Subtherapeutic Rifampicin Concentration Is Associated With Unfavorable Tuberculosis Treatment Outcomes.

BACKGROUND: The relationships between first-line drug concentrations and clinically important outcomes among patients with tuberculosis (TB) remain poorly understood. METHODS: We enrolled a prospective cohort of patients with new pulmonary TB receiving thrice-weekly treatment in India. The maximum plasma concentration of each drug was determined at months 1 and 5 using blood samples drawn 2 hours postdose. Subtherapeutic cutoffs were: rifampicin <8 µg/mL, isoniazid <3 µg/mL, and pyrazinamide <20 µg/mL. Factors associated with lower log-transformed drug concentrations, unfavorable outcomes (composite of treatment failure, all-cause mortality, and recurrence), and individual outcomes were examined using Poisson regression models. RESULTS: Among 404 participants, rifampicin, isoniazid, and pyrazinamide concentrations were subtherapeutic in 85%, 29%, and 13%, respectively, at month 1 (with similar results for rifampicin and isoniazid at month 5). Rifampicin concentrations were lower with human immunodeficiency virus coinfection (median, 1.6 vs 4.6 µg/mL; P = .015). Unfavorable outcome was observed in 19%; a 1-µg/mL decrease in rifampicin concentration was independently associated with unfavorable outcome (adjusted incidence rate ratio [aIRR], 1.21 [95% confidence interval {CI}, 1.01-1.47]) and treatment failure (aIRR, 1.16 [95% CI, 1.05-1.28]). A 1-µg/mL decrease in pyrazinamide concentration was associated with recurrence (aIRR, 1.05 [95% CI, 1.01-1.11]). CONCLUSIONS: Rifampicin concentrations were subtherapeutic in most Indian patients taking a thrice-weekly TB regimen, and low rifampicin and pyrazinamide concentrations were associated with poor outcomes. Higher or more frequent dosing is needed to improve TB treatment outcomes in India.

Correction: Smoking, alcohol use disorder and tuberculosis treatment outcomes: A dual co-morbidity burden that cannot be ignored.

[This corrects the article DOI: 10.1371/journal.pone.0220507.].

Smoking, alcohol use disorder and tuberculosis treatment outcomes: A dual co-morbidity burden that cannot be ignored.

BACKGROUND: More than 20% of tuberculosis (TB) disease worldwide may be attributable to smoking and alcohol abuse. India is the second largest consumer of tobacco products, a major consumer of alcohol particularly among males, and has the highest burden of TB globally. The impact of increasing tobacco dose, relevance of alcohol misuse and past versus current or never smoking status on TB treatment outcomes remain inadequately defined. METHODS: We conducted a multi-centric prospective cohort study of newly diagnosed adult pulmonary TB patients initiated on TB treatment and followed for a minimum of 6 months to assess the impact of smoking status with or without alcohol abuse on treatment outcomes. Smokers were defined as never smokers, past smokers or current smokers. Alcohol Use Disorder Identification Test (AUDIT) scores were used to assess alcohol misuse. The association between smoking status and treatment outcomes was assessed in univariate and multivariate random effects poisson regression models. RESULTS: Of 455 enrolled, 129 (28%) had a history of smoking with 94 (20%) current smokers and 35 (8%) past smokers. Unfavourable treatment outcomes were significantly higher among past and current smokers as compared to never smokers. Specifically, the risk of treatment failure was significantly higher among past smokers (aIRR = 2.66, 95% CI: 1.41-4.90, p = 0.002), recurrent TB among current smokers (aIRR = 2.94, 95% CI: 1.30-6.67, p = 0.010) and death among both past (2.63, 95% CI: 1.11-6.24, p = 0.028) and current (aIRR = 2.59, 95% CI: 1.29-5.18, p = 0.007) smokers. Furthermore, the combined effect of alcohol misuse and smoking on unfavorable treatment outcomes was significantly higher among past smokers (aIRR: 4.67, 95% CI: 2.17-10.02, p<0.001) and current smokers (aIRR: 3.58, 95% CI: 1.89-6.76, p<0.001). CONCLUSION: Past and current smoking along with alcohol misuse have combined effects on increasing the risk of unfavourable TB treatment outcomes. Innovative interventions that can readily address both co-morbidities are urgently needed.

Infection free "resisters" among household contacts of adult pulmonary tuberculosis.

Despite substantial exposure to infectious pulmonary tuberculosis (TB) cases, some household contacts (HHC) never acquire latent TB infection (LTBI). Characterizing these "resisters" can inform who to study immunologically for the development of TB vaccines. We enrolled HHCs of culture-confirmed adult pulmonary TB in India who underwent LTBI testing using tuberculin skin test (TST) and QuantiFERON TB Gold Test-in-tube (QFT-GIT) at baseline and, if negative by both (<5mm TST and <0.35IU/mL QFT-GIT), underwent follow-up testing at 4-6 and/or 12 months. We defined persons with persistently negative LTBI tests at both baseline and followup as pLTBI- and resisters as those who had a high exposure to TB using a published score and remained pLTBI-. We calculated the proportion of resisters overall and resisters with complete absence of response to LTBI tests (0mm TST and/or QFT-GIT <0.01 IU/ml). Using random effects Poisson regression, we assessed factors associated with pLTBI-. Of 799 HHCs in 355 households, 67 (8%) were pLTBI- at 12 months; 52 (6.5%) pLTBI- in 39 households were resisters. Complete absence of response to LTBI tests was found in 27 (53%) resisters. No epidemiological characteristics were associated with the pLTBI- phenotype. LTBI free resisters among HHC exist but are uncommon and are without distinguishing epidemiologic characteristics. Assessing the genetic and immunologic features of such resister individuals is likely to elucidate mechanisms of protective immunity to TB.

