cells/μl, 3HP was as effective and safe for treatment of latent Mycobacterium tuberculosis infection as 9H, and better tolerated.

Occupational Risk Factors for Tuberculosis Among Healthcare Workers in KwaZulu-Natal, South Africa

BACKGROUND

Tuberculosis is a known occupational hazard for healthcare workers (HCWs), especially in countries with a high burden of tuberculosis. It is estimated that HCWs have a 2- to 3-fold increased risk of developing tuberculosis compared with the general population. The objective of this study was to identify occupational risk factors for tuberculosis among HCWs in 3 district hospitals with specialized multidrug-resistant tuberculosis wards in KwaZulu-Natal, South Africa.

METHODS

We conducted a case-control study of HCWs diagnosed with tuberculosis between January 2006 and December 2010. Cases and controls were asked to complete a self-administered questionnaire regarding potential risk factors for tuberculosis.

RESULTS

Of 307 subjects selected, 145 (47%) HCWs responded to the questionnaire; 54 (37%) tuberculosis cases and 91 (63%) controls. Cases occurred more frequently among clinical staff 46% (n = 25) and support staff 35% (n = 19). Thirty-two (26% [32/125]) HCWs were known to be infected with human immunodeficiency virus (HIV), including 45% (21/54) of cases. HCWs living with HIV (odds ratio [OR], 6.35; 95% confidence interval [CI], 3.54-11.37) and those who spent time working in areas with patients (OR, 2.24; 95% CI, 1.40-3.59) had significantly greater odds of developing tuberculosis, controlling for occupation, number of wards worked in, and household crowding.

CONCLUSIONS

HIV was the major independent risk factor for tuberculosis among HCWs in this sample. These findings support the need for HCWs to know their HIV status, and for HIV-infected HCWs to be offered antiretroviral therapy and isoniazid preventive therapy. Infection prevention and control should also be improved to prevent transmission of tuberculosis in healthcare settings to protect both HCWs and patients.

Interferon-Gamma Release Assays for the Diagnosis of Tuberculosis: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

We conducted a systematic review and meta-analysis to compare the accuracy of the interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST) for the diagnosis of Mycobacterium tuberculosis infection.

METHODS

We systematically searched PubMed, Embase, Cochrane library, and Web of Science databases for relevant published studies in recent decades and calculated pooled estimated sensitivities, specificities, DOR, and SROC curve of the QFT-IT, T-SPOT and TST. Random-effects models were used to assess estimates from studies with significant heterogeneity. Moreover, area under the curve was used to evaluate the accuracy of the tests.

RESULTS

Overall, 9 studies for QFT-IT, 12 studies for T-SPOT, and 16 studies for TST involving 3586 participants were included in this analysis. We found that sensitivities of the QFT-IT, T-SPOT, and TST were respectively 0.842 (95 % CI 0.811-0.870), 0.840 (95 % CI 0.814-0.864), and 0.665 (CI 0.635-0.693); specificities were respectively 0.745 (95 % CI 0.715-0.775), 0.658 (95 % CI 0.621-0.693), and 0.633 (CI 0.605-0.661); positive likelihood ratios were respectively 3.652 (95 % CI 2.180-6.117), 2.196 (95 % CI 1.727-2.794), and 1.825 (95 % CI 1.351-2.464); negative likelihood ratios were respectively 0.212 (95 % CI 0.109-0.414), 0.246 (95 % CI 0.161-0.377), and 0.556 (95 % CI 0.385-0.804); the SROC curves were 19.205, 10.397, and 3.810.

CONCLUSIONS

The two IGRAs showed better performance than TST for the diagnosis of the tuberculosis. However, neither of them showed stability in the diagnosis of TB.

Pulmonary Tuberculosis in Humanized Mice Infected with HIV-1

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

Utility of QuantiFERON-TB Gold In-Tube Test in the Diagnosis of Latent TB in HIV-Positive Patients in a Medium-TB Burden Country

BACKGROUND

The authors aimed to compare TST with QuantiFERON-TB Gold In-Tube (QFT) for detecting latent tuberculosis infection (LTBI) in HIV-infected patients in Iran as a TB-medium endemic country.

METHODS

In a cross-sectional design,130 HIV-positive patients in HIV clinic of Tehran University were studied. Patients screened for LTBI with QFT and TST simultaneously. Concordance between 2 tests results and variables associated with tests discordance were assessed.

RESULTS

Positive results found in 24.6% for TST and 7.7% for QFT. Overall agreement between them was 73.85% (Kappa = 0.083). History of imprisonment was associated with more positive TST (P = 0.014) and QFT (P = 0.01). Patients with intravenous drug use (IDU) history had significant discordant results (0.018).

CONCLUSION

The authors recommend QFT for all negative cases of TST in HIV-positive patients especially who had history of IDU.

