Browsing by Subject "Isoniazid"

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    Antiretroviral therapy for prevention of tuberculosis in adults with HIV: a systematic review and meta-analysis
    (Public Library of Science, 2012) Suthar, Amitabh B; Lawn, Stephen D; Del Amo, Julia; Getahun, Haileyesus; Dye, Christopher; Sculier, Delphine; Sterling, Timothy R; Chaisson, Richard E; Williams, Brian G; Harries, Anthony D
    In a systematic review and meta-analysis, Amitabh Suthar and colleagues investigate the association between antiretroviral therapy and the reduction in the incidence of tuberculosis in adults with HIV infection.
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    Are the effects of isoniaid preventive therapy and highly active antiretroviral therapy additive in preventing HIV-associated tuberculosis
    (2009) Wood, Robin; Lawn, Stephen D; Bekker, Linda-Gail
    Golub et al. [1] recently reported a retrospective analysis of rates of incident tuberculosis (TB) in a large observational cohort of 2778 patients accessing HIV care in rural and urban South Africa. The TB incidence rate was highest [7.1/100 person-years; 95% confidence interval (CI)¼ 6.2–8.2] during the period of care when patients did not receive isoniazid preventive therapy (IPT) or highly active antiretroviral therapy (HAART). The rates were lower during person-time that accrued throughout follow-up after initiation of IPT (5.2/100 person-years; 95% CI¼ 3.4–7.8) and throughout follow-up on HAART alone (4.6/100 person-years, 95% CI¼ 3.4– 6.2). The rate was lower still (1.1/100 person-years 95% CI¼ 0.2–7.6) during person-time accrued during sequential IPT and HAART (IPTþ HAART). The authors concluded that TB risk was significantly reduced by IPT in HAART-treated adults. It was further concluded that 'the dramatic reduction in TB risk' demonstrated in this study together with supportive data from a similarly analysed study from Brazil [2] indicates that widespread use 1444 AIDS 2009, Vol 23 No 11 Fig. 1. T2-weighted flair image demonstrating enhancing lesion in the right precentral gyrus. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. of IPT should be implemented in conjunction with the roll-out of HAART.
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    Are the effects of isoniaid preventive therapy and highly active antiretroviral therapy additive in preventing HIV-associated tuberculosis
    (2009) Wood, Robin; Lawn, Stephen D; Bekker, Linda-Gail
    Golub et al. [1] recently reported a retrospective analysis of rates of incident tuberculosis (TB) in a large observational cohort of 2778 patients accessing HIV care in rural and urban South Africa. The TB incidence rate was highest [7.1/100 person-years; 95% confidence interval (CI)¼ 6.2–8.2] during the period of care when patients did not receive isoniazid preventive therapy (IPT) or highly active antiretroviral therapy (HAART). The rates were lower during person-time that accrued throughout follow-up after initiation of IPT (5.2/100 person-years; 95% CI¼ 3.4–7.8) and throughout follow-up on HAART alone (4.6/100 person-years, 95% CI¼ 3.4– 6.2). The rate was lower still (1.1/100 person-years 95% CI¼ 0.2–7.6) during person-time accrued during sequential IPT and HAART (IPTþ HAART). The authors concluded that TB risk was significantly reduced by IPT in HAART-treated adults. It was further concluded that ‘the dramatic reduction in TB risk’ demonstrated in this study together with supportive data from a similarly analysed study from Brazil [2] indicates that widespread use 1444 AIDS 2009, Vol 23 No 11 Fig. 1. T2-weighted flair image demonstrating enhancing lesion in the right precentral gyrus. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. of IPT should be implemented in conjunction with the roll-out of HAART.
