Harriet Mayanja

Duration of efficacy of treatment of latent tuberculosis infection in HIV-infected adults

BackgroundTreatment of latent infection is needed to protect HIV-infected individuals against tuberculosis. A previous report addressed short-term efficacy of three regimens in HIV-infected adults. We now report on long-term efficacy of the study regimens. MethodsThree daily self-administered regimens were compared in a randomized placebo-controlled trial in 2736 purified protein derivative (PPD)-positive and anergic HIV-infected adults. PPD-positive subjects were treated with isoniazid (INH) for 6 months (6H), INH plus rifampicin for 3 months (3HR), INH plus rifampicin and pyrazinamide for 3 months (3HRZ), or placebo for 6 months. Anergic subjects were randomized to 6H or placebo. Results6H initially protected against tuberculosis in PPD-positive individuals; however, benefit was lost within the first year of treatment. Sustained benefit was observed in persons receiving 3HR and 3HRZ. In a Cox regression analysis, the adjusted relative risk for tuberculosis compared with placebo was 0.67 [95% confidence interval (CI), 0.42–1.07] for 6H, 0.49 (95% CI, 0.29–0.82) for 3HR, and 0.41 (95% CI, 0.22-0.76) for 3HRZ. When the rifampicin-containing regimens were combined, the adjusted relative risk for tuberculosis compared with placebo was 0.46 (95% CI, 0.29–0.71). Among anergic subjects, a modest degree of protection with 6H was present (adjusted relative risk, 0.61; 95% CI, 0.32–1.16). Treatment of latent tuberculosis infection had no effect on mortality. ConclusionSix months of INH provided short-term protection against tuberculosis in PPD-positive HIV-infected adults. Three month regimens including INH plus rifampicin or INH, rifampicin and pyrazinamide provided sustained protection for up to 3 years.

Immunogenicity of Novel DosR Regulon-Encoded Candidate Antigens of Mycobacterium tuberculosis in Three High-Burden Populations in Africa

ABSTRACT Increasing knowledge about DosR regulon-encoded proteins has led us to produce novel Mycobacterium tuberculosis antigens for immunogenicity testing in human populations in three countries in Africa to which tuberculosis (TB) is endemic. A total of 131 tuberculin skin test-positive and/or ESAT-6/CFP10-positive, human immunodeficiency virus-negative adult household contacts of active pulmonary TB cases from South Africa (n = 56), The Gambia (n = 26), and Uganda (n = 49) were tested for gamma interferon responses to 7 classical and 51 DosR regulon-encoded M. tuberculosis recombinant protein antigens. ESAT-6/CFP10 fusion protein evoked responses in >75% of study participants in all three countries. Of the DosR regulon-encoded antigens tested, Rv1733c was the most commonly recognized by participants from both South Africa and Uganda and the third most commonly recognized antigen in The Gambia. The four most frequently recognized DosR regulon-encoded antigens in Uganda (Rv1733c, Rv0081, Rv1735c, and Rv1737c) included the three most immunogenic antigens in South Africa. In contrast, Rv3131 induced the highest percentage of responders in Gambian contacts (38%), compared to only 3.4% of Ugandan contacts and no South African contacts. Appreciable percentages of TB contacts with a high likelihood of latent M. tuberculosis infection responded to several novel DosR regulon-encoded M. tuberculosis proteins. In addition to significant similarities in antigen recognition profiles between the three African population groups, there were also disparities, which may stem from genetic differences between both pathogen and host populations. Our findings have implications for the selection of potential TB vaccine candidates and for determining biosignatures of latent M. tuberculosis infection, active TB disease, and protective immunity.

