Biomarkers for tuberculosis disease activity, cure, and relapse

B cells in perivascular and peribronchiolar granuloma-associated lymphoid tissue and B-cell signatures identify asymptomatic Mycobacterium tuberculosis lung infection in Diversity Outbred mice

Because most humans resist Mycobacterium tuberculosis infection, there is a paucity of lung samples to study. To address this gap, we infected Diversity Outbred mice with M. tuberculosis and studied the lungs of mice in different disease states. After a low-dose aerosol infection, progressors succumbed to acute, inflammatory lung disease within 60 days, while controllers maintained asymptomatic infection for at least 60 days, and then developed chronic pulmonary tuberculosis (TB) lasting months to more than 1 year. Here, we identified features of asymptomatic M. tuberculosis infection by applying computational and statistical approaches to multimodal data sets. Cytokines and anti-M. tuberculosis cell wall antibodies discriminated progressors vs controllers with chronic pulmonary TB but could not classify mice with asymptomatic infection. However, a novel deep-learning neural network trained on lung granuloma images was able to accurately classify asymptomatically infected lungs vs acute pulmonary TB in progressors vs chronic pulmonary TB in controllers, and discrimination was based on perivascular and peribronchiolar lymphocytes. Because the discriminatory lesion was rich in lymphocytes and CD4 T cell-mediated immunity is required for resistance, we expected CD4 T-cell genes would be elevated in asymptomatic infection. However, the significantly different, highly expressed genes were from B-cell pathways (e.g., Bank1, Cd19, Cd79, Fcmr, Ms4a1, Pax5, and H2-Ob), and CD20+ B cells were enriched in the perivascular and peribronchiolar regions of mice with asymptomatic M. tuberculosis infection. Together, these results indicate that genetically controlled B-cell responses are important for establishing asymptomatic M. tuberculosis lung infection.

Microbiological Cure at Treatment Completion Is Associated With Longer Survival in Patients With Mycobacterium avium Complex Pulmonary Disease

BACKGROUND

Morbidity and mortality from nontuberculous mycobacterial pulmonary disease (NTM-PD) are increasing. Mycobacterium avium complex (MAC) is the most common cause of NTM-PD. Microbiological outcomes are widely used as the primary end point of antimicrobial treatment, but their long-term impact on prognosis is uncertain.

RESEARCH QUESTION

Do patients who achieve microbiological cure at the end of treatment have longer survival than those who do not?

STUDY DESIGN AND METHODS

We retrospectively analyzed adult patients who met the diagnostic criteria for NTM-PD, were infected with MAC species, and were treated with a macrolide-based regimen for ≥ 12 months per guidelines between January 2008 and May 2021 at a tertiary referral center. Mycobacterial culture was performed during antimicrobial treatment to assess the microbiological outcome. Patients with three or more consecutive negative cultures collected ≥ 4 weeks apart and no positive cultures until treatment completion were considered to have achieved microbiological cure. To assess the impact of microbiological cure on all-cause mortality, we performed multivariable Cox proportional hazards regression analysis adjusted for age, sex, BMI, presence of cavitary lesions, erythrocyte sedimentation rate, and underlying comorbid conditions.

RESULTS

Among 382 patients enrolled, 236 (61.8%) achieved microbiological cure at completion of treatment. These patients were younger, had lower erythrocyte sedimentation rates, were less likely to use four or more drugs, and had shorter treatment duration than those who failed to achieve microbiological cure. During a median follow-up of 3.2 (first quartile to third quartile, 1.4-5.4) years after treatment completion, 53 patients died. Microbiological cure was significantly associated with reduced mortality after adjustment for major clinical factors (adjusted hazard ratio, 0.52; 95% CI, 0.28-0.94). The association between microbiological cure and mortality was maintained in a sensitivity analysis that included all patients treated < 12 months.

INTERPRETATION

Microbiological cure at completion of treatment is associated with longer survival in patients with MAC-PD.

Biomarkers Correlated with Tuberculosis Preventive Treatment Response: A Systematic Review and Meta-Analysis

Background: There is a need to identify alternative biomarkers to predict tuberculosis (TB) preventive treatment response because observing the incidence decline renders a long follow-up period. Methods: We searched PubMed, Embase and Web of Science up to 9 February 2023. The biomarker levels during preventive treatment were quantitatively summarized by means of meta-analysis using the random-effect model. Results: Eleven eligible studies, published during 2006–2022, were included in the meta-analysis, with frequently heterogeneous results. Twenty-six biomarkers or testing methods were identified regarding TB preventive treatment monitoring. The summarized standard mean differences of interferon-γ (INF-γ) were −1.44 (95% CI: −1.85, −1.03) among those who completed preventive treatment (τ2 = 0.21; I2 = 95.2%, p < 0.001) and −0.49 (95% CI: −1.05, 0.06) for those without preventive treatment (τ2 = 0.13; I2 = 82.0%, p < 0.001), respectively. Subgroup analysis showed that the INF-γ level after treatment decreased significantly from baseline among studies with high TB burden (−0.98, 95% CI: −1.21, −0.75) and among those with a history of Bacillus Calmette–Guérin vaccination (−0.87, 95% CI: −1.10, −0.63). Conclusions: Our results suggested that decreased INF-γ was observed among those who completed preventive treatment but not in those without preventive treatment. Further studies are warranted to explore its value in preventive treatment monitoring due to limited available data and extensive between-study heterogeneity.

Identification of host biomarkers from dried blood spots for monitoring treatment response in extrapulmonary tuberculosis

There is a lack of objective tools for monitoring treatment response in extrapulmonary tuberculosis (EPTB). This study aimed to explore the utility of inflammatory biomarkers from the dry blood spots (DBS) as a tool for monitoring treatment response in EPTB. In a prospective cohort study, 40 inflammatory biomarkers were investigated in DBS samples from 105 EPTB cases using a Luminex platform. The samples were taken before, and, at the end of the 2nd and 6th months of treatment. A total of 11 inflammatory host biomarkers changed significantly with treatment in all EPTB patients. CXCL9/MIG, CCL20, CCL23, CXCL10/IP-10, CXCL1, CXCL2, and CXCL8 significantly declined in our cohort of EPTB (48 TB pleuritis and 57 TB lymphadenitis) patients at both time points. A biosignature consisting of MIG, CCL23, and CXCL2, corresponded with the treatment response in 81% of patients in the 2nd month and 79% of patients at the end of treatment. MIG, CCL23, IP-10, and CXCL2 changed significantly with treatment in all patients including those showing partial clinical response at the 2nd month of treatment. The changes in the levels of inflammatory biomarkers in the DBS correspond with the treatment success and can be developed as a routine test in low-resource settings.

Methods for handling missing data in serially sampled sputum specimens for mycobacterial culture conversion calculation

BACKGROUND

The occurrence and timing of mycobacterial culture conversion is used as a proxy for tuberculosis treatment response. When researchers serially sample sputum during tuberculosis studies, contamination or missed visits leads to missing data points. Traditionally, this is managed by ignoring missing data or simple carry-forward techniques. Statistically advanced multiple imputation methods potentially decrease bias and retain sample size and statistical power.

METHODS

We analyzed data from 261 participants who provided weekly sputa for the first 12 weeks of tuberculosis treatment. We compared methods for handling missing data points in a longitudinal study with a time-to-event outcome. Our primary outcome was time to culture conversion, defined as two consecutive weeks with no Mycobacterium tuberculosis growth. Methods used to address missing data included: 1) available case analysis, 2) last observation carried forward, and 3) multiple imputation by fully conditional specification. For each method, we calculated the proportion culture converted and used survival analysis to estimate Kaplan-Meier curves, hazard ratios, and restricted mean survival times. We compared methods based on point estimates, confidence intervals, and conclusions to specific research questions.