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    Baseline Predictors of Sputum Culture Conversion in Pulmonary Tuberculosis: Importance of Cavities, Smoking, Time to Detection and W-Beijing Genotype
    (Public Library of Science, 2012) Visser, Marianne E; Stead, Michael C; Walzl, Gerhard; Warren, Rob; Schomaker, Michael; Grewal, Harleen M S; Swart, Elizabeth C; Maartens, Gary
    BACKGROUND: Time to detection (TTD) on automated liquid mycobacterial cultures is an emerging biomarker of tuberculosis outcomes. The M. tuberculosis W-Beijing genotype is spreading globally, indicating a selective advantage. There is a paucity of data on the association between baseline TTD and W-Beijing genotype and tuberculosis outcomes. Aim To assess baseline predictors of failure of sputum culture conversion, within the first 2 months of antitubercular therapy, in participants with pulmonary tuberculosis. Design Between May 2005 and August 2008 we conducted a prospective cohort study of time to sputum culture conversion in ambulatory participants with first episodes of smear and culture positive pulmonary tuberculosis attending two primary care clinics in Cape Town, South Africa. Rifampicin resistance (diagnosed on phenotypic susceptibility testing) was an exclusion criterion. Sputum was collected weekly for 8 weeks for mycobacterial culture on liquid media (BACTEC MGIT 960). Due to missing data, multiple imputation was performed. Time to sputum culture conversion was analysed using a Cox-proportional hazards model. Bayesian model averaging determined the posterior effect probability for each variable. RESULTS: 113 participants were enrolled (30.1% female, 10.5% HIV-infected, 44.2% W-Beijing genotype, and 89% cavities). On Kaplan Meier analysis 50.4% of participants underwent sputum culture conversion by 8 weeks. The following baseline factors were associated with slower sputum culture conversion: TTD (adjusted hazard ratio (aHR) = 1.11, 95% CI 1.02; 1.2), lung cavities (aHR = 0.13, 95% CI 0.02; 0.95), ever smoking (aHR = 0.32, 95% CI 0.1; 1.02) and the W-Beijing genotype (aHR = 0.51, 95% CI 0.25; 1.07). On Bayesian model averaging, posterior probability effects were strong for TTD, lung cavitation and smoking and moderate for W-Beijing genotype. CONCLUSION: We found that baseline TTD, smoking, cavities and W-Beijing genotype were associated with delayed 2 month sputum culture. Larger studies are needed to confirm the relationship between the W-Beijing genotype and sputum culture conversion.
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    Epidemic levels of drug resistant tuberculosis (MDR and XDR-TB) in a high HIV prevalence setting in Khayelitsha, South Africa
    (Public Library of Science, 2010) Cox, Helen S; McDermid, Cheryl; Azevedo, Virginia; Muller, Odelia; Coetzee, David; Simpson, John; Barnard, Marinus; Coetzee, Gerrit; van Cutsem, Gilles; Goemaere, Eric
    BACKGROUND: Although multidrug-resistant tuberculosis (MDR-TB) is emerging as a significant threat to tuberculosis control in high HIV prevalence countries such as South Africa, limited data is available on the burden of drug resistant tuberculosis and any association with HIV in such settings. We conducted a community-based representative survey to assess the MDR-TB burden in Khayelitsha, an urban township in South Africa with high HIV and TB prevalence. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey was conducted among adult clinic attendees suspected for pulmonary tuberculosis in two large primary care clinics, together constituting 50% of the tuberculosis burden in Khayelitsha. Drug susceptibility testing (DST) for isoniazid and rifampicin was conducted using a line probe assay on positive sputum cultures, and with culture-based DST for first and second-line drugs. Between May and November 2008, culture positive pulmonary tuberculosis was diagnosed in 271 new and 264 previously treated tuberculosis suspects (sample enriched with previously treated cases). Among those with known HIV status, 55% and 71% were HIV infected respectively. MDR-TB was diagnosed in 3.3% and 7.7% of new and previously treated cases. These figures equate to an estimated case notification rate for MDR-TB of 51/100,000/year, with new cases constituting 55% of the estimated MDR-TB burden. HIV infection was not significantly associated with rifampicin resistance in multivariate analyses. Conclusions/Significance There is an extremely high burden of MDR-TB in this setting, most likely representing ongoing transmission. These data highlight the need to diagnose drug resistance among all TB cases, and for innovative models of case detection and treatment for MDR-TB, in order to interrupt transmission and control this emerging epidemic.