Tuberculin skin test and QuantiFERON-Gold In Tube assay for diagnosis of latent TB infection among household contacts of pulmonary TB patients in high TB burden setting.

BACKGROUND: World Health Organization (WHO) recommends systematic screening of high-risk populations, including household contacts (HHCs) of adult pulmonary tuberculosis (TB) patients, as a key strategy for elimination of TB. QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and tuberculin skin test (TST) are two commonly used tools for the detection of latent tuberculosis infection (LTBI) but may yield differential results, affecting eligibility for TB preventive therapy. MATERIALS AND METHODS: A prospective cohort study of adult pulmonary TB patients and their HHCs were recruited in 2 cities of India, Pune and Chennai. HHCs underwent QFT-GIT (QIAGEN) and TST (PPD SPAN 2TU/5TU). A positive QFT-GIT was defined as value ≥0.35 IU/ml and a positive TST as an induration of ≥5 mm. A secondary outcome of TST induration ≥10mm was explored. Proportion positive by either or both assays, discordant positives and negatives were calculated; test concordance was assessed using percentage agreement and kappa statistics; and risk factors for concordance and discordance including age categories were assessed using logistic regression. Sensitivity and specificity was estimated by latent class model. RESULTS: Of 1048 HHCs enrolled, 869 [median (IQR) age: 27 years (15-40)] had both TST and QFT-GIT results available and prevalence of LTBI by QFT-GIT was 54% [95% CI (51, 57)], by TST was 55% [95% CI (52, 58)], by either test was 74% [95% CI (71, 77) and by both tests was 35% [95% CI (31, 38)]. Discordance of TST+/QFT-GIT- was 21% while TST-/QFT-GIT+ was 26%. Poor to fair agreement occurred with TST 5mm or 10mm cutoff (60 and 61% agreement with kappa value of 0.20 and 0.25 respectively). Test agreement varied by age, TST strength and induration cut-off. In multivariate analysis, span PPD was a risk factor for QFT-GIT+ and TST- while absence of BCG scar was for TST+ and QFT-GIT-. Being employed and exposure to TB case outside the household case were associated with positivity by both the tests. Sensitivity of TST and QFT-GIT to diagnose LTBI was 77% and 69%. Probability of having LTBI was >90% when both tests were positive irrespective of exposure gradient. CONCLUSION: Prevalence of LTBI among HHCs of adult pulmonary TB patients in India is very high and varies by test type, age, and exposure gradient. In our high TB burden setting, a strategy to treat all HHCs or a targeted strategy whereby an exposure index is used should be assessed in future preventive therapy and vaccine studies as HHCs have several factors that place them at high risk for progression to TB disease.

Daily vs Intermittent Antituberculosis Therapy for Pulmonary Tuberculosis in Patients With HIV: A Randomized Clinical Trial.

Importance: The benefit of daily over thrice-weekly antituberculosis therapy among HIV-positive patients with pulmonary tuberculosis (TB) who are receiving antiretroviral therapy remains unproven. Objective: To compare the efficacy and safety of daily, part-daily, and intermittent antituberculosis therapy regimens in the treatment of HIV-associated pulmonary TB. Design, Setting, and Participants: This open-label, randomized clinical trial was conducted by the National Institute for Research in Tuberculosis, south India. Adults infected with HIV with newly diagnosed, culture-positive, pulmonary TB were enrolled between September 14, 2009, and January 18, 2016. Interventions: Patients were randomized to daily, part-daily, and intermittent antituberculosis therapy regimens, stratified by baseline CD4 lymphocyte count and sputum smear grade. Antiretroviral therapy was initiated as per national guidelines. Clinical and sputum microbiological examinations of patients were performed monthly until 18 months after randomization. Adverse events were recorded using standard criteria. Main Outcomes and Measures: The primary outcome was favorable response, defined as treatment completion with all available sputum cultures negative for Mycobacterium tuberculosis during the last 2 months of treatment. Unfavorable responses included treatment failures, dropouts, deaths, and toxic effects among regimens. Results: Of 331 patients (251 [76%] male; mean [SD] age, 39 [9] years; mean [SD] HIV viral load, 4.9 [1.2] log10 copies/mL; and median [interquartile range] CD4 lymphocyte count, 138 [69-248] cells/µL), favorable responses were experienced by 91% (89 of 98), 80% (77 of 96), and 77% (75 of 98) in the daily, part-daily, and intermittent regimens, respectively. With the difference in outcome between daily and intermittent regimens crossing the O'Brien-Fleming group sequential boundaries and acquired rifampicin resistance emergence (n = 4) confined to the intermittent group, the data safety monitoring committee halted the study. A total of 18 patients died and 18 patients dropped out during the treatment period in the 3 regimens. Six, 4, and 6 patients in the daily, part-daily, and intermittent regimens, respectively, had TB recurrence. Conclusions and Relevance: Among HIV-positive patients with pulmonary TB receiving antiretroviral therapy, a daily anti-TB regimen proved superior to a thrice-weekly regimen in terms of efficacy and emergence of rifampicin resistance. Trial Registration: clinicaltrials.gov Identifier: NCT00933790.