Moxifloxacin Prophylaxis against MDR TB, New York, New York, USA

Contacts of persons infected with multidrug-resistant tuberculosis (MDR TB) have few prophylaxis options. Of 50 contacts of HIV- and MDR TB–positive persons who were treated with moxifloxacin, 30 completed treatment and 3 discontinued treatment because of gastrointestinal symptoms. Moxifloxacin was generally well-tolerated; further research of its efficacy against MDR TB is needed.

Latent tuberculosis infection: myths, models, and molecular mechanisms

The aim of this review is to present the current state of knowledge on human latent tuberculosis infection (LTBI) based on clinical studies and observations, as well as experimental in vitro and animal models. Several key terms are defined, including "latency," "persistence," "dormancy," and "antibiotic tolerance." Dogmas prevalent in the field are critically examined based on available clinical and experimental data, including the long-held beliefs that infection is either latent or active, that LTBI represents a small population of nonreplicating, "dormant" bacilli, and that caseous granulomas are the haven for LTBI. The role of host factors, such as CD4(+) and CD8(+) T cells, T regulatory cells, tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ), in controlling TB infection is discussed. We also highlight microbial regulatory and metabolic pathways implicated in bacillary growth restriction and antibiotic tolerance under various physiologically relevant conditions. Finally, we pose several clinically important questions, which remain unanswered and will serve to stimulate future research on LTBI.

Prevention of HIV-associated opportunistic infections and diseases in the age of highly active antiretroviral therapy

Since the introduction of highly active antiretroviral therapy (HAART), the rates of opportunistic infections have decreased markedly as has overall morbidity and mortality from HIV infection in developed countries. However, opportunistic infections remain the most important cause of death in HIV-infected people due to both late presentation of HIV infections and failure of HAART to adequately restore cell-mediated immunity in all individuals. While prophylaxis may be discontinued in patients who have responded to HAART with sustained increases of their CD4 counts above risk thresholds, for those patients who fail HAART, those who are unable to tolerate it, or whose treatments are interrupted, opportunistic-infection prophylaxis remains essential. Some HIV-associated diseases, such as anogenital human papilloma virus-induced neoplasia and hepatitis C infection, have not decreased in frequency with the advent of HAART. For these conditions, effective screening and treatment programs will be necessary to prevent ongoing morbidity. This review will provide an update on HIV-associated opportunistic infections and their prevention in the age of HAART, as well as discuss novel presentations of opportunistic illnesses, such as immune restoration syndromes.

Multiple oesophago-respiratory fistulae: sequelae of pulmonary tuberculosis in retroviral infection

Pulmonary tuberculosis (PTB) is a common infectious disease worldwide. However, mediastinal tuberculous lymphadenitis complicated by oesophageal involvement and oesophago-respiratory fistula is now uncommon due to improved anti-tuberculous regimes and better general awareness. The overall incidence of acquired oesophago-respiratory fistula due to infection is low, and therefore, the lesion is not often a frontrunner in differential diagnosis. Still, tuberculous oesophago-respiratory fistulae can potentially occur in patients with retroviral disease, as they tend to have atypical and more virulent manifestations. In this study, we report the case of multiple oesophago-respiratory fistulae in a patient with PTB and retroviral disease, and highlight the computed tomography features of these lesions as an atypical presentation of PTB in retroviral disease. Clinicians should suspect oesophago-respiratory fistulae if patients present with Ono’s sign, and remain particularly vigilant for patients with underlying PTB and retroviral disease, as early diagnosis and treatment could help to reduce mortality.

HIV and Tuberculosis co-infection impacts T-cell activation markers but not the numbers subset of regulatory T-cells in HIV-1 infected patients

Background

Tuberculosis (TB) has been shown to accelerate the clinical course of HIV infection, but the mechanisms by which this occurs are not well understood. Regulatory T-cells (Tregs) are known to dampen hyperactivation of the immune cells, but it remains unclear whether hyperactivation of T-cells in HIV infection is associated with a decrease of Tregs and what the effect Mycobacterium tuberculosis (MTB) co-infection has on T-cell activation and Tregs.

Objectives

In this study, we aim to evaluate whether active TB is associated with the increased expression of T-cell activation markers and reduced number of Treg cells in HIV-1-infected patients.

Methods

This study was conducted on 69 subjects consisting of 20 HIV-infected patients, 20 HIV and MTB co-infected patients, 19 MTB-infected patients and 10 uninfected control subjects negative for both MTB and HIV. The frequencies of T-cell activation markers (CD38 and HLA-DR) and Treg cells (CD4⁺CD25⁺CD127-) were measured by flow cytometry.

Results

Significantly higher expression of CD38 and HLA-DR on CD4⁺ and CD8⁺ T-cells was found in MTB and HIV co-infected patients compared with HIV-infected patients. However, no significant difference in the percentage of Treg cells was reported between HIV patients with TB and those without. The study also showed a negative correlation between regulatory T-cells frequency and CD4⁺ T-cell counts.

Conclusion

These results suggest that TB enhances the expression of peripheral T-cell activation markers during HIV infection, whilst having no impact on the percentages of Treg cells.