RESULTS

The three missing data methods lead to differences in the number of participants achieving conversion; 78 (32.8%) participants converted with available case analysis, 154 (64.7%) converted with last observation carried forward, and 184 (77.1%) converted with multiple imputation. Multiple imputation resulted in smaller point estimates than simple approaches with narrower confidence intervals. The adjusted hazard ratio for smear negative participants was 3.4 (95% CI 2.3, 5.1) using multiple imputation compared to 5.2 (95% CI 3.1, 8.7) using last observation carried forward and 5.0 (95% CI 2.4, 10.6) using available case analysis.

CONCLUSION

We showed that accounting for missing sputum data through multiple imputation, a statistically valid approach under certain conditions, can lead to different conclusions than naïve methods. Careful consideration for how to handle missing data must be taken and be pre-specified prior to analysis. We used data from a TB study to demonstrate these concepts, however, the methods we described are broadly applicable to longitudinal missing data. We provide valuable statistical guidance and code for researchers to appropriately handle missing data in longitudinal studies.

Predictors of sputum culture conversion time among MDR/RR TB patients on treatment in a low-income setting

OBJECTIVE

This study aimed to assess the time to first culture conversion and its predictors among MDR/RR-TB cases enrolled in Dilchora Hospital.

METHOD

A retrospective cohort study was conducted among MDR/RR TB cases enrolled between January 2014 and December 2018. SPSS version 26 was used for analysis. Reports are presented using percentages and frequency. Independent predictors of time-to-culture conversion were identified using multivariate Cox proportional hazard regression. Adjusted and crude hazard ratio with 95% CI was used. P-value< 0.05 declared statistical significance.

RESULT

A total of 145 MDR/RR TB cases were included. The median time to culture conversion was at 2 months. Higher baseline hemoglobin [AHR:1.101(1.02-1.19)] and having a non-cavitary lesion on chest x-ray[AHR:1.803(1.15-2.83)] predicted a higher likelihood of early culture conversion. Resistance to at least one first-line anti-TB drug in addition to rifampicin was associated with a lower hazard of early culture conversion as compared to only rifampicin resistance[AHR: 0.577(0.37-0.91)].

CONCLUSION & RECOMMENDATION

A baseline hemoglobin level, chest x-ray finding of cavitation and resistance to rifampicin, and at least one additional drug predicted the time to culture conversion. A closer treatment monitoring and follow-up should be emphasized for those presenting with lower baseline hemoglobin, more drug resistance, and cavitation on chest x-ray.

Clinically encountered growth phenotypes of tuberculosis-causing bacilli and their in vitro study: A review

The clinical manifestations of tuberculosis (TB) vary widely in severity, site of infection, and outcomes of treatment—leading to simultaneous efforts to individualize therapy safely and to search for shorter regimens that can be successfully used across the clinical spectrum. In these endeavors, clinicians and researchers alike employ mycobacterial culture in rich media. However, even within the same patient, individual bacilli among the population can exhibit substantial variability in their culturability. Bacilli in vitro also demonstrate substantial heterogeneity in replication rate and cultivation requirements, as well as susceptibility to killing by antimicrobials. Understanding parallels in clinical, ex vivo and in vitro growth phenotype diversity may be key to identifying those phenotypes responsible for treatment failure, relapse, and the reactivation of bacilli that progresses TB infection to disease. This review briefly summarizes the current role of mycobacterial culture in the care of patients with TB and the ex vivo evidence of variability in TB culturability. We then discuss current advances in in vitro models that study heterogenous subpopulations within a genetically identical bulk culture, with an emphasis on the effect of oxidative stress on bacillary cultivation requirements. The review highlights the complexity that heterogeneity in mycobacterial growth brings to the interpretation of culture in clinical settings and research. It also underscores the intricacies present in the interplay between growth phenotypes and antimicrobial susceptibility. Better understanding of population dynamics and growth requirements over time and space promises to aid both the attempts to individualize TB treatment and to find uniformly effective therapies.

Predictors of slow clinical response and extended treatment in patients with extra-pulmonary tuberculosis in Pakistan, A hospital-based prospective study

The optimal duration of treatment in different forms of extrapulmonary tuberculosis (EPTB) is not clearly defined. This study aimed to identify predictors of slow clinical response and extended anti-TB treatment in EPTB patients. Socio-demographic, clinical, and microbiological characteristics of EPTB patients registered for anti-TB treatment at a tertiary care hospital, were analysed for identification of predictors of extended treatment. A total of 251 patients (137 lymphadenitis, and 114 pleuritis) were included in the analysis. Treatment was extended to more than 6 months in 58/251 (23%) patients. In the multivariate regression analysis, culture-positive EPTB (p = 0.007) [OR (95% CI) = 3.81 (1.43, 10.11)], history of diabetes (p = 0.014) [OR (95% CI) = 25.18 (1.94, 325.83)], smokeless tobacco use (p = 0.002) [OR (95% CI) = 17.69 (2.80, 111.72)], and slow regression of local signs and symptoms after 2 months of treatment (p < 0.001) [OR (95% CI) = 17.09 [(5.79, 50.39)] were seen to be significantly associated with treatment extension. Identification of predictors of extended treatment can help clinical decisions regarding optimal duration of treatment. Further studies are needed to identify subgroups of EPTB patients who can benefit from a shorter or longer treatment regimen.

Recurrent pulmonary tuberculosis after treatment success: a population-based retrospective study in China

OBJECTIVES

Post-treatment recurrence remains a challenge for the global control of tuberculosis (TB). This study investigated longitudinal data on pulmonary TB recurrence rates and its risk factors among successfully treated smear-positive tuberculosis cases in China.

METHODS

From 1 January 2009 to 31 December 2016, we evaluated 33,441 treatment-naïve patients diagnosed with sputum smear-positive, non-multidrug-resistant TB in Hangzhou, China. We included the data of 9,828 patients with TB who were successfully treated.

RESULTS

A total of 4.9% were recurrent cases (479/9,828), identified within a median observation period lasting 1,565 days. Altogether, 51.1% (245/479) of the recurrences occurred within one year. The cumulative 2- and 5-year recurrence rates were 3.90% (95% confidence interval [CI], 3.3%-4.5%) and 5.4% (95% CI, 4.8%-6.0%), respectively. Prolonged treatment (over 7 months) was occurred in 64.7% (6,363/9,828), with median treatment duration of 242 (interquartile range, 195-348) days. Male sex (adjusted hazard ratio [aHR] [95% CI] = 1.61 [1.30-2.00], P<0.001), ≥ 60-years age (aHR [95% CI] = 2.03 [1.70-2.44], P<0.001), pulmonary cavity (aHR [95% CI] = 1.51 [1.25-1.82], P<0.001) and sputum positive at 2 months (aHR [95% CI] =1.39 [1.05-1.81], P=0.02) increased the risk of TB recurrence. Prolonged treatment was associated with reduced TB recurrence (aHR [95% CI] =0.73 [0.61-0.88], P=0.001).

CONCLUSIONS

Recurrence remains a problem for successfully treated patients with sputum smear-positive pulmonary TB, especially those with independent risk factors. Further analysis of prolonged treatment is required.

Personalized profiles of antioxidant signaling pathway in patients with tuberculosis

BACKGROUND/PURPOSE

The non-protein thiol glutathione is protective against infection by Mycobacterium tuberculosis (MTB) and, together with the transcription factor NRF2 (the nuclear factor erythroid 2-related factor 2), plays a crucial role in counteracting MTB-induced redox imbalance. Many genes implicated in the antioxidant response belong to the NRF2-signalling pathway, whose central role in the pathogenesis of tuberculosis (TB) has been recently proposed.