Response to Antiretroviral Therapy in HIV-Infected Patients Attending a Public, Urban Clinic in Kampala, Uganda

BACKGROUND Access to antiretroviral therapy and human immunodeficiency virus (HIV) care is increasing in resource-limited settings. We evaluated clinical, behavioral, and demographic risk factors associated with virologic suppression in a public, urban clinic in Kampala, Uganda. METHODS We conducted a cross-sectional, observational study of 137 HIV-infected patients who were receiving antiretroviral therapy at the infectious diseases clinic at Mulago Hospital (Kampala). We measured the prevalence of viral suppression, evaluated risk factors associated with virologic failure, and documented phenotypic resistance patterns and genotypic mutations. RESULTS A total of 91 (66%) of 137 participants had an undetectable viral load (< 400 copies/mL) after a median duration of 38 weeks (interquartile range, 24-62 weeks) of antiretroviral therapy. Median CD4 cell count was 163 cells/mm3 (interquartile range, 95-260 cells/mm3). The majority of the patients (91%) were treated with nonnucleoside reverse-transcriptase inhibitor-based 3-drug regimens. In multivariate analysis, treatment with the first antiretroviral regimen was associated with viral suppression (odds ratio, 2.6; 95% confidence interval, 1.1-6.1). In contrast, a history of unplanned treatment interruption was associated with virologic treatment failure (odds ratio, 0.2; 95% confidence interval, 0.1-0.6). Of 124 participants treated with nonnucleoside reverse-transcriptase inhibitors, 27 (22%) were documented to have experienced virologic treatment failure. The most common mutation detected was K103N (found in 14 of 27 patients with virologic treatment failure). CONCLUSIONS Although many HIV-infected people treated in Kampala, Uganda, have advanced HIV disease, the majority of patients who received antiretroviral therapy experienced viral suppression and clinical benefit. Because of the frequent use of nonnucleoside reverse-transcriptase inhibitor-based therapy, the majority of resistance was against this drug class. In resource-limited settings, initiation of therapy with a potent, durable regimen, accompanied by stable drug supplies, will optimize the likelihood of viral suppression.

Genomic survey of the non-cultivatable opportunistic human pathogen, enterocytozoon bieneusi

Enterocytozoon bieneusi is the most common microsporidian associated with human disease, particularly in the immunocompromised population. In the setting of HIV infection, it is associated with diarrhea and wasting syndrome. Like all microsporidia, E. bieneusi is an obligate, intracellular parasite, but unlike others, it is in direct contact with the host cell cytoplasm. Studies of E. bieneusi have been greatly limited due to the absence of genomic data and lack of a robust cultivation system. Here, we present the first large-scale genomic dataset for E. bieneusi. Approximately 3.86 Mb of unique sequence was generated by paired end Sanger sequencing, representing about 64% of the estimated 6 Mb genome. A total of 3,804 genes were identified in E. bieneusi, of which 1,702 encode proteins with assigned functions. Of these, 653 are homologs of Encephalitozoon cuniculi proteins. Only one E. bieneusi protein with assigned function had no E. cuniculi homolog. The shared proteins were, in general, evenly distributed among the functional categories, with the exception of a dearth of genes encoding proteins associated with pathways for fatty acid and core carbon metabolism. Short intergenic regions, high gene density, and shortened protein-coding sequences were observed in the E. bieneusi genome, all traits consistent with genomic compaction. Our findings suggest that E. bieneusi is a likely model for extreme genome reduction and host dependence.

Evaluation of a low-cost method, the Guava EasyCD4 assay, to enumerate CD4-positive lymphocyte counts in HIV-infected patients in the United States and Uganda.

Objective: To evaluate the EasyCD4 assay, a less expensive method to enumerate CD4+ lymphocytes, in resource-limited settings. Design: Cross-sectional study conducted in the United States and Uganda. Methods: We compared CD4+ cell counts obtained on replicate samples from HIV-infected patients by the EasyCD4 assay, a microcapillary flow-based system, and by standard flow cytometry or FACSCount with linear regression and the Bland-Altman method. Results: Two hundred eighteen samples were analyzed (77 in the United States and 141 in Uganda). In the United States, mean ± SD CD4 was 697 ± 438 cells/&mgr;L by standard flow cytometry and 688 ± 451 cells/&mgr;L by EasyCD4. In Uganda, the mean ± SD CD4 was 335 ± 331 cells/&mgr;L by FACSCount and 340 ± 327 cells/&mgr;L by EasyCD4. The 2 methods were highly correlated (US cohort, r2 = 0.97, slope = 1.0, intercept = −18; Ugandan cohort, r2 = 0.92; slope = 0.95; intercept = 23). The mean differences in CD4 cell counts were 9.0 and −4.6 cells/&mgr;L for the US and Ugandan cohorts, respectively, and they were not significant in either cohort. In the Ugandan cohort, sensitivity and specificity of the EasyCD4 for CD4 below 200 cells/&mgr;L were 90% and 98%, respectively. Positive predictive value was 96%; negative predictive value was 93%. Conclusions: Our results suggest that EasyCD4 may be used with high positive and negative predictive value in resource-limited settings.

Detection of multiple strains of Mycobacterium tuberculosis using MIRU-VNTR in patients with pulmonary tuberculosis in Kampala, Uganda

BackgroundMany studies using DNA fingerprinting to differentiate Mycobacterium tuberculosis (MTB) strains reveal single strains in cultures, suggesting that most disease is caused by infection with a single strain. However, recent studies using molecular epidemiological tools that amplify multiple targets have demonstrated simultaneous infection with multiple strains of MTB. We aimed to determine the prevalence of MTB multiple strain infections in Kampala, and the impact of these infections on clinical presentation of tuberculosis (TB) and response to treatment.MethodsA total of 113 consecutive smear and culture positive patients who previously enrolled in a house-hold contact study were included in this study. To determine whether infection with multiple MTB strains has a clinical impact on the initial presentation of patients, retrospective patient data (baseline clinical, radiological and drug susceptibility profiles) was obtained. To determine presence of infections with multiple MTB strains, MIRU-VNTR (Mycobacterial Interspersed Repetitive Unit-Variable-Number Tandem Repeats) -PCR was performed on genomic DNA extracted from MTB cultures of smear positive sputum samples at baseline, second and fifth months.ResultsOf 113 patients, eight (7.1%) had infection with multiple MTB strains, coupled with a high rate of HIV infection (37.5% versus 12.6%, p = 0.049). The remaining patients (105) were infected with single MTB strains. The proportions of patients with MTB smear positive cultures after two and five months of treatment were similar. There was no difference between the two groups for other variables.ConclusionInfection with multiple MTB strains occurs among patients with first episode of pulmonary tuberculosis in Kampala, in a setting with high TB incidence. Infection with multiple MTB strains had little impact on the clinical course for individual patients. This is the first MIRU-VNTR-based study from in an East African country.

Innate and Adaptive Immune Responses during Acute M. tuberculosis Infection in Adult Household Contacts in Kampala, Uganda

Contacts of active pulmonary tuberculosis (TB) patients are at risk for Mycobacterium tuberculosis (MTB) infection. Because most infections are controlled, studies during MTB infection provide insight into protective immunity. We compared immune responses of adult household contacts that did and did not convert the tuberculin skin test (TST). Innate and adaptive immune responses were measured by whole blood assay. Responses of TST converters (TSTC) were compared with persistently TST negative contacts (PTST-) and contacts who were TST+ at baseline (TST+). TLR-2, TLR-4, and IFN-γR responses to IFN-γ did not differ between the groups, nor did γδ T cell responses. T cell responses to MTB antigens differed markedly among TSTC, PTST-, and TST+ contacts. Thus, no differences in innate responses were found among the three household contact groups. However, adaptive T cell responses to MTB antigens did differ before and during MTB infection among PTST-, TSTC, and TST+ contacts.

Long-term dominance of Mycobacterium tuberculosis Uganda family in peri-urban Kampala-Uganda is not associated with cavitary disease

BackgroundPrevious studies have shown that Mycobacterium tuberculosis (MTB) Uganda family, a sub-lineage of the MTB Lineage 4, is the main cause of tuberculosis (TB) in Uganda. Using a well characterized patient population, this study sought to determine whether there are clinical and patient characteristics associated with the success of the MTB Uganda family in Kampala.MethodsA total of 1,746 MTB clinical isolates collected from1992-2009 in a household contact study were genotyped. Genotyping was performed using Single Nucleotide Polymorphic (SNP) markers specific for the MTB Uganda family, other Lineage 4 strains, and Lineage 3, respectively. Out of 1,746 isolates, 1,213 were from patients with detailed clinical data. These data were used to seek associations between MTB lineage/sub-lineage and patient phenotypes.ResultsThree MTB lineages were found to dominate the MTB population in Kampala during the last two decades. Overall, MTB Uganda accounted for 63% (1,092/1,746) of all cases, followed by other Lineage 4 strains accounting for 22% (394/1,746), and Lineage 3 for 11% (187/1,746) of cases, respectively. Seventy-three (4 %) strains remained unclassified. Our longitudinal data showed that MTB Uganda family occurred at the highest frequency during the whole study period, followed by other Lineage 4 strains and Lineage 3. To explore whether the long-term success of MTB Uganda family was due to increased virulence, we used cavitary disease as a proxy, as this form of TB is the most transmissible. Multivariate analysis revealed that even though cavitary disease was associated with known risk factors such as smoking (adjusted odds ratio (aOR) 4.8, 95% confidence interval (CI) 3.33-6.84) and low income (aOR 2.1, 95% CI 1.47-3.01), no association was found between MTB lineage and cavitary TB.ConclusionThe MTB Uganda family has been dominating in Kampala for the last 18 years, but this long-term success is not due to increased virulence as defined by cavitary disease.

Comparison of Three Composite Compliance Indices in a Trial of Self-Administered Preventive Therapy for Tuberculosis in HIV-Infected Ugandan Adults

Compliance with tuberculosis preventive therapy in a randomized placebo-controlled trial in 2736 HIV-infected Ugandans was measured using urinary isoniazid metabolite testing, clinic attendance, and self-report. Overall, 77% of urine tests were positive, subjects kept 85% of their scheduled visits while on therapy, and 69% reportedly never forgot to take their medication. Different strategies were used for constructing three composite compliance indices in active arms: (1) an unweighted index of the summed scores on scaled compliance measures; (2) a weighted index using weights obtained from a survey of experts on tuberculosis; and (3) a statistically weighted index using principal components analysis. Composite indices were evaluated for reliability, validity, and practical utility. Understanding of the regimen, study arm, subsequent follow-up, tuberculosis status, and urine spot-check result were associated with composite compliance scores. The unweighted index in this study performed as well as the weighted indices.

Lean Tissue Mass Wasting is Associated With Increased Risk of Mortality Among Women With Pulmonary Tuberculosis in Urban Uganda

OBJECTIVES We assessed the impact of wasting on survival in patients with tuberculosis by using a precise height-normalized lean tissue mass index (LMI) estimated by bioelectrical impedance analysis and body mass index (BMI). METHODS In a retrospective cohort study, 747 adult pulmonary patients with tuberculosis who were screened for HIV and nutritional status were followed for survival. RESULTS Of 747 patients, 310 had baseline wasting by BMI (kg/m(2)) and 103 by LMI (kg/m(2)). Total deaths were 105. Among men with reduced BMI, risk of death was 70% greater (hazard ratio [HR] 1.7, 95% confidence interval [95% CI] 1.03-2.81) than in men with normal BMI. Survival did not differ by LMI among men (HR 1.1; 95% CI 0.5-2.9). In women, both the BMI and LMI were associated with survival. Among women with reduced BMI, risk of death was 80% greater (HR 1.8; 95% CI 0.9-3.5) than in women with normal BMI; risk of death was 5-fold greater (HR 5.0; 95% CI 1.6-15.9) for women with low LMI compared with women with normal LMI. CONCLUSIONS Wasting assessed by reduced BMI is associated with an increased risk for death among both men and women whereas reduced LMI is among women with tuberculosis.