Risk factors of tuberculosis infection among HIV/AIDS patients in Burkina Faso

Tuberculosis (TB) and HIV coinfection is the leading cause of mortality among TB patients and people living with HIV/AIDS (PLWHAs). There is still a need to look for cognitive and behavioral determinants of TB among PLWHAs. This study aims at identifying risk factors of TB infection among PLWHAs in Burkina Faso. A cross-sectional study design and consecutive recruitment method were employed. Adult patients attending TB hospitals or HIV clinics were recruited in two main regions (Hauts-Bassins and Centre) of Burkina Faso from August to October 2010. Stepwise logistic regression models were used for statistical analysis. In total, 734 PLWHAs, including 181 (24.7%) coinfected with TB, participated in this study. Of the latter, 53.4% were from the Hauts-Bassins region and 46.6% from the Centre region. Adjusted TB risk factors among PLWHAs were urban setting, TB history, higher number of persons living in the household, and poor geographic access to care. Moreover adjusted TB risk factors among PLWHAs consisted of CD4 cell counts below 200/μl, a history of sexually transmissible infections, and a past or present history of pulmonary asthma. In addition, lack of education and arterial hypertension were additional risk factors in the Hauts-Bassins region; for PLWHAs in the Centre region, male gender, jobs not in the private and public sector, and past or present history of cardiovascular disease were additional risk factors for TB. Common and different risk factors for TB were identified for PLWHAs in the Hauts-Bassins and Centre regions. This information will be incorporated into the HIV/TB control programs in the future.

Tuberculosis, injecting drug use and integrated HIV-TB care: a review of the literature

BACKGROUND

People who inject drugs (PWID) are at increased risk of tuberculosis (TB) and reduced retention in treatment. There is a need to document strategies for integrated delivery of HIV, TB and drug dependency care.

METHODS

This article reviews the literature on rates of TB mono- and co-infection, and published and grey literature descriptions of TB and HIV-TB care, among PWID.

RESULTS

Latent TB infection prevalence was high and active disease more common among HIV-positive PWID. Data on multidrug-resistant TB and co-infections among PWID were scarce. Models of TB care fell into six categories: screening and prevention within HIV-risk studies; prevention at TB clinics; screening and prevention within needle-and-syringe-exchange (NSP) and drug treatment programmes; pharmacy-based TB treatment; TB service-led care with harm reduction/drug treatment programmes; and TB treatment within drug treatment programmes. Co-location with NSP and opioid substitution therapy (OST), combined with incentives, consistently improved screening and prevention uptake. Small-scale combined TB treatment and OST achieved good adherence in diverse settings. Successful interventions involved collaboration across services; a client-centred approach; and provision of social care. No peer-reviewed studies described models of integrated HIV-TB care for PWID but grey literature highlighted key components: co-located services, provision of drug treatment, multidisciplinary staff training; and remaining barriers: staffing inefficiencies, inadequate funding, police interference, and limited OST availability.

CONCLUSIONS

Integration with drug treatment improves PWID engagement in TB services but there is a need to document approaches to HIV-TB care, improve surveillance of TB and co-infections among PWID, and advocate for improved OST availability.

Epidemiology of tuberculosis immunology

Immunological impairment plays a major role in the epidemiology of TB. Globally, the most common causes of immunological impairment are malnutrition, diabetes, HIV/AIDS, aging, and smoking. With the notable exception of HIV, each factor leads to relatively mild immunological impairment in individuals. However, as these conditions affect a significant proportion of the population, they contribute substantially to the incidence of TB at a global scale. Understanding immunological impairment is central to understanding the global TB pandemic, and vital to the development of effective disease control strategies.

Contribution of interferon gamma release assays testing to the diagnosis of latent tuberculosis infection in HIV-infected patients: a comparison of QuantiFERON-TB Gold In Tube, T-SPOT.TB and tuberculin skin test

BACKGROUND

Diagnosis and treatment of latent tuberculosis infection (LTBI) is the most effective strategy to control tuberculosis (TB) among patients with HIV infection. The tuberculin skin test (TST) was the only available method to identify LTBI. The aim of the present work was to evaluate the usefulness of the interferon-gamma release assays (IGRAs): QuantiFERON-tuberculosis (TB) Gold-In-Tube test (QFG) and T-SPOT.TB for the diagnosis of LTBI in a diverse cohort of HIV-infected patients.

METHODS

A prospective study was carried out in consecutive patients cared for in a single institution in Spain from January 2009 to October 2010. IGRAs and TST were performed simultaneously. TST induration ≥ 5 mm was considered positive.