METHODS

In this study, we measured GSH levels in blood of patients with active TB and analysed the individual NRF2-mediated redox profile, in order to provide additional tools for discriminating the pathologic TB state and addressing therapeutic interventions.

RESULTS

Our findings show a systemic individual modulation of GSH and NRF2 signaling pathway in patients with TB, with a "personalized" induction of NRF2-target genes.

CONCLUSION

This study can provide useful tools to monitor the course of the infection and address patients' treatment.

Treatment effect measures for culture conversion endpoints in phase IIb tuberculosis treatment trials

Phase IIb trials of tuberculosis therapy rely on early biomarkers of treatment effect. Despite limited predictive ability for clinical outcomes, culture conversion, the event in which an individual previously culture positive for Mycobacterium tuberculosis yields a negative culture after initiating treatment, is a commonly used endpoint. Lack of consensus on how to define the outcome and corresponding measure of treatment effect complicates interpretation and limits between-trial comparisons. We review common analytic approaches to measuring treatment effect and introduce difference in restricted mean survival times as an alternative to identify faster times to culture conversion and express magnitude of effect on the time scale. Findings from the PanACEA MAMSTB trial are reanalyzed as an illustrative example. In a systematic review we demonstrate variability in analytic approaches, sampling strategies, and outcome definitions in phase IIb tuberculosis trials. Harmonization would allow for larger meta-analyses, and may help expedite advancement of new TB therapeutics.

Standard versus high dose of rifampicin in the treatment of pulmonary tuberculosis: a systematic review and meta-analysis

OBJECTIVES

A growing amount of evidence suggests that the rifampicin dosing currently recommended for tuberculosis treatment could be associated with inadequate exposure and unfavourable outcomes. We aimed to compare clinical and microbiological efficacy and safety outcomes of standard and higher rifampicin dosing.

METHODS

Data sources were MEDLINE, Google Scholar and the Cochrane Library. This was a systematic review and meta-analysis that included experimental or observational studies comparing 8-week sputum culture conversion, treatment failure, or safety outcomes in naïve patients with pulmonary tuberculosis treated with standard (10 mg/kg) or higher doses of rifampicin.

RESULTS

Of a total of 9683 citations screened, eight randomized controlled trials were included, accounting for 1897 subjects; the risk of bias was low in three studies, high in two and intermediate in three. At week 8 a higher proportion of patients in the high-dose group obtained a sputum culture conversion than those in the standard dose group (83.7% versus 80.6%, RR 1.06; 95%CI 1.01-1.12, p 0.028); this result was confirmed in the sub-analysis including patients treated with a rifampicin dose of ≥20 mg/kg, but not in those treated with 11-19 mg/kg. Events of treatment failure at end of treatment showed no significant difference between the two groups (RR 0.84; 95%CI 0.59-1.21, p 0.362). In the analysis evaluating safety outcome, the difference in the occurrence of a grade 3 or 4 liver toxicity or adverse drug reactions leading to discontinuation was not significant at the statistical analysis among the groups (7.2% versus 5.4%, RR 1.19; 95%CI 0.81-1.73, p 0.370, and 1.5% versus 0.6%, RR 2.31; 95%CI 0.65-8.21, p 0.195, respectively). No statistical heterogeneity among studies was observed for each outcome.

CONCLUSIONS

High doses of rifampicin were associated with an increased rate of sputum culture conversion at 8 weeks of treatment, particularly in patients receiving ≥20 mg/kg.

Old biomarkers in tuberculosis management: are they still useful? a systematic review

Introduction: The diagnosis of childhood tuberculosis (TB) can be challenging, given the lack of a gold standard test. Several new biomarkers have been studied for research purposes, but despite encouraging results, they are not used in clinical practice yet. Old biomarkers can be valuable tools in TB management. We conducted a systematic review to provide an update on their possible usefulness in TB patients.Areas covered: C-reactive protein could be useful to rule out TB, due to its high negative predictive value. Moreover, ferritin and erythrocyte sedimentation rates were found to be higher in TB patients with positive sputum smears. The lack of biomarkers decreases during an appropriate treatment course, indicating a poor response to treatment, seems to be correlated with a higher risk of death. Finally, procalcitonin and C-reactive protein seems to be useful in the differential diagnosis with pneumonia.Expert opinion: Old biomarkers are point-of-care tests, cheap and easily interpretable. These characteristics make them particularly useful, especially in TB endemic areas, to better manage patients with TB. Further studies performed in children are essential to implement the use of old biomarkers as diagnostic and prognostic tests.

Lack of Weight Gain During the First 2 Months of Treatment and Human Immunodeficiency Virus Independently Predict Unsuccessful Treatment Outcomes in Tuberculosis

BACKGROUND

Weight change may inform tuberculosis treatment response, but its predictive power may be confounded by human immunodeficiency virus (HIV).

METHODS

We prospectively followed up adults with culture-confirmed, drug-susceptible, pulmonary tuberculosis receiving standard 4-drug therapy (isoniazid, rifampin, pyrazinamide, and ethambutol) in Brazil. We examined median weight change 2 months after treatment initiation by HIV status, using quantile regression, and unsuccessful tuberculosis treatment outcome (treatment failure, tuberculosis recurrence, or death) by HIV and weight change status, using Cox regression.

RESULTS

Among 547 participants, 102 (19%) were HIV positive, and 35 (6%) had an unsuccessful outcome. After adjustment for confounders, persons living with HIV (PLWH) gained a median of 1.3 kg (95% confidence interval [CI], -2.8 to .1) less than HIV-negative individuals during the first 2 months of tuberculosis treatment. PLWH were at increased risk of an unsuccessful outcome (adjusted hazard ratio, 4.8; 95% CI, 2.1-10.9). Weight change was independently associated with outcome, with risk of unsuccessful outcome decreasing by 12% (95% CI, .81%-.95%) per 1-kg increase.

CONCLUSIONS

PLWH gained less weight during the first 2 months of tuberculosis treatment, and lack of weight gain and HIV independently predicted unsuccessful tuberculosis treatment outcomes. Weight, an easily collected biomarker, may identify patients who would benefit from alternative treatment strategies.

The effects of anti-inflammatory agents as host-directed adjunct treatment of tuberculosis in humans: a systematic review and meta-analysis

BACKGROUND

The potential role of adjunctive anti-inflammatory therapy to enhance tuberculosis (TB) treatment has recently received increasing interest. There is, therefore, a need to broadly examine current host-directed therapies (HDTs) that could accelerate treatment response and improve TB outcomes.

METHODS

This systematic review and meta-analysis included randomised controlled trials of vitamin D and other HDT agents in patients receiving antibiotic treatment for pulmonary TB. Sputum smear conversion rate at 4-8 weeks was the primary outcome. Secondary outcomes included blood indices associated with infectivity and inflammation, chest radiology and incidence of adverse events.

RESULTS

Fifty-five studies were screened for eligibility after the initial search, which yielded more than 1000 records. Of the 2540 participants in the 15 trials included in the meta-analysis, 1898 (74.7%) were male, and the age at entry ranged from 18 to 70 years. There was a 38% significantly (RR 1.38, 95% CI = 1.03-1.84) increased sputum smear negativity in patients administered with vitamin D in addition to standard TB treatment than those receiving only the TB treatment. Patients treated with other HDT anti-inflammatory agents in addition to TB treatment also had a 29% significantly increased sputum smear conversion rate (RR 1.29, 95% CI = 1.09-1.563). Lymphocyte to monocyte ratio was significantly higher in the vitamin D treatment groups compared to the controls (3.52 vs 2.70, 95% CI for difference 0.16-1.11, p = 0.009) and (adjusted mean difference 0.4, 95% CI 0.2 -- 0.6; p = 0.001); whilst tumour necrosis factor-alpha (TNF-α) showed a trend towards a reduction in prednisolone (p < 0.001) and pentoxifylline (p = 0.27) treatment groups. Vitamin D and N-acetylcysteine also accelerated radiographic resolution in treatment compared to placebo at 8 weeks. No differences were observed in the occurrence of adverse events among all HDT treatments.