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    Isoniazid preventive therapy for tuberculosis in South Africa: An assessment of the local evidence base
    (2014) Wood, Robin; Bekker, Linda‐Gail
    Worldwide, South Africa (SA) has the worst tuberculosis (TB) epidemic. In SA, there are > 6.1 million people living with HIV (PLWH) and the country now has the largest antiretroviral treatment programme with > 2 million people receiving combination therapy. While there has been a marked recent decline in HIV-associated deaths, > 50% of TB cases still continue to be diagnosed in PWLH. The current TB control strategy based on passive case finding, chemotherapy of childhood TB contacts and directly observed therapy has clearly failed to control endemic TB in SA. Two recent meta-analyses have shown a > 60% reduction in TB in HIV-infected adults after isoniazid preventive therapy (IPT). SA has implemented the World Health Organization policy and IPT is now recommended for HIV-positive people for up to 36 months. Originally, there was only one SA study included in the evidence base supporting this policy, but subsequently four randomised controlled trials have been conducted in SA populations. These studies, together with local observational studies, are the subject of this local, evidence-based review.
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    Pharmacokinetics of Isoniazid, Pyrazinamide, and Ethambutol in newly diagnosed pulmonary TB patients in Tanzania
    (Public Library of Science, 2015) Denti, Paolo; Jeremiah, Kidola; Chigutsa, Emmanuel; Faurholt-Jepsen, Daniel; PrayGod, George; Range, Nyagosya; Castel, Sandra; Wiesner, Lubbe; Hagen, Christian Munch; Christiansen, Michael
    Exposure to lower-than-therapeutic levels of anti-tuberculosis drugs is likely to cause selection of resistant strains of Mycobacterium tuberculosis and treatment failure. The first-line anti-tuberculosis (TB) regimen consists of rifampicin, isoniazid, pyrazinamide, and ethambutol, and correct management reduces risk of TB relapse and development of drug resistance. In this study we aimed to investigate the effect of standard of care plus nutritional supplementation versus standard care on the pharmacokinetics of isoniazid, pyrazinamide and ethambutol among sputum smear positive TB patients with and without HIV. In a clinical trial in 100 Tanzanian TB patients, with or without HIV infection, drug concentrations were determined at 1 week and 2 months post initiation of anti-TB medication. Data was analysed using population pharmacokinetic modelling. The effect of body size was described using allometric scaling, and the effects of nutritional supplementation, HIV, age, sex, CD4+ count, weight-adjusted dose, NAT2 genotype, and time on TB treatment were investigated. The kinetics of all drugs was well characterised using first-order elimination and transit compartment absorption, with isoniazid and ethambutol described by two-compartment disposition models, and pyrazinamide by a one-compartment model. Patients with a slow NAT2 genotype had higher isoniazid exposure and a lower estimate of oral clearance (15.5 L/h) than rapid/intermediate NAT2 genotype (26.1 L/h). Pyrazinamide clearance had an estimated typical value of 3.32 L/h, and it was found to increase with time on treatment, with a 16.3% increase after the first 2 months of anti-TB treatment. The typical clearance of ethambutol was estimated to be 40.7 L/h, and was found to decrease with age, at a rate of 1.41% per year. Neither HIV status nor nutritional supplementations were found to affect the pharmacokinetics of these drugs in our cohort of patients.