RESULTS

QFG, T-SPOT.TB and TST were performed in 373 subjects. Median CD4 cell count was 470/μl with a median nadir of 150/μl. TST, QFG and T-SPOT.TB were positive in 13.3%, 7.5% and 18.5% cases respectively. Among 277 patients with neither past or current TB nor previous treatment for LTBI and who had TST results, a positive TST result was obtained in 20 (7.2%) cases. When adding QFG results to TST, there were a total of 26 (8.6%) diagnoses of LTBI. When the results of both IGRAs were added, the number of diagnoses increased to 54 (17.9%) (incremental difference: 10.7% [95% confidence interval [CI]:5.3-16.2%] [p < 0.001]), and when both IGRAs were added, the number of diagnoses reached 56 (18.5%) (incremental difference: 11.3% [95% CI:5.7%-16.9%] [p < 0.001]). Patients with a CD4 cell count greater than 500 cells/μl and prior stay in prison were more likely to have a diagnosis of LTBI by TST and/or QFG and/or T-SPOT.TB (adjusted odds ratio [aOR]: 3.8; 95% CI, 1.4 - 9.9; and aOR: 3.3; 95% CI, 1.3 - 8.3, respectively).

CONCLUSIONS

IGRAs were more sensitive than TST for diagnosis of M. tuberculosis infection in HIV-infected patients. Dual sequential testing with TST and IGRAs may be the optimal approach for LTBI screening in this population.

Comparison of interferon gamma-inducible protein-10 and interferon gamma-based QuantiFERON TB Gold assays with tuberculin skin test in HIV-infected subjects

We aimed to compare the positivity of the QuantiFERON TB gold in-tube (QFT-IT antigens) specific interferon gamma (IFN-γ/QFT-IT) and IFN-γ-inducible protein-10 (IP-10/QFT-IT) assays with tuberculin skin test (TST) among human immunodeficiency virus (HIV)-infected individuals in a TB endemic setting. A total of 180 HIV-infected subjects, with no evidence of active TB, were recruited. IFN-γ and IP-10 levels specific to QFT-IT antigens were measured in plasma from QFT-IT tubes. The overall positivity of TST at the 5-mm cut-off point (19%) was significantly lower when compared to IFN-γ/QFT-IT (38%) and IP-10/QFT-IT (45%) assays. The positivity of IP-10/QFT-IT was significantly higher than that of IFN-γ/QFT-IT (P = 0.038). Indeterminate results for IFN-γ/QFT-IT and IP-10/QFT-IT were more frequent in subjects with CD4 count <100 cells/μL than in those with >100 cells/μL. IFN-γ/QFT-IT (9%) yielded significantly higher number of indeterminate results than IP-10/QFT-IT (5%). The frequency of these responses is higher than the proportion of individuals with positive TST results. However, 6 IFN-γ/QFT-IT- or IP-10/QFT-IT-negative subjects were positive for TST at the 5-mm cut-off point. Prospective and prognostic studies are required to clarify the significance of these data.

Analysis of microRNA expression profiling identifies miR-155 and miR-155* as potential diagnostic markers for active tuberculosis: a preliminary study

To explore biologic behaviors and disease relevance of microRNAs (miRNAs) in the development of active tuberculosis (ATB), we investigated the expression profile of Mycobacterium tuberculosis (MTB) purified protein derivative (PPD)-induced miRNAs to determine the specific miRNAs involved in the pathogenesis of ATB. The expression profile of miRNA under PPD challenge was first measured using microarray analysis in peripheral blood mononuclear cells isolated from ATB patients and healthy controls (HC). The remarkably reactive miRNAs were then validated in a larger cohort by quantitative real-time polymerase chain reaction (qRT-PCR). The receiver operating characteristic (ROC) curve was plotted to evaluate the diagnostic value of the determined PPD-responsive miRNAs. The potential targets for those miRNAs were also predicted by computational programs. Fourteen of 866 human miRNAs exhibited at least 1.8-fold difference in the ratio of expression level before and after stimulation with PPD between the ATB and HC groups. The qRT-PCR study validated the findings from microarray-based screening, in which miR-155 exhibited a fold change of 1.4 in the HC group and 3.7 in the ATB group upon PPD stimulation (p < 0.0001); miR-155* exhibited a fold change of 1.9 in the HC and 4.6 in the ATB group (p < 0.005). In ROC plots, the area under the curve was 0.8972 for miR-155 and 0.7945 for miR-155*. The background expression of these 2 microRNAs exhibited no differences between the ATB and HC groups. miR-155 and miR-155* exhibited characteristic expression by TB-specific antigen, suggesting that they can be potential diagnostic markers under the challenge of specific MTB antigens.

Lower levels of interleukin-12 precede the development of tuberculosis among HIV-infected women

Tuberculosis (TB) is the worldwide leading cause of death among HIV-infected individuals, accounting for more than half of AIDS-related deaths. A high risk of tuberculosis (TB) has been shown in early stages of the HIV disease, even in the presence of normal CD4(+) cell counts. Moreover, the factors that determine protective immunity vs. susceptibility to Mycobacterium tuberculosis cannot be fully explained by simple changes in IFNγ levels or a shift from Th1 to Th2 cytokines. This work investigated the relationship between cytokine expression profiles in peripheral blood mononuclear cells (PBMC) and susceptibility to M. tuberculosis in 10 HIV+ women who went onto develop TB. RNA transcripts for IL-4, IL-4δ2, IL-10, IL-12(p35), IL-13, IL-17A, IFNγ and TNFα were measured by real-time quantitative PCR in unstimulated or TB peptide antigen-stimulated PBMCs from 10 HIV+ women with positive tuberculin skin tests (TST) and compared with HIV-seropositive and seronegative women without previous TB and negative TST. Stimulated PBMC cultures showed significantly lower expression of IL-12p35 (p=0.004) and IL-10 (p=0.026) in the HIV+TB+ group 6-12months before onset of TB compared to HIV+TB- women. Unstimulated PBMC from HIV+TB+ women also had lower expression of Th2 cytokines [IL-4 (p=0.056) and IL-13 (p=0.050)] compared to HIV+TB- women. These results suggest that lower IL-12 production by PBMC in response to TB antigens and lower levels of both Th1 and Th2 cytokines by PBMC correlate with future development of TB in HIV-infected women and may be responsible for their increased susceptibility.

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.

Interferon-gamma release assays for the diagnosis of latent tuberculosis infection in HIV-infected individuals: a systematic review and meta-analysis

OBJECTIVE

To determine whether interferon-gamma release assays (IGRAs) improve the identification of HIV-infected individuals who could benefit from latent tuberculosis infection therapy.

DESIGN

Systematic review and meta-analysis.

METHODS

We searched multiple databases through May 2010 for studies evaluating the performance of the newest commercial IGRAs (QuantiFERON-TB Gold In-Tube [QFT-GIT] and T-SPOT.TB [TSPOT]) in HIV-infected individuals. We assessed the quality of all studies included in the review, summarized results in prespecified subgroups using forest plots, and where appropriate, calculated pooled estimates using random effects models.

RESULTS

The search identified 37 studies that included 5736 HIV-infected individuals. In three longitudinal studies, the risk of active tuberculosis was higher in HIV-infected individuals with positive versus negative IGRA results. However, the risk difference was not statistically significant in the two studies that reported IGRA results according to manufacturer-recommended criteria. In persons with active tuberculosis (a surrogate reference standard for latent tuberculosis infection), pooled sensitivity estimates were heterogeneous but higher for TSPOT (72%; 95% confidence interval [CI], 62-81%) than for QFT-GIT (61%; 95% CI, 47-75%) in low-/middle-income countries. However, neither IGRA was consistently more sensitive than the tuberculin skin test in head-to-head comparisons. Although TSPOT appeared to be less affected by immunosuppression than QFT-GIT and the tuberculin skin test, overall, differences among the three tests were small or inconclusive.

CONCLUSIONS

Current evidence suggests that IGRAs perform similarly to the tuberculin skin test at identifying HIV-infected individuals with latent tuberculosis infection. Given that both tests have modest predictive value and suboptimal sensitivity, the decision to use either test should be based on country guidelines and resource and logistic considerations.

Complicated skin, skin structure and soft tissue infections - are we threatened by multi-resistant pathogens?

Tissue infections or skin, skin structure, and deep seated soft tissue infections are general terms for infections of the entire skin layer including the subcutaneous and muscle tissue layers and their respective fascia structures. Infections of the different mediastinal fascias (mediastinitis) and retroperitoneal fascia infections also belong to this category. Due to the variability of their clinical presentation, skin and soft tissue infections can be classified according to different features. The following aspects can be used for classification:

- anatomical structures

- pathogens

- necessity for urgent treatment

- extent of infection

The incidence of skin and soft tissue infections in which MRSA (methicillin-resistent Staphylococcus aureus) is involved has been steadily increasing over the past 15 years. These wounds should be treated according to the same open treatment principles as other infected wounds. Since these infections are often superficial contaminations, antibiotic therapy is not indicated. If systemic infection occurs in form of MRSA sepsis, antibiotic therapy is indicated.

Several recent reports identified MRSA as the leading pathogen in SSTIs. It also causes 20% to 50% of diabetes-associated foot infections in several countries and is associated with worse outcomes than other pathogens.

Timing of antiretroviral therapy for HIV in the setting of TB treatment

The convergent human immunodeficiency virus (HIV) and tuberculosis (TB) pandemics continue to collectively exact significant morbidity and mortality worldwide. Highly active antiretroviral therapy (HAART) has been a critical component in combating the scourge of these two conditions as both a preemptive and therapeutic modality. However, concomitant administration of antiretroviral and antituberculous therapies poses significant challenges, including cumulative drug toxicities, drug-drug interactions, high pill burden, and the immune reconstitution inflammatory syndrome (IRIS), thus complicating the management of coinfected individuals. This paper will review data from recent studies regarding the optimal timing of HAART initiation relative to TB treatment, with the ultimate goal of improving coinfection-related morbidity and mortality while mitigating toxicity resulting from concurrent treatment of both infections.