CONCLUSIONS

Vitamin D and other anti-inflammatory HDT medications used as adjunct TB treatment may be well tolerated and effective. They significantly improved sputum smear conversion rate and chest radiological appearance, and also exhibited an inflammation resolution effect.

Leucine-rich alpha 2 glycoprotein is a new marker for active disease of tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is a global health problem. At present, prior exposure to Mtb can be determined by blood-based interferon-gamma release assay (IGRA), but active TB is not always detectable by blood tests such as CRP and ESR. This study was undertaken to investigate whether leucine-rich alpha-2 glycoprotein (LRG), a new inflammatory biomarker, could be used to assess active disease of TB. Cynomolgus macaques pretreated with or without Bacille Calmette-Guerin (BCG) vaccination were inoculated with Mtb to induce active TB. Blood was collected over time from these animals and levels of LRG as well as CRP and ESR were quantified. In the macaques without BCG vaccination, Mtb inoculation caused extensive TB and significantly increased plasma CRP and LRG levels, but not ESR. In the macaques with BCG vaccination, whereas Mtb challenge caused pulmonary TB, only LRG levels were significantly elevated. By immunohistochemical analysis of the lung, LRG was visualized in epithelioid cells and giant cells of the granulation tissue. In humans, serum LRG levels in TB patients were significantly higher than those in healthy controls and declined one month after anti-tubercular therapy. These findings suggest that LRG is a promising biomarker when performed following IGRA for the detection of active TB.

Survival analysis of patients with tuberculosis in Erbil, Iraqi Kurdistan region

BACKGROUND

Tuberculosis is an important health concern in Iraq, but limited research has examined the quality of tuberculosis care and the survival of the patients. This study aimed to assess the 12-month survival of tuberculosis patients and evaluate the effect of the associated risk factors on patients' survival.

METHODS

We reviewed the records of 728 patients with tuberculosis who were registered and treated at the Chest and Respiratory Disease Center in Erbil, Iraqi Kurdistan Region, from January 2012 to December 2017. Demographic data, the site of the disease, and treatment outcomes were retrieved from patients' records. Data analysis included the use of the Kaplan-Meier method and the log-rank test to calculate the estimates of the survival and assess the differences in the survival among the patients. The Cox regression model was used for univariate and multivariate analysis.

RESULTS

The mean period of the follow-up of the patients was 7.6 months. Of 728 patients with tuberculosis, 50 (6.9%) had died. The 12-month survival rate of our study was 93.1%. A statistically significant difference was detected in the survival curves of different age groups (P < 0.001) and the site of the disease (P = 0.012). In multivariate analysis, lower survival rates were only observed among patients aged ≥65 years (hazard ratio = 9.36, 95% CI 2.14-40.95) and patients with extrapulmonary disease (hazard ratio = 2.61, 95% CI 1.30-5.27).

CONCLUSION

The 12-month survival rate of tuberculosis patients managed at the Chest and Respiratory Disease Center in Erbil was similar to the international rates. The high rates of extrapulmonary tuberculosis and the low survival rate necessitate further studies and action with a possible revision to the tuberculosis management strategy.

Simultaneous 18F-FDG PET/MRI in tuberculous spondylitis: an independent method for assessing therapeutic response - case series

BACKGROUND

¹⁸F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) shows great potential for diagnosis and assessing therapeutic response of tuberculous spondylitis. Tuberculous spondylitis required long-term anti-tuberculosis (TB) medication therapy, and the optimal duration of therapy is controversial. There is still no clear way to tell when the anti-TB therapy can safely be discontinued.

CASE PRESENTATION

Three patients with tuberculous spondylitis were evaluated for therapeutic response using 18F-FDG PET/magnetic resonance imaging (MRI). Clinical and hematological improvements were achieved after about 12 months of anti-TB medication therapy, and we considered whether to discontinue the therapy. There was no relapse during one year of follow-up after discontinuation of 12 months anti-TB medication based on the low maximum standardized uptake value (SUV_max) of 1.83 in one patient. However, the other two patients continued further anti-TB medication therapy based on the high SUVmax of 4.14 and 7.02, which were suspected to indicate active residual lesions in the abscess or granulation tissues. Continuous TB was confirmed by the bacterial and histological examinations.

CONCLUSIONS

18F-FDG PET/MRI has metabolic and anatomical advantages for assessing therapeutic response in TB spondylitis, and can be considered as a helpful independent and alternative method for determining the appropriate time to discontinue anti-TB medication.

Prognostic value of the mitogen response in the interferon-γ release assay in patients with culture-confirmed tuberculosis

BACKGROUND

_The mitogen response in interferon-γ(IFN-γ) release assays(IGRAs) measures IFN-γ after binding to CD2, a surface adhesion marker found on T-cells and NK cells. A lower mitogen response implies either peripheral blood mononuclear cells have fewer adhesion molecules either in absolute numbers or per T-cells, or the pathway from adhesion molecules to IFN-γ production is not functioning well. To date, it remains poorly understood whether the mitogen response is associated with outcomes in tuberculosis patients.

METHODS

_From 2012 to 2017, patients with culture-confirmed tuberculosis were tested for QuantiFERON-TB Gold In-Tube(QFT-GIT). The associations between patient outcomes and QFT-GIT as well as IFN-γ responses to the mitogen were investigated. Outcomes of interest included 1-year mortality after tuberculosis diagnosis and 2-month culture conversion.

RESULTS

_In total, 466 culture-confirmed tuberculosis patients were enrolled and QFT-GIT was positive in 309(66%). Within 1 year of diagnosis, 20(4%) died and notably, 15(11%) out of 137 patients with a lower mitogen response did so. The multivariate Cox model showed that a lower mitogen response (hazard ratio, 8.789; 95% confidence interval, 3.074-25.129) was independently associated with 1-year mortality. Moreover, among 160 patients with smear-positive culture-confirmed pulmonary tuberculosis, multivariate logistic analysis indicated that a lower mitogen response (odds ratio, 3.966; 95% confidence interval, 1.182-13.303) was significantly associated with 2-month culture persistence.

CONCLUSIONS

_This study found that a lower mitogen response was associated with worse 1-year survival in tuberculosis patients and correlated with 2-month culture persistence in patients with sputum smear-positive culture-confirmed tuberculosis. These findings suggest another application of QFT-GIT for prognostication of tuberculosis patients.

A novel label-free electrochemical impedance aptasensor for highly sensitive detection of human interferon-gamma based on target-induced exonuclease inhibition

In this paper, a novel label-free electrochemical impedance aptasensor for highly sensitive detection of IFN-γ based on target-induced exonuclease inhibition was constructed. For this purpose, we designed a DNA hairpin modified on the gold electrode whose loop was the aptamer of the IFN-γ, and the stem was 5'-thiol-modified. In the absence of IFN-γ, Exonuclease III (Exo III) and Exonuclease I (Exo I) digested the double-stranded and single-stranded strands of the hairpin DNA, respectively, causing smaller impedance value on the surface of the electrode. In the presence of IFN-γ, the function of Exo III was greatly inhibited by the binding of the aptamer with the target, and it stopped after cutting three bases of the hairpin DNA. Forming a major target-bound aptamer digestion product, it could not be digested by Exo I, so there was larger impedance on the electrode surface. The calibration curve for IFN-γ was linear in the range of 1 pM-50 nM with the detection limit (LOD) of 0.7 pM_. The proposed aptasensor proved good selectivity and reproducibility, and low cost. In addition, the biosensor was able to detect IFN-γ in serum samples successfully, which is expected to provide an efficient method for TB diagnosis at early stages.