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    Rapid urine-based screening for tuberculosis to reduce AIDS-related mortality in hospitalized patients in Africa (the STAMP trial): study protocol for a randomised controlled trial
    (2016) Gupta-Wright, Ankur; Fielding, Katherine L; van Oosterhout, Joep J; Wilson, Douglas K; Corbett, Elizabeth L; Flach, Clare; Reddy, Krishna P; Walensky, Rochelle P; Peters, Jurgens A; Alufandika-Moyo, Melanie; Lawn, Stephen D
    Abstract Background HIV-associated tuberculosis (TB) co-infection remains an enormous burden to international public health. Post-mortem studies have highlighted the high proportion of HIV-positive adults admitted to hospital with TB. Determine TB-LAM and Xpert MTB/RIF assays can substantially increase diagnostic yield of TB within one day of hospital admission. However, it remains unclear if this approach can impact clinical outcomes. The STAMP trial aims to test the hypothesis that the implementation a urine-based screening strategy for TB can reduce all cause-mortality among HIV-positive patients admitted to hospital when compared to current, sputum-based screening. Methods The trial is a pragmatic, individually randomised, multi-country (Malawi and South Africa) clinical trial with two study arms (1:1 recruitment). Unselected HIV-positive patients admitted to medical wards, irrespective of presentation, meeting the inclusion criteria and giving consent will be randomized to screening for TB using either: (i) ‘standard of care’- testing of sputum using the Xpert MTB/RIF assay (Xpert) or (ii) ‘intervention’- testing of sputum using Xpert and testing of urine using (a) Determine TB-LAM lateral-flow assay and (b) Xpert following concentration of urine by centrifugation. Patients will be excluded if they have received TB treatment in the previous 12 months, if they have received isoniazid preventive therapy in the last 6 months, if they are aged <18 years or they live outside the pre-specified geographical area. Results will be provided to the responsible medical team as soon as available to inform decisions regarding TB treatment. Both the study and routine medical team will be masked to study arm allocation. 1300 patients will be enrolled per arm (equal numbers at the two trial sites). The primary endpoint is all-cause mortality at 56 days. An economic analysis will be conducted to project long-term outcomes for shorter-term trial data, including cost-effectiveness. Discussion This pragmatic trial assesses an intervention to reduce the high mortality caused by HIV-associated TB, which could feasibly be scaled up in high-burden settings if shown to be efficacious and cost-effective. We discuss the challenges of designing a trial to assess the impact on mortality of laboratory-based TB screening interventions given frequent initiation of empirical treatment and a failure of several previous clinical trials to demonstrate an impact on clinical outcomes. We also elaborate on the practical and ethical issues of ‘testing a test’ in general. Trial registration ISRCTN Registry (ISRCTN71603869) prospectively registered 08 May 2015; the South African National Controlled Trials Registry (DOH-27-1015-5185) prospectively registered October 2015.
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    A Recent HIV Diagnosis Is Associated with Non-Completion of Isoniazid Preventive Therapy in an HIV-Infected Cohort in Cape Town
    (Public Library of Science, 2012) Oni, Tolu; Tsekela, Relebohile; Kwaza, Bekekile; Manjezi, Lulama; Bangani, Nonzwakazi; Wilkinson, Katalin A; Coetzee, David; Wilkinson, Robert J
    Introduction: Despite high rates of successful treatment TB incidence in South Africa remains high, suggesting ongoing transmission and a large reservoir of latently infected persons. Isoniazid preventive therapy (IPT) is recommended as preventive therapy in HIV-infected persons. However, implementation has been slow, impeded by barriers and challenges including the fear of non-adherence. Objective and Methods: The aim was to evaluate predictors of IPT non-completion. One hundred and sixty four antiretroviral therapy (ART)-naïve HIV-infected patients with tuberculin skin test ≥5 mm were recruited from Khayelitsha day hospital and followed up monthly. A questionnaire was used to collect demographic information. Results: The overall completion rate was 69%. In multivariable analysis, there was a 29% decrease in risk of non-completion for every year after HIV diagnosis (OR 0.81; 95% C.I. 0.68–0.98). Self-reported alcohol drinkers (OR 4.05; 95% C.I. 1.89–9.06) also had a four-fold higher risk of non-completion, with a strong association between alcohol drinkers and smoking (χ2 27.08; p<0.001). Conclusion: We identify patients with a recent HIV diagnosis, in addition to self-reported drinkers and smokers as being at higher risk of non-completion of IPT. The period of time since HIV diagnosis should therefore be taken into account when initiating IPT. Our results also suggest that smokers and alcohol drinkers should be identified and targeted for adherence interventions when implementing IPT on a wider scale.
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    Risk Factors for Acquired Rifamycin and Isoniazid resistance: A systematic review and meta-analysis
    (Public Library of Science, 2015) Rockwood, Neesha; Abdullahi, Leila H; Wilkinson, Robert J; Meintjes, Graeme
    BACKGROUND: Studies looking at acquired drug resistance (ADR) are diverse with respect to geographical distribution, HIV co-infection rates, retreatment status and programmatic factors such as regimens administered and directly observed therapy. Our objective was to examine and consolidate evidence from clinical studies of the multifactorial aetiology of acquired rifamycin and/or isoniazid resistance within the scope of a single systematic review. This is important to inform policy and identify key areas for further studies. METHODS: Case-control and cohort studies and randomised controlled trials that reported ADR as an outcome during antitubercular treatment regimens including a rifamycin and examined the association of at least 1 risk factor were included. Post hoc, we carried out random effects Mantel-Haenszel weighted meta-analyses of the impact of 2 key risk factors 1) HIV and 2) baseline drug resistance on the binary outcome of ADR. Heterogeneity was assessed used I 2 statistic. As a secondary outcome, we calculated median cumulative incidence of ADR, weighted by the sample size of the studies. RESULTS: Meta-analysis of 15 studies showed increased risk of ADR with baseline mono- or polyresistance (RR 4.85 95% CI 3.26 to 7.23, heterogeneity I 2 58%, 95% CI 26 to 76%). Meta-analysis of 8 studies showed that HIV co-infection was associated with increased risk of ADR (RR 3.02, 95% CI 1.28 to 7.11); there was considerable heterogeneity amongst these studies (I 2 81%, 95% CI 64 to 90%). Non-adherence, extrapulmonary/disseminated disease and advanced immunosuppression in HIV co-infection were other risk factors noted. The weighted median cumulative incidence of acquired multi drug resistance calculated in 24 studies (assuming whole cohort as denominator, regardless of follow up DST) was 0.1% (5 th to 95 th percentile 0.07 to 3.2%). CONCLUSION: Baseline drug resistance and HIV co-infection were significant risk factors for ADR. There was a trend of positive association with non-adherence which is likely to contribute to the outcome of ADR. The multifactorial aetiology of ADR in a programmatic setting should be further evaluated via appropriately designed studies.
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    Systematic review of TST responses in people living with HIV in under-resourced settings: implications for isoniazid preventive therapy
    (Public Library of Science, 2012) Kerkhoff, Andrew D; Kranzer, Katharina; Samandari, Taraz; Nakiyingi-Miiro, Jessica; Whalen, Christopher C; Harries, Anthony D; Lawn, Stephen D
    BACKGROUND: People living with HIV (PLWH) who have positive tuberculin skin tests (TST) benefit from isoniazid preventive therapy (IPT) whereas those testing TST-negative do not. Revised World Health Organization guidelines explicitly state that assessment of TST is not a requirement for initiation of IPT. However, it is not known what proportions of patients will benefit from IPT if implemented without targeting according to TST status. We therefore determined the proportions of PLWH who test TST-positive. METHODOLOGY/PRINCIPAL FINDINGS: We systematically reviewed the literature published between January 1990 and February 2012 to determine the proportions of patients without active tuberculosis attending HIV care services in low and middle-income countries who tested TST-positive (≥5 mm induration). Proportions were also determined for different CD4 count strata. Data from 19 studies with 9,478 PLWH from sub-Saharan Africa, Asia and Central and South America were summarized. The vast majority were not receiving antiretroviral therapy (ART). A sub-analysis was conducted of 5 studies (5,567 subjects) from high TB prevalence countries of PLWH with negative TB screens attending HIV care and treatment settings for whom CD4 stratified data were available. The median proportion of PLWH testing TST-positive overall was 22.8% (range, 19.5-32.6%). The median (range) proportions with CD4 cell counts of <200, 200-499 or ≥500 cells/µL who tested positive were 12.4% (8.2-15.3%), 28.4% (20.1-36.9%) and 37.4% (31.3-56.3%), respectively. Heterogeneity in the data precluded calculation of pooled summary estimates. Conclusions/Significance In most settings, if IPT is administered to PLWH pre-ART without assessment of TST status, only a minority of those treated are likely to benefit, especially among those with the lowest CD4 cell counts. This may be inefficient use of resources and cost-effectiveness analyses should take this into account. Local knowledge of TST response rates may help inform policies. New simple means of identifying those who will benefit from IPT are needed to permit appropriate targeting of this intervention.