Primate model to study reactivation of TB associated with retroviral infection

Evaluation of: Diedrich CR, Mattila JT, Klein E et al.: Reactivation of latent tuberculosis in cynomolgus macaques infected with SIV is associated with early peripheral T cell depletion and not virus load. PLoS ONE 5(3), e9611 (2010). This work describes the effect of simian immunodeficiency virus (SIV)mac251 infection on clinically inapparent (latent) TB infection in Cynomolgus macaques (Macaca fascicularis). SIV and TB coinfected animals were compared with those with SIV infection alone and with SIV-uninfected animals with latent or active TB. All seven animals with latent TB reactivated within 11 months of SIV infection. Animals were divided into those that reactivated less than 17 weeks post-SIV infection and those that reactivated more than 26 weeks post-SIV infection. Reactivation was independent of viral load but related to depletion of T cells during acute SIV infection. Granulomas from animals with reactivated TB demonstrated a spectrum of distinct pathological features consistent with chronic inflammation. It is of interest to relate these findings to the poorly defined mechanisms by which the risk of human TB increases soon after acquisition of HIV-1 infection. Furthermore, an animal model that faithfully recreates HIV-associated susceptibility to TB would be of great utility when considering novel immune and chemotherapeutic options for HIV and TB coinfected individuals.

Mycobacterium tuberculosis promotes HIV trans-infection and suppresses major histocompatibility complex class II antigen processing by dendritic cells

Mycobacterium tuberculosis is a leading killer of HIV-infected individuals worldwide, particularly in sub-Saharan Africa, where it is responsible for up to 50% of HIV-related deaths. Infection by HIV predisposes individuals to M. tuberculosis infection, and coinfection accelerates the progression of both diseases. In contrast to most other opportunistic infections associated with HIV, an increased risk of M. tuberculosis infection occurs during early-stage HIV disease, long before CD4 T cell counts fall below critical levels. We hypothesized that M. tuberculosis infection contributes to HIV pathogenesis by interfering with dendritic cell (DC)-mediated immune control. DCs carry pathogens like M. tuberculosis and HIV from sites of infection into lymphoid tissues, where they process and present antigenic peptides to CD4 T cells. Paradoxically, DCs can also deliver infectious HIV to T cells without first becoming infected, a process known as trans-infection. Lipopolysaccharide (LPS)-activated DCs sequester HIV in pocketlike membrane invaginations that remain open to the cell surface, and individual virions are delivered from the pocket into T cells at the site of contact during trans-infection. Here we report that M. tuberculosis exposure increases HIV trans-infection and induces viral sequestration within surface-accessible compartments identical to those seen in LPS-stimulated DCs. At the same time, M. tuberculosis dramatically decreases the degradative processing and major histocompatibility complex class II (MHC-II) presentation of HIV antigens to CD4 T cells. Our data suggest that M. tuberculosis infection promotes a shift in the dynamic balance between antigen processing and intact virion presentation, favoring DC-mediated amplification of HIV infections.

Trends in tuberculosis mortality in the United States, 1990-2006: a population-based case-control study

OBJECTIVE

We assessed demographic and temporal trends of tuberculosis (TB)-related deaths in the United States and examined associated comorbidities listed on death certificates.

METHODS

We analyzed TB-related mortality from 1990 through 2006 by examining multiple-cause-of-death data from the National Center for Health Statistics. We assessed age-adjusted mortality rates, secular trends, associations with demographic variables, and comorbid conditions.

RESULTS

From 1990 through 2006, TB was reported as a cause of death among 53,505 people in the U.S. with a combined overall mean age-adjusted mortality rate of 1.16 per 100,000 person-years. The age-adjusted TB mortality rate declined from 2.22 per 100,000 person-years in 1990 to 0.47 per 100,000 person-years in 2006, demonstrating mean annual decline of about 10%. People aged 75 years and older; males; foreign-born people; and those of Hispanic, Asian, black, and Native American race/ethnicity had comparatively elevated TB-related mortality rates. The mortality rate in foreign-born people was more than two times higher than in U.S.-born people. About 89% of deaths among people of Asian race/ethnicity and nearly 50% among black people were foreign-born individuals. Human immunodeficiency virus and selected autoimmune diseases were more common in TB-related deaths.

CONCLUSIONS

TB mortality decreased substantially from 1990 through 2006, but remains an important cause of preventable mortality. The observed decrease was more pronounced among U.S.-born people than among foreign-born people. Disparities in TB-related mortality and the identification of important comorbid conditions can inform strategies targeting subpopulations at increased risk for fatal TB infection.

Role of QuantiFERON-TB gold, interferon gamma inducible protein-10 and tuberculin skin test in active tuberculosis diagnosis

Background

The measurement of Interferon gamma or Interferon gamma inducible protein (IP)-10 in antigen stimulated blood samples is suggested as an alternative method for latent tuberculosis (TB) diagnosis. Nonetheless, their role in active TB diagnosis, particularly in TB endemic settings is yet to be defined. In this study, the sensitivities and specificities of Interferon gamma release assay (IGRA), IP-10 assay and tuberculin skin test (TST) in detecting active TB cases were assessed in human immunodeficiency virus (HIV) sero-negative TB patients and healthy controls respectively.