Increasing Number and Volume of Cavitary Lesions on Chest Computed Tomography Are Associated With Prolonged Time to Culture Conversion in Pulmonary Tuberculosis

Background

Cavitary lesions (CLs) primarily identified by chest x-ray (CXR) have been associated with worse clinical outcomes among patients with pulmonary tuberculosis (PTB). Chest computed tomography (CT), which has better resolution and increased sensitivity to detect lung abnormalities, has been understudied in PTB patients. We compared detection of CLs by CT and CXR and assessed their association with time to sputum culture conversion (tSCC).

Methods

This was a retrospective cohort study of 141 PTB patients who underwent CT. We used multivariate Cox proportional hazards models to evaluate the association between CLs on CXR and the number and single largest volume of CLs on CT with tSCC.

Results

Thirty (21%) and 75 (53%) patients had CLs on CXR and CT, respectively. CT detected cavities in an additional 44 patients (31%) compared with CXR. After multivariable adjustment, we observed a negative association between CLs and tSCC, with an adjusted hazard ratio (aHR) of 0.56 (95% confidence interval [CI], 0.32 to 0.97) for single CLs and 0.31 (95% CI, 0.16 to 0.60) for multiple CLs present on CT. Patients with a CL volume ≥25 mL had a prolonged tSCC (aHR, 0.39; 95% CI, 0.21 to 0.72). CLs on CXR were not associated with increased tSCC after multivariable adjustment.

Conclusions

CT detected a larger number of cavities in patients with PTB relative to CXR. We observed an association between increasing number and volume of CLs on CT and delayed tSCC independent of sputum microscopy result. Our findings highlight a potential role for CT in the clinical and research setting as a tool to risk-stratify patients with PTB.

Double prodrugs of a fosmidomycin surrogate as antimalarial and antitubercular agents

A series of eleven double prodrug derivatives of a fosmidomycin surrogate were synthesized and investigated for their ability to inhibit in vitro growth of P. falciparum and M. tuberculosis. A pivaloyloxymethyl (POM) phosphonate prodrug modification was combined with various prodrug derivatisations of the hydroxamate moiety. The majority of compounds showed activity comparable with or inferior to fosmidomycin against P. falciparum. N-benzyl substituted carbamate prodrug 6f was the most active antimalarial analog with an IC₅₀ value of 0.64 µM. Contrary to fosmidomycin and parent POM-prodrug 5, 2-nitrofuran and 2-nitrothiophene prodrugs 6i and 6j displayed promising antitubercular activities.

Drug resistance profile of Mycobacterium tuberculosis and predictors associated with the development of drug resistance

OBJECTIVES

Drug-resistant tuberculosis (DR-TB) is a major challenge to national TB control programmes in developing countries. In the Pakistan province of Punjab, the extent and development of DR-TB is not well known. The current study was therefore conducted to assess the incidence and predictors of DR-TB in Punjab Province.

METHODS

Drug susceptibility testing was performed for 863 confirmed culture-positive Mycobacterium tuberculosis isolates using the proportion method. Patients were enrolled in the Programmatic Management of Drug-Resistant TB Unit of Gulab Devi Chest Hospital (Lahore, Pakistan) from August 2011 to September 2013. Data analysis was performed using IBS SPSS Statistics v.20. Multivariate logistic regression analysis was performed to assess risk factors for DR-TB.

RESULTS

The rate of resistance to at least one drug (i.e. DR-TB) was 35.0% (302/863) and the rate of multidrug-resistant TB (MDR-TB) was 30.0% (259/863). Among DR-TB cases, the number of females was relatively higher (167/302; 55.3%) compared with males. The majority of DR-TB patients resided in a rural area (229/302; 75.8%). Significant predictors of DR-TB were age 18-45 years, previous TB treatment, rural residence, being a housewife, being married, duration of sickness >1year and unemployment.

CONCLUSION

The problem of DR-TB in Pakistan is significant. The strongest risk factors were young age and previous anti-TB treatment. Being married, being a housewife, rural residence and unemployment were also risk factors, culminating in an urgent need for effective control, early diagnosis and treatment policies for DR-TB.

Immunoscreening of the M. tuberculosis F15/LAM4/KZN secretome library against TB patients' sera identifies unique active- and latent-TB specific biomarkers

Tuberculosis (TB) protein biomarkers are urgently needed for the development of point-of-care diagnostics, new drugs and vaccines. Mycobacterium tuberculosis extracellular and secreted proteins play an important role in host-pathogen interactions. Antibodies produced against M. tuberculosis proteins before the onset of clinical symptoms can be used in proteomic studies to identify their target proteins. In this study, M. tuberculosis F15/LAM4/KZN strain phage secretome library was screened against immobilized polyclonal sera from active TB patients (n = 20), TST positive individuals (n = 15) and M. tuberculosis uninfected individuals (n = 20) to select and identify proteins recognized by patients' antibodies. DNA sequence analysis from randomly selected latent TB and active TB specific phage clones revealed 118 and 96 ORFs, respectively. Proteins essential for growth, virulence and metabolic pathways were identified using different TB databases. The identified active TB specific biomarkers included five proteins, namely, TrpG, Alr, TreY, BfrA and EspR, with no human homologs, whilst latent TB specific biomarkers included NarG, PonA1, PonA2 and HspR. Future studies will assess potential applications of identified protein biomarkers as TB drug or vaccine candidates/targets and diagnostic markers with the ability to discriminate LTBI from active TB.

IP-10 dried blood spots assay monitoring treatment efficacy in extrapulmonary tuberculosis in a low-resource setting

Treatment efficacy is difficult to evaluate in extrapulmonary tuberculosis (EPTB) patients. Interferon-γ inducible protein (IP-)10 has been suggested as a biomarker for response to treatment. We have investigated if IP-10 from dried plasma spots (DPS) or dried blood spots (DBS) can be used in treatment monitoring of EPTB patients in a low-resource setting of Zanzibar. IP-10 levels in plasma, DPS and DBS samples collected before, during (2 months) and after TB treatment of 36 EPTB patients (6 culture and/or Xpert MTB/RIF positive and 30 clinically diagnosed) and 8 pulmonary tuberculosis (PTB) patients, were quantified by an enzyme-linked immunosorbent assay. There was a high positive correlation between IP-10 measured in plasma and DPS and DBS, respectively. We found a significant decline in IP-10 levels from baseline to end of treatment in plasma, DPS and DBS, both in EPTB and PTB patients. The declines were observed already after 2 months in HIV negative patients. In conclusion, the DPS/DBS IP-10 assay allows for easy and manageable monitoring in low-resource settings and our findings suggest that IP-10 may serve as a biomarker for treatment efficacy in EPTB patients, albeit further studies in cohorts of patients with treatment failure and relapse are needed.

Analysis of the Antigenic Properties of Membrane Proteins of Mycobacterium tuberculosis

Tuberculosis (TB) is a continuing major threat to global health and a leading cause of death, particularly in developing countries. In this study, we aimed to identify a specific and sensitive diagnostic biomarker and develop a vaccine to prevent this disease. We investigated membrane proteins to reveal biomarkers in serum and peripheral blood mononuclear cells (PBMCs) obtained from TB patients. We employed Western blotting to evaluate serological immunoglobulin G levels, and Enzyme Linked Immunospot (ELISpot) to assess the antigen-specific cellular interferon-γ secretion from PBMCs after membrane protein stimulation. A total of 219 membrane proteins were identified, 52 exhibited at a higher levels than the 38-kDa prositive control. Of these 18 exhibited reacted ratios above 1, especially Rv1111c (427-981), with a ratios at 3.38. Accuracy and sensitivity were markedly higher for the top two antigen candidates, Rv0232 and Rv1115, after two rounds of ELISpot tests than ESAT-6 in the commercial kit (42.15 and 43.62%, respectively). These two proteins were administered to mice to detect whether they acted as effective antigens in vivo. These data provide a comprehensive view of the membranes involved in humoural and cellular immune responses that may be used as biomarkers for TB and candidates for a vaccine.

Biomarkers for tuberculosis: the case for lipoarabinomannan

Tuberculosis (TB) is considered the most onerous of infectious diseases according to recent reports from the World Health Organization. Available tests for TB diagnosis present severe limitations, and a reliable point-of-care (POC) diagnostic test does not exist. Neither is there a test to discern between the different stages of TB, and in particular to predict which patients with Mycobacterium tuberculosis infection and no clinical signs are more at risk of advancing to overt disease. We here review the usefulness of mycobacterial lipoarabinomannan (LAM) as a diagnostic marker for active and latent TB and, also, aspects of the immune response to LAM relevant to such tests. There is a high potential for urinary LAM-based POC tests for the diagnosis of active TB. Some technical challenges to optimised sensitivity of the test will be detailed. A method to quantify LAM in urine or serum should be further explored as a test of treatment effect. Recent data on the immune response to LAM suggest that markers for host response to LAM should be investigated for a prognostic test to recognise individuals at the greatest risk of disease activation.

There is a high potential for a urinary LAM-based point-of-care test to diagnose TB. Markers for host response to LAM should be explored to identify those at highest risk of developing active TB.http://ow.ly/FyCs30n4uFE

Macrophage mannose receptor, CD206, predict prognosis in patients with pulmonary tuberculosis

Tuberculosis (TB) remains a leading cause of fatal infectious disease. Accumulations of macrophages are found in infected sites; thus, we hypothesized that a marker of activated macrophages may be related to prognosis of pulmonary TB (PTB). This study investigated serum soluble macrophage mannose receptor, sCD206, in PTB and examined its clinical significance. First, the concentration of sCD206 was measured in the sera of 96 patients with PTB (Tenryu cohort), and in pleural effusions from 29 patients with TB pleurisy. These were verified in another independent cohort (Shizuoka cohort). We found increased concentrations of sCD206 in sera, but not in pleural effusions of PTB patients. Notably, PTB patients with poor prognosis showed significantly higher levels of serum sCD206. At a cut-off value of 1,600 ng/mL in the Tenryu cohort, sCD206 predicted prognosis of PTB with area under the curve 0.847, sensitivity 77.3%, and specificity 86.5%. These results were validated in the Shizuoka cohort. Pathological analyses showed concordance of enhanced CD206 expression in lung and pleural tissues with caseating granuloma in TB. Serum sCD206 increased in PTB and was associated with prognosis. sCD206 is a potential biomarker for PTB.

Delayed Sputum Culture Conversion in Tuberculosis-Human Immunodeficiency Virus-Coinfected Patients With Low Isoniazid and Rifampicin Concentrations

Background

The relationship between concentrations of antituberculosis drugs, sputum culture conversion, and treatment outcome remains unclear. We sought to determine the association between antituberculosis drug concentrations and sputum conversion among patients coinfected with tuberculosis and human immunodeficiency virus (HIV) and receiving first-line antituberculosis drugs.

Methods

We enrolled HIV-infected Ugandans with pulmonary tuberculosis. Estimation of first-line antituberculosis drug concentrations was performed 1, 2, and 4 hours after drug intake at 2, 8, and 24 weeks of tuberculosis treatment. Serial sputum cultures were performed at each visit. Time-to-event analysis was used to determine factors associated with sputum culture conversion.

Results

We enrolled 268 HIV-infected patients. Patients with low isoniazid and rifampicin concentrations were less likely to have sputum culture conversion before the end of tuberculosis treatment (hazard ratio, 0.54; 95% confidence interval, .37-.77; P = .001) or by the end of follow-up (0.61; .44-.85; P = .003). Patients in the highest quartile for area under the rifampicin and isoniazid concentration-time curves for were twice as likely to experience sputum conversion than those in the lowest quartile. Rifampicin and isoniazid concentrations below the thresholds and weight <55 kg were both risk factors for unfavorable tuberculosis treatment outcomes. Only 4.4% of the participants had treatment failure.

Conclusion

Although low antituberculosis drug concentrations did not translate to a high proportion of patients with treatment failure, the association between low concentrations of rifampicin and isoniazid and delayed culture conversion may have implications for tuberculosis transmission. Clinical Trials Registration: NCT01782950.

Robust Bayesian nonlinear mixed-effects modeling of time to positivity in tuberculosis trials

Early phase 2 tuberculosis (TB) trials are conducted to characterize the early bactericidal activity (EBA) of anti-TB drugs. The EBA of anti-TB drugs has conventionally been calculated as the rate of decline in colony forming unit (CFU) count during the first 14 days of treatment. The measurement of CFU count, however, is expensive and prone to contamination. Alternatively to CFU count, time to positivity (TTP), which is a potential biomarker for long-term efficacy of anti-TB drugs, can be used to characterize EBA. The current Bayesian nonlinear mixed-effects (NLME) regression model for TTP data, however, lacks robustness to gross outliers that often are present in the data. The conventional way of handling such outliers involves their identification by visual inspection and subsequent exclusion from the analysis. However, this process can be questioned because of its subjective nature. For this reason, we fitted robust versions of the Bayesian nonlinear mixed-effects regression model to a wide range of TTP datasets. The performance of the explored models was assessed through model comparison statistics and a simulation study. We conclude that fitting a robust model to TTP data obviates the need for explicit identification and subsequent "deletion" of outliers but ensures that gross outliers exert no undue influence on model fits. We recommend that the current practice of fitting conventional normal theory models be abandoned in favor of fitting robust models to TTP data.

Modelling of mycobacterial load reveals bedaquiline's exposure-response relationship in patients with drug-resistant TB

Background

Bedaquiline has been shown to reduce time to sputum culture conversion (SCC) and increase cure rates in patients with drug-resistant TB, but the influence of drug exposure remains uncharacterized.

Objectives

To investigate whether an exposure–response relationship could be characterized by making better use of the existing information on pharmacokinetics and longitudinal measurements of mycobacterial load.

Methods

Quantitative culture data in the form of time to positivity (TTP) in mycobacterial growth indicator tubes obtained from a randomized placebo-controlled Phase IIb registration trial were examined using non-linear mixed-effects methodology. The link to individual bedaquiline exposures and other patient characteristics was evaluated.

Results

The developed model included three simultaneously fitted components: a longitudinal representation of mycobacterial load in patients, a probabilistic component for bacterial presence in sputum samples, and a time-to-event model for TTP. Data were described adequately, and time to SCC was well predicted. Individual bedaquiline exposure was found to significantly affect the decline in mycobacterial load. Consequently, the proportion of patients without SCC at week 20 is expected to decrease from 25% (95% CI 20%–31%) without bedaquiline to 17% (95% CI 13%–21%), 12% (95% CI 8%–16%) and 7% (95% CI 4%–11%), respectively, with half the median, median and double the median bedaquiline exposure observed in patients with standard dosing. Baseline bacterial load and level of drug resistance were other important predictors.

Conclusions

To our knowledge, this is the first successful description of bedaquiline’s exposure–response relationship and may be used when considering dose optimization. Characterization of this relationship was possible by integrating quantitative information in existing clinical data using novel models.

High Frequencies of Caspase-3 Expressing Mycobacterium tuberculosis-Specific CD4+ T Cells Are Associated With Active Tuberculosis

Antigen-specific CD4⁺ T cell responses to Mycobacterium tuberculosis (Mtb) infection are important for host defense against tuberculosis (TB). However, Mtb-specific IFN-γ-producing T cells do not distinguish active tuberculosis (ATB) patients from individuals with asymptomatic latent Mtb infection (LTBI). We reasoned that the immune phenotype of Mtb-specific IFN-γ⁺CD4⁺ T cells could provide an indirect gauge of Mtb antigen load within individuals. We sought to identify immune markers in Mtb-specific IFN-γ⁺CD4⁺ T cells and hypothesized that expression of caspase-3 Mtb-specific CD4⁺ T cells would be associated with ATB. Using polychromatic flow cytometry, we evaluated the expression of caspase-3 in Mtb-specific CD4⁺ T cells from LTBI and ATB as well as from ATB patients undergoing anti-TB treatment. We found significantly higher frequencies of Mtb-specific caspase-3⁺IFN-γ⁺CD4⁺ T cells in ATB compared to LTBI. Caspase-3⁺IFN-γ⁺CD4⁺ T cells were also more activated compared to their caspase-3-negative counterparts. Furthermore, the frequencies of caspase-3⁺IFN-γ⁺CD4⁺ T cells decreased in response to anti-TB treatment. Our studies suggest that the frequencies of caspase-3-expressing antigen-specific CD4⁺ T cells may reflect mycobacterial burden in vivo and may be useful for distinguishing Mtb infection status along with other host biomarkers.

Urine IP-10 as a biomarker of therapeutic response in patients with active pulmonary tuberculosis

Background

Prior to clinical trials of new TB drugs or therapeutic vaccines, it is necessary to develop monitoring tools to predict treatment outcomes in TB patients. Urine interferon gamma inducible protein 10 (IP-10) is a potential biomarker of treatment response in chronic hepatitis C virus infection and lung diseases, including tuberculosis. In this study, we assessed IP-10 levels in urine samples from patients with active TB at diagnosis, during treatment, and at completion, and compared these with levels in serum samples collected in parallel from matched patients to determine whether urine IP-10 can be used to monitor treatment response in patients with active TB.

Methods

IP-10 was measured using enzyme-linked immunosorbent assays in urine and serum samples collected concomitantly from 23 patients with active TB and 21 healthy adults (44 total individuals). The Mann-Whitney U test and Wilcoxon matched-pairs signed rank test were used for comparisons among healthy controls and patients at three time points, and LOESS regression was used for longitudinal data.

Results

The levels of IP-10 in urine increased significantly after 2 months of treatment (P = 0.0163), but decreased by the completion of treatment (P = 0.0035). Serum IP-10 levels exhibited a similar trend, but did not increase significantly after 2 months of treatment in patients with active TB.

Conclusions

Unstimulated IP-10 in urine can be used as a biomarker to monitor treatment response in patients with active pulmonary TB.

Modalities to monitor the treatment response in tuberculosis

Considering the global epidemic of drug resistance in Mycobacterium tuberculosis, early and accurate diagnosis as well as prompt initiation of antitubercular therapy (ATT) forms the mainstay of tuberculosis control programs. Patients on ATT may develop treatment failure due to diverse reasons including emergence of drug resistance in the host during the course of therapy. Monitoring the timely response to treatment in such cases has a significant role in rapid identification of drug resistant strains and institution of change of regimen to further decrease the morbidity and mortality associated with the disease. Furthermore, availability of faster surrogate end points to assess treatment efficacy, disease activity, cure, and relapse is one of the crucial requirements for undertaking innovative clinical trials related to TB. The article presents here the compilation of currently available methods for monitoring the treatment response in pulmonary as well as extrapulmonary TB.

Impact of smoking on sputum culture conversion and pulmonary tuberculosis treatment outcomes in Brazil: a retrospective cohort study

OBJECTIVE

To evaluate the impact of smoking on pulmonary tuberculosis (PTB) treatment outcomes and the two-month conversion rates for Mycobacterium tuberculosis sputum cultures among patients with culture-confirmed PTB in an area with a moderate incidence of tuberculosis in Brazil.

METHODS

This was a retrospective cohort study of PTB patients diagnosed and treated at the Thoracic Diseases Institute of the Federal University of Rio de Janeiro between 2004 and 2012.

RESULTS

Of the 298 patients diagnosed with PTB during the study period, 174 were included in the outcome analysis: 97 (55.7%) were never-smokers, 31 (17.8%) were former smokers, and 46 (26.5%) were current smokers. Smoking was associated with a delay in sputum culture conversion at the end of the second month of TB treatment (relative risk = 3.58 &091;95% CI: 1.3-9.86&093;; p = 0.01), as well as with poor treatment outcomes (relative risk = 6.29 &091;95% CI: 1.57-25.21&093;; p = 0.009). The association between smoking and a positive culture in the second month of treatment was statistically significant among the current smokers (p = 0.027).

CONCLUSIONS

In our sample, the probability of a delay in sputum culture conversion was higher in current smokers than in never-smokers, as was the probability of a poor treatment outcome.

Comparison of Sputum-Culture Conversion for Mycobacterium bovis and M. tuberculosis

Current US guidelines recommend longer treatment for tuberculosis (TB) caused by pyrazinamide-resistant organisms (e.g., Mycobacterium bovis) than for M. tuberculosis TB. We compared treatment response times for patients with M. bovis TB and M. tuberculosis TB reported in the United States during 2006–2013. We included culture-positive, pulmonary TB patients with genotyping results who received standard 4-drug treatment at the time of diagnosis. Time to sputum-culture conversion was defined as time between treatment start date and date of first consistently culture-negative sputum. We analyzed 297 case-patients with M. bovis TB and 30,848 case-patients with M. tuberculosis TB. After 2 months of treatment, 71% of M. bovis and 65% of M. tuberculosis TB patients showed conversion of sputum cultures to negative. Likelihood of culture conversion was higher for M. bovis than for M. tuberculosis, even after controlling for treatment administration type, sex, and a composite indicator of bacillary burden.

Potential of High-Affinity, Slow Off-Rate Modified Aptamer Reagents for Mycobacterium tuberculosis Proteins as Tools for Infection Models and Diagnostic Applications

Direct pathogen detection in blood to diagnose active tuberculosis (TB) has been difficult due to low levels of circulating antigens or due to the lack of specific, high-affinity binding reagents and reliable assays with adequate sensitivity. We sought to determine whether slow off-rate modified aptamer (SOMAmer) reagents with subnanomolar affinity for Mycobacterium tuberculosis proteins (antigens 85A, 85B, 85C, GroES, GroEL2, DnaK, CFP10, KAD, CFP2, RplL, and Tpx) could be useful to diagnose tuberculosis. When incorporated into the multiplexed, array-based proteomic SOMAscan assay, limits of detection reached the subpicomolar range in 40% serum. Binding to native M. tuberculosis proteins was confirmed by using M. tuberculosis culture filtrate proteins and fractions from infected macrophages and via affinity capture assays and subsequent mass spectrometry. Comparison of serum from culture-positive pulmonary TB patients and TB suspects systematically ruled out for TB revealed small but statistically significant (P < 0.0001) differences in the median M. tuberculosis signals and in specific pathogen markers, such as antigen 85B. Samples where many M. tuberculosis aptamers produced high signals were rare exceptions. In concentrated, protein-normalized urine from TB patients and non-TB controls, the CFP10 (EsxB) SOMAmer yielded the most significant differential signals (P < 0.0276), particularly in TB patients with HIV coinfection. In conclusion, direct M. tuberculosis antigen detection proved difficult even with a sensitive method such as SOMAscan, likely due to their very low, subpicomolar abundance. The observed differences between cases and controls had limited diagnostic utility in serum and urine, but further evaluation of M. tuberculosis SOMAmers using other platforms and sample types is warranted.

Mycobacterium tuberculosis Induction of Heme Oxygenase-1 Expression Is Dependent on Oxidative Stress and Reflects Treatment Outcomes

The antioxidant enzyme heme oxygenase-1 (HO-1) is implicated in the pathogenesis of tuberculosis (TB) and has been proposed as a biomarker of active disease. Nevertheless, the mechanisms by which Mycobacterium tuberculosis (Mtb) induces HO-1 as well as how its expression is affected by HIV-1 coinfection and successful antitubercular therapy (ATT) are poorly understood. We found that HO-1 expression is markedly increased in rabbits, mice, and non-human primates during experimental Mtb infection and gradually decreased during ATT. In addition, we examined circulating concentrations of HO-1 in a cohort of 130 HIV-1 coinfected and uninfected pulmonary TB patients undergoing ATT to investigate changes in expression of this biomarker in relation to HIV-1 status, radiological disease severity, and treatment outcome. We found that plasma levels of HO-1 were elevated in untreated HIV-1 coinfected TB patients and correlated positively with HIV-1 viral load and negatively with CD4⁺ T cell count. In both HIV-1 coinfected and Mtb monoinfected patients, HO-1 levels were substantially reduced during successful TB treatment but not in those who experienced treatment failure or subsequently relapsed. To further delineate the molecular mechanisms involved in induction of HO-1 by Mtb, we performed a series of in vitro experiments using mouse and human macrophages. We found that Mtb-induced HO-1 expression requires NADPH oxidase-dependent reactive oxygen species production induced by the early-secreted antigen ESAT-6, which in turn triggers nuclear translocation of the transcription factor NRF-2. These observations provide further insight into the utility of HO-1 as a biomarker of both disease and successful therapy in TB monoinfected and HIV-TB coinfected patients and reveal a previously undocumented pathway linking expression of the enzyme with oxidative stress.

Treatment Outcomes of Patients Treated for Pulmonary Tuberculosis after Undergoing Gastrectomy

Gastrectomy is a proxy of malnutrition, which may lead to increased risk for developing pulmonary tuberculosis (TB). Malabsorption in gastrectomy patients could lead to low serum levels of rifampicin, which may be related to higher treatment failure. However, there is limited information on treatment outcomes of TB in patients who have undergone gastrectomy. This study aims to determine treatment outcomes and adverse effects in patients treated for TB after undergoing gastrectomy for gastric cancer. During the study period, 112 patients were treated for active TB that developed after gastrectomy for gastric cancer. Among them, we selected 15 patients who were culture positive at initial diagnosis and had evidence of active TB on imaging studies; namely, the remaining 97 patients without initial culture or imaging studies were excluded. We thus performed a case-control study of gastric cancer patients treated for TB after undergoing gastrectomy (n = 15). The control group was defined as age- and sex-matched TB patients who had not received gastrectomy (n = 45). Treatment failure in clinical, microbiological aspects, and adverse events were analyzed. Patients who had undergone gastrectomy exhibited higher 4-month clinical failure rates, compared to non-gastrectomy patient: 4 (26.7%) vs. 1 (2.2%), P = 0.012. Gastrointestinal adverse effects were more frequent in patients with gastrectomy, compared to non-gastrectomy patients: 9 (60%) vs. 5 (11.1%), P < 0.001. In conclusion, patients treated for TB after undergoing gastrectomy are associated with higher rates of gastrointestinal adverse events and treatment failure.

Early interventions for diabetes related tuberculosis associate with hastened sputum microbiological clearance in Virginia, USA

Background

Diabetes complicates tuberculosis (TB) treatment including a prolonged time of sputum culture conversion to negative growth. Since 2013 in Virginia, interventions early in the treatment course have used therapeutic drug monitoring and dose correction for isoniazid and rifampin after 2 weeks of TB treatment in patients with diabetes along with nurse manager initiated diabetes education and linkage to care.

Methods

A retrospective cohort study of the state TB registry was performed for patients initiating drug-susceptible pulmonary TB treatment that were matched for age, gender, chest imaging and sputum smear status to compare time to sputum culture conversion and other clinical outcomes in the pre-and post-intervention groups.

Results

Three hundred sixty-three patients had documented time to sputum culture conversion in the pre-and post-intervention periods, including 56 (15%) with diabetes. Seventy-four (57%) of all patients with diabetes were ≥60 years of age at treatment initiation. Twenty-six patients with diabetes were matched in each group. Mean time to sputum culture conversion in the post-intervention group was 42 ± 22 days compared to the pre-intervention group of 62 ± 31 days (p = 0.01). In the post-intervention group 21 (80%) of patients with diabetes had culture conversion by 2 months compared to 13 (50%) in the pre-intervention group (p = 0.04).

Conclusions

Early interventions for diabetes related TB in the programmatic setting may hasten sputum culture conversion.

Biomarkers of Infectious Diseases

Infection is defined as a pathologic process caused by the invasion of normally sterile tissue or fluid or body cavity by pathogenic or potentially pathogenic microorganisms. Sepsis is defined as the presence of organ dysfunction occurring as the result of a dysregulated host response to an infection.

BLR1 and FCGR1A transcripts in peripheral blood associate with the extent of intrathoracic tuberculosis in children and predict treatment outcome

Biomarkers reflecting the extent of Mycobacterium tuberculosis-induced pathology and normalization during anti-tuberculosis treatment (ATT) would considerably facilitate trials of new treatment regimens and the identification of patients with treatment failure. Therefore, in a cohort of 99 Indian children with intrathoracic tuberculosis (TB), we performed blood transcriptome kinetic analysis during ATT to explore 1) the association between transcriptional biomarkers in whole blood (WB) and the extent of TB disease at diagnosis and treatment outcomes at 2 and 6 months, and 2) the potential of the biomarkers to predict treatment response at 2 and 6 months. We present the first data on the association between transcriptional biomarkers and the extent of TB disease as well as outcome of ATT in children: Expression of three genes down-regulated on ATT (FCGR1A, FPR1 and MMP9) exhibited a positive correlation with the extent of TB disease, whereas expression of eight up-regulated genes (BCL, BLR1, CASP8, CD3E, CD4, CD19, IL7R and TGFBR2) exhibited a negative correlation with the extent of disease. Baseline levels of these transcripts displayed an individual capacity >70% to predict the six-month treatment outcome. In particular, BLR1 and FCGR1A seem to have a potential in monitoring and perhaps tailoring future antituberculosis therapy.

Neopterin and oxidative stress markers in the diagnosis of extrapulmonary tuberculosis

BACKGROUND

Extrapulmonary tuberculosis (EPTB) often presents with nonspecific signs and symptoms. Further the paucibacillary nature of extrapulmonary specimens and irregular distribution of bacilli lower the sensitivity of conventional diagnostic methods making EPTB, a diagnostic dilemma.

OBJECTIVE

To study neopterin, protein carbonyl and malondialdehyde (MDA) in EPTB.

METHODS

Sixty nine clinically confirmed cases with an equal number of age and sex matched healthy controls were enrolled. Ziehl-Neelsen staining for acid fast bacilli and culture on Lowenstein-Jensen medium were performed on all the extrapulmonary specimens. Serum neopterin and protein carbonyl levels were estimated using commercial ELISA kits. Malondialdehyde was determined by measuring thiobarbituric acid reactive substances.

RESULTS

Serum neopterin, protein carbonyl and MDA levels were significantly discriminative for cases of EPTB from healthy controls (p < 0.05). Levels of all the three biomarkers under study significantly differed between culture as well as smear positive and negative cases. A positive correlation between neopterin and protein carbonyl was seen among the cases.

CONCLUSIONS

So far few studies have integrated combination of validated host biomarkers for active disease in EPTB. Our study suggests the potential diagnostic role of neopterin, protein carