CD4 cell count recovery in HIV/TB co-infected patients versus TB uninfected HIV patients

Adaptive immunity in different CT patterns of active tuberculosis and possible variability according to patients' geographic provenience

Background

It is still unclear if low lymphocyte levels are directly related to immunological modifications induced by the TB infection or if they depend on the general pre-existing health impairment of affected patients. Our aim was to detect eventual differences in the immunological status of patients with pulmonary TB compared to an age and sex-matched group of hospitalized patients with other bacterial community-acquired pneumonia (CAP). In addition, we tried to assess an association between alterations in the peripheral lymphocyte subsets and the development of different CT patterns of active TB and to discover differences in the immunological status and in the radiological patterns of TB presentation between patients of different geographic proveniences.

Methods

This observational study included 48 patients with TB and 48 sex- and age-matched patients affected by other bacterial CAP. The presence of HIV/AIDS, other immunocompromising conditions, and confounding chronic pulmonary comorbidities was excluded. Flow cytometry was performed on all the enrolled subjects at admission, before starting the appropriate antibiotic therapy. Patients with TB also underwent a computed tomography (CT) scan.

Results

Patients with TB showed a decrease in the absolute count of all the lymphocyte subsets compared to the CAP group. Only the reduction in the percentage of CD4+ T-lymphocytes was significant, while the percentage of CD8+ T-lymphocytes was significantly increased. Patients presenting exudative forms with atypical locations of TB showed a significant reduction in the absolute count and percentage of CD19+ B-lymphocytes compared to those affected by productive TB forms with the typical location. Despite being younger, our black Sub-Saharan Africans showed a significant reduction in the CD4+ T-lymphocytes compartment and a higher prevalence of atypical and exudative forms of TB compared with white Europeans.

Conclusion

Tuberculosis itself may alter peripheral blood lymphocyte subsets compared to other CAP. An impaired CD19+ B-lymphocyte compartment may result in an abnormal exudative response in atypical locations and a suboptimal bacterial control. Other constitutive or environmental causes may influence immunological differences found in patients with TB, particularly in case of different geographic origins. Anyhow, flow cytometry may be of great value in evaluating the immune function of these patients.

Quantification of Mycobacterium tuberculosis and Mycobacterium avium complex in human immunodeficiency virus-infected individuals with and without tuberculosis

Context:

For a dental practitioner, HIV-TB co-infection which is a lethal aliment is an occupational hazard by the virtue of abundant aerosol formation in day to day dental practice.

Aim:

To assess the prevalence of TB co-infection among HIV patients. To assess the infectivity by culturing Mycobacterium Tuberculosis and Mycobacterium avium complex using Lowenstein Jensen medium and Middlebrook medium.

Setting and Design:

One hundred and forty one recently diagnosed HIV seropositive patients were selected. They were divided into two group based on their clinical symptomatology. Sputum samples, CD4 counts and brief case history were collected from these patients.

Subjects and Methods:

Sputum samples were homogenized using modified Petroff 's method. The samples were cultured using Lowenstein Jensen and Middlebrook media. Cultures were interpreted after two weeks of incubation and the cultures were quantified based on their number of colonies produced on them.

Statistical Analysis:

Descriptive statistical analyses followed by Chi square test were performed to assess the prevalence and variation of TB co-infection.

Results:

Prevalence of TB in our sample is 25.53%. Higher CFU of MTB and MAC are obtained in patients symptomatic for TB. MB yields higher CFU than LJ.

Conclusion:

Clinical symptoms alone cannot act as basis for suspecting TB in HIV patients. Mycobacterial cultures should be used as diagnostic aids and preferably both the mediums have to be used.

Outcomes of highly active antiretroviral therapy and its predictors: a cohort study focusing on tuberculosis co-infection in South West Ethiopia

BACKGROUND

In this study, we hypothesized that TB co-infection independently increases the risk of poor treatment outcomes in such patients even if they are on antiretroviral therapy (ART). Therefore, this study was aimed at investigating this hypothesis among cohort of adult PLWHs in South West Ethiopia.

METHODOLOGY

Cohort study comparing the immunologic and clinical outcomes of 130 HIV/TB co-infected and 520 only HIV patients starting ART was enrolled. Chi square and student t test were used to compare outcome variables and logistic regression was used to assess the effect of TB on treatment failure.

RESULTS

In this study, TB co-infection didn't increase immunologic failure even in univariate analysis at both 6 [OR, 1.10 (0.59-1.69), P = 0.85] and 12 months [OR, 1.06 (0.58-1.93), P = 0.89] of ART initiation. However, it increased the risk of clinical failure at both 6 [Adjusted Odd Ratio (AOR), 2.90 (1.41-6.09), P = 0.028] and 12 months [AOR, 2.93 (1.41-6.09), P = 0.004] of ART initiation.

CONCLUSION

This study showed that TB co-infection didn't adversely affect the immunologic outcomes, weight and hemoglobin responses even though it increased the risk of clinical failure nearly three times. Therefore, beside the concern given for TB prevention and treatment, several patient and policy related factors need to be addressed to maximally benefit from highly active antiretroviral therapy rollout in resource limited settings.

Is there a need to increase the dose of efavirenz during concomitant rifampicin-based antituberculosis therapy in sub-Saharan Africa? The HIV-TB pharmagene study

AIMS

The current HIV treatment guidelines are inconsistent about the need for weight-based efavirenz dose adjustment during rifampicin containing antituberculosis (anti-TB) cotreatment. We investigated effect of rifampicin-based anti-TB cotreatment on plasma efavirenz exposure and treatment outcome, considering effect of CYP2B6 genotype and bodyweight.

PATIENTS & METHODS

HIV-only (arm 1, n = 285) or TB-HIV (arm 2, n = 208) coinfected patients were enrolled and received efavirenz-based ART alone or with rifampicin-based anti-TB therapy, respectively. Plasma efavirenz concentrations at 4th and 16th weeks, viral load and CD4 cell count at 24th and 48th weeks were determined.

RESULTS

The mean plasma efavirenz concentration at weeks 4 (p = 0.03) and 16 (p = 0.08) was inconsistently higher in arm 2 than arm 1, mainly in CYP2B6*6 carriers. Effect of bodyweight on efavirenz pharmacokinetics was significant only in arm 1, but not in arm 2. Proportion of patients with nondetectable viral load (≤50 copies/ml) at week 24 was higher in arm 1 than arm 2 patients (91.0 vs 76.3%; p = 0.002), but no significant difference was observed at week 48 (89.5 vs 87.8%; p = 0.22).

CONCLUSION

Rifampicin-based anti-TB cotreatment has no significant influence on long-term efavirenz plasma exposure and efficacy. Hence, there is no need to increase the dose of efavirenz during concomitant rifampicin-based anti-TB cotreatment in the sub-Saharan African population.

The effect of tuberculosis treatment on virologic and CD4+ cell count response to combination antiretroviral therapy: a systematic review

OBJECTIVE

To determine the impact of tuberculosis (TB) treatment at the time of combination antiretroviral therapy (cART) initiation on virologic and CD4 cell count response to cART.

METHODS

Systematic review and meta-analysis of studies reporting HIV RNA and CD4 cell count response, stratified by TB treatment status at cART initiation. Stratified random-effects and meta-regression analyses were used when possible.

RESULTS

Twenty-five eligible cohort studies reported data on 49 578 (range 42-15 646) adults, of whom 8826 (18%) were receiving TB treatment at cART initiation. Seventeen studies reported virologic response; 21 reported CD4 cell count response. The summarized random-effects relative risk (RRRE) of virologic suppression in those receiving vs. not receiving TB treatment at different time points following cART initiation was 1.06 (0.86-1.29) at 1-4 months, 0.91 (0.83-1.00) at 6 months, 0.99 (0.94-1.05) at 11-12 months, and 0.99 (0.77-1.28) at 18-48 months. The overall RRRE at 1-48 months was 0.97 (95% confidence interval 0.92-1.03). Available data regarding the effect of TB treatment on virologic failure were heterogeneous and inconclusive (13 estimates). Differences in median CD4 cell count gain between those receiving vs. not receiving TB treatment ranged from -10 to 60 cells/μl (median 27) by 6 months (seven estimates) and -10 to 29 (median 6) by 11-12 months (five estimates), although the heterogeneity of the response measures did not support meta-analysis.

CONCLUSION

Patients receiving TB treatment at cART initiation experience similar virologic suppression and CD4 cell count reconstitution as those not receiving TB treatment, reinforcing the need to start cART during TB treatment and allowing more confidence in clinical decision-making.

Factors predicting discordant virological and immunological responses to antiretroviral therapy in HIV-1 clade C infected Zulu/Xhosa in South Africa

Factors predicting suboptimal CD4 cell recovery have been studied in HIV clade-B infected US and European populations. It is, however, uncertain to what extent these results are applicable to HIV clade-C infected African populations. Multivariate analysis using logistic regression and longitudinal analyses using mixed models were employed to assess the impact of age, gender, baseline CD4 cell count, hemoglobin, body mass index (BMI), tuberculosis and other opportunistic co-infections, and frequencies of regimen change on CD4 cell recovery at 12 and 30 months and on overtime change in CD4 cells among 442 virologically suppressed South Africans. Despite adequate virological response 37% (95% CI:32%–42%) and 83% (95% CI:79%–86%) of patients on antiretroviral therapy failed to restore CD4 cell counts ≥200 cells/mm³ after 12 and ≥500 cells/mm³ after 30 months, respectively, in this South African cohort. Critical risk factors for inadequate recovery were older age (p = 0.001) and nadir CD4 cell count at ART initiation (p<0.0001), while concurrent TB co-infection, BMI, baseline hemoglobin, gender and antiretroviral regimen were not significant risk factors. These data suggest that greater efforts are needed to identify and treat HAART-eligible patients prior to severe CD4 cell decline or achievement of advanced age.

A review of murine models of latent tuberculosis infection

The mechanisms of latency and the causes of reactivation of Mycobacterium tuberculosis remain poorly understood; an important reason for this gap in knowledge is the absence of a standardized animal model of latent tuberculosis infection (LTBI). A complete LTBI model should incorporate 2 aspects of LTBI: a persistent infection model with a low bacterial load and a latent infection model that is modified from the Cornell model. Many parameters must be carefully considered to establish an LTBI model, including the inoculating dose, the route of infection, the time interval between infection and the initiation of antibiotic therapy, and the genetic background of the host animal. The responsiveness of this mouse model of LTBI can be assessed through the integrated use of indices, including Karnofsky performance status, bacterial load in spleen and lungs, induced levels of interferon-gamma and tumour necrosis factor-alpha, expression of interleukin (IL)-10 and IL-4 in tissues, specific antigen load in organs, time required for hormone-induced TB relapse, expression level of dormancy genes, and CD4 T-cell count.