Methods/Principal Findings

A total of 177 adult TB patients and 100 healthy controls were included for this study. QuantiFERON-TB Gold In-tube (QFT-IT) method was used to analyze the sensitivity and specificity of IGRA. QFT-IT, IP-10 and TST yielded the diagnostic sensitivities of 90.6% (95%CI: 86.3%–94.9%), 92.5% (95%CI: 88.6%–96.4%) and 68.9% (95%CI: 60.6%–77.2%) and specificities of 55% (95% CI: 35.2%–54.8%), 48% (95% CI: 38.2%–57.8%) and 75.5% (95% CI: 66.8%–84.2%), respectively. The extent of pulmonary involvement or presence of diabetes mellitus did not appear to influence the sensitivities of any of these tests. The combination of any of the two tests among QFT-IT, IP-10 and TST showed >98% sensitivity among smear negative cases and particularly the combination of IP-10, TST and smear microscopy showed 100% sensitivity, however, the specificity was decreased to 44.8%.

Conclusions/Significance

QFT-IT and IP-10 were highly sensitive in detecting active TB cases. The combination with TST improved the sensitivity of QFT-IT and IP-10 significantly. Although the higher sensitivity of combination of QFT-IT/IP-10 and TST may be useful in active TB diagnosis, they are limited by their poor specificity due to the high prevalence of latent TB in our settings.

Treatment of latent Mycobacterium tuberculosis infection in intravenous drug users co-infected with HIV

Objective: This clinical trial, carried out among injection drug users and the HIV-infected with tuberculin skin test ≥ 5 mm, aimed to evaluate the compliance and tolerability of two preventive strategies against tuberculosis (TB).

Methods: Study protocol prospectively compares adherence to nine months of daily therapy with isoniazid (9H) versus two months of daily therapy with rifampin plus pyrazinamide (2RZ) administered randomly. All patients were concurrently admitted to a methadone maintenance programme. To assess toxicity, liver function was monitored monthly.

Results: From 305 assessable patients, those in 2RZ arm showed better adherence (84% vs. 59%, p < 0.0001). Results on liver toxicity did not show significant differences between 9H and 2RZ (4.5% vs. 6.9%; odds ratio = 1.58, 95% confidence interval = 0.42—7.24). Conclusion: 2RZ should be considered an option to prevent TB in selected groups of patients infected with HIV, such as injection drug users on methadone treatment.

Modeling the immune rheostat of macrophages in the lung in response to infection

In the lung, alternatively activated macrophages (AAM) form the first line of defense against microbial infection. Due to the highly regulated nature of AAM, the lung can be considered as an immunosuppressive organ for respiratory pathogens. However, as infection progresses in the lung, another population of macrophages, known as classically activated macrophages (CAM) enters; these cells are typically activated by IFN-gamma. CAM are far more effective than AAM in clearing the microbial load, producing proinflammatory cytokines and antimicrobial defense mechanisms necessary to mount an adequate immune response. Here, we are concerned with determining the first time when the population of CAM becomes more dominant than the population of AAM. This proposed "switching time" is explored in the context of Mycobacterium tuberculosis (MTb) infection. We have developed a mathematical model that describes the interactions among cells, bacteria, and cytokines involved in the activation of both AAM and CAM. The model, based on a system of differential equations, represents a useful tool to analyze strategies for reducing the switching time, and to generate hypotheses for experimental testing.

Prevalence and predictors of tuberculosis coinfection among HIV-seropositive patients attending the Aminu Kano Teaching Hospital, northern Nigeria

BACKGROUND

The HIV/AIDS epidemic has been accompanied by a severe epidemic of tuberculosis (TB), although the prevalence of coinfection is largely unknown, especially in developing countries, including Nigeria. The aim of this study was to determine the prevalence and predictors of TB coinfection among HIV-seropositive Nigerians.

METHODS

The case files of HIV/AIDS patients attending Aminu Kano Teaching Hospital, Nigeria from January to December 2006 were reviewed.

RESULTS

A total of 1320 HIV/AIDS patients had complete records and were reviewed, among which 138 (10.5%) were coinfected with TB (95% CI, 8.9% to 12.2%). Pulmonary TB was diagnosed in 103 (74.6%) patients, among whom only 18 (17.5%) were sputum-positive. Fifty (36.2%) coinfected patients had some type of extrapulmonary TB (EPTB); 15 had both pulmonary TB and EPTB. Among the 35 patients with EPTB only, 20 (57.1%) had abdominal TB, 5 (14.3%) had TB adenitis, 5 (14.3%) had spinal TB, 3 (8.6%) were being monitored for tuberculous meningitis, and 1 (2.9%) each had renal TB and tuberculous adrenalitis. The highest prevalence of TB, 13.7% (n = 28), was seen among patients aged 41-50 years. TB coinfection was significantly associated with marital status, WHO clinical stage, and CD4 count. Marital status (OR, 2.1; 95% CI, 1.28-3.59; P = 0.04), WHO clinical stage at presentation (4.81; 1.42-8.34; P = 0.001), and baseline CD4 count (2.71; 1.51-6.21; P = 0.02) remained significant predictors after adjustment for confounding.

CONCLUSIONS

The moderately high prevalence of TB among HIV-seropositive patients underscores the urgent need for strategies that lead to rapid identification and treatment of coinfection with active or latent TB.

Tuberculosis and illicit drug use: review and update

Illicit drug users continue to be a group at high risk for tuberculosis (TB). Here, we present an updated review of the relationship between TB and illicit drug use, and we summarize more than a decade of new research. Drug users, and injection drug users in particular, have driven TB epidemics in a number of countries. The successful identification and treatment of TB among illicit drug users remain important components of a comprehensive TB strategy, but illicit drug users present a unique set of challenges for TB diagnosis and control. New diagnostic modalities, including interferon-gamma-release assays, offer potential for improved diagnosis and surveillance among this group, along with proven treatment strategies that incorporate the use of directly observed therapy with treatment for drug abuse. Special considerations, including coinfection with viral hepatitis and the rifampin-methadone drug interaction, warrant clinical attention and are also updated here.

Communicable Diseases, Globalization of

This article examines the spatial distribution of leading infectious causes of morbidity and mortality worldwide. Beginning with simple models explaining the spatial pattern of infectious diseases, the epidemiologic transition, and disease ecology models, the article focuses on HIV/AIDS, tuberculosis, polio, SARS, and influenza as well as sexually transmitted infections such as gonorrhea. It addresses the problem of disease strain mutation and especially drug resistance, and argues for the application of genotyping in medical geography research. The article emphasizes how migration and increased global interaction are producing a globalization of infectious diseases while at the same time, ethnic residential segregation is producing spatial concentrations of infectious disease or different strains of disease.

Delayed protection by ESAT-6-specific effector CD4+ T cells after airborne M. tuberculosis infection

Mycobacterium tuberculosis infection induces complex CD4 T cell responses that include T helper type 1 (Th1) cells and regulatory T cells. Although Th1 cells control infection, they are unable to fully eliminate M. tuberculosis, suggesting that Th1-mediated immunity is restrained from its full sterilizing potential. Investigation into T cell–mediated defense is hindered by difficulties in expanding M. tuberculosis–specific T cells. To circumvent this problem, we cloned CD4⁺ T cells from M. tuberculosis–infected B6 mice and generated transgenic mice expressing a T cell receptor specific for the immunodominant antigen early secreted antigenic target 6 (ESAT-6). Adoptively transferred naive ESAT-6–specific CD4⁺ T cells are activated in pulmonary lymph nodes between 7 and 10 d after aerosol infection and undergo robust expansion before trafficking to the lung. Adoptive transfer of activated ESAT-6–specific Th1 cells into naive recipients before aerosol M. tuberculosis infection dramatically enhances resistance, resulting in 100-fold fewer bacteria in infected lungs. However, despite large numbers of Th1 cells in the lungs of mice at the time of M. tuberculosis challenge, protection was not manifested until after 7 d following infection. Our results demonstrate that pathogen-specific Th1 cells can provide protection against inhaled M. tuberculosis, but only after the first week of infection.

Incidence of common opportunistic infections in HIV-infected individuals in Pune, India: analysis by stages of immunosuppression represented by CD4 counts

BACKGROUND

Opportunistic infections (OIs) influence the morbidity and mortality due to HIV infections. Data from India on the incidence of OIs among HIV-infected individuals by stages of immunodeficiency are scarce.

METHODS

Between September 2002 and November 2004, HIV-infected individuals were enrolled in a prospective study in Pune. They were clinically and immunologically evaluated quarterly. Incidence rates of specific OIs were calculated.

RESULTS

Median CD4 counts in HIV-infected male and female patients at baseline were 197/mm(3) and 413/mm(3), respectively. Tuberculosis was the most common OI with an incidence of 15.4 (95% CI 12.2-19.2) per 100 person-years, followed by oral candidiasis 11.3 (95% CI 8.6-14.5), herpes zoster 10.1 (95% CI 7.6-13.1), and cryptococcal meningitis 1.7 (95% CI 0.8-3.1) per 100 person-years. Patients with baseline CD4 counts of <200/mm(3) were six times more likely to develop OIs compared to those with CD4 counts of >350/mm(3) (p<0.001).

CONCLUSIONS

The high incidence of commonly reported OIs in Indian HIV-infected individuals highlights the need for early screening and also the need to increase awareness in healthcare providers, in order to improve decisions regarding prophylaxis for prevention and appropriate therapeutic intervention. Emphasis needs to be given to the early diagnosis and management of tuberculosis in HIV-infected individuals.