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    The timing of tuberculosis after isoniazid preventive therapy among gold miners in South Africa: a prospective cohort study
    (2016) Hermans, Sabine M; Grant, Alison D; Chihota, Violet; Lewis, James J; Vynnycky, Emilia; Churchyard, Gavin J; Fielding, Katherine L
    BackgroundThe durability of isoniazid preventive therapy (IPT) in preventing tuberculosis (TB) is limited in high-prevalence settings. The underlying mechanism (reactivation of persistent latent TB or reinfection) is not known. We aimed to investigate the timing of TB incidence during and after IPT and associated risk factors in a very high TB and HIV-prevalence setting, and to compare the observed rate with a modelled estimate of TB incidence rate after IPT due to reinfection.MethodsIn a post-hoc analysis of a cluster-randomized trial of community-wide IPT among South African gold miners, all intervention arm participants that were dispensed IPT for at least one of the intended 9months were included. An incident TB case was defined as any participant with a positive sputum smear or culture, or with a clinical TB diagnosis assigned by a senior study clinician. Crude TB incidence rates were calculated during and after IPT, overall and by follow-up time. HIV status was not available. Multivariable Cox regression was used to analyse risk factors by follow-up time after IPT. Estimates from a published mathematical model of trial data were used to calculate the average reinfection TB incidence in the first year after IPT.ResultsAmong 18,520 participants (96% male, mean age 41years, median follow-up 2.1years), 708 developed TB. The TB incidence rate during the intended IPT period was 1.3/100 person-years (pyrs; 95% confidence interval (CI), 1.0–1.6) and afterwards 2.3/100 pyrs (95% CI, 1.9–2.7). TB incidence increased within 6months followed by a stable rate over time. There was no evidence for changing risk factors for TB disease over time after miners stopped IPT. The average TB incidence rate attributable to reinfection in the first year was estimated at 1.3/100 pyrs, compared to an observed rate of 2.2/100 pyrs (95% CI, 1.8–2.7).ConclusionsThe durability of protection by IPT was lost within 6–12 months in this setting with a high HIV prevalence and a high annual risk of M. tuberculosis infection. The observed rate was higher than the modelled rate, suggesting that reactivation of persistent latent infection played a role in the rapid return to baseline TB incidence.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-016-0589-3) contains supplementary material, which is available to authorized users.
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    Tuberculosis preventive therapy: An underutilised strategy to reduce individual risk of TB and contribute to TB control
    (2014) Churchyard, Gavin J; Chaisson, Richard E; Maartens, Gary; Getahun, Haileyesus
    Tuberculosis (TB) remains a global health problem, and South Africa (SA) has one of the world's worst TB epidemics. The World Health Organization (WHO) estimated in 1999 that one-third of the world's population was latently infected with TB. In SA up to 88% of HIV-uninfected young adults (31 - 35 years) are latently infected with TB. In the most recent meta-analysis, 6 - 12 months of isoniazid preventive therapy (IPT) was associated with a lower incidence of active TB than placebo (relative risk (RR) 0.68; 95% confidence interval (CI) 0.54 - 0.85), with the greatest benefit among individuals with a positive tuberculin skin test (TST) (RR 0.38; 95% CI 0.25 - 0.57). A clinical trial of IPT given with antiretroviral therapy (ART) for 12 months reduced TB incidence by 37% compared with ART alone (hazard ratio (HR) 0.63; 95% CI 0.41 - 0.94). The effect of IPT is limited in high-burden countries. IPT for 36 months v. 6 months reduced TB incidence among HIV-positive, TST-positive participants by 74% (HR 0.26; 95% CI 0.09 - 0.80). A study of more than 24 000 goldminers confirmed that IPT is safe, with only 0.5% experiencing adverse events. A meta-analysis of studies of IPT since 1951 did not show an increased risk of developing resistance. Alternative TB preventive therapy regimens, including high-dose isoniazid and rifapentine given weekly for 3 months, have been shown to have similar efficacy to IPT. Mathematical modelling suggests that scaling up continuous IPT targeted to HIV-positive persons, when used in combination with other treatment and prevention strategies, may substantially improve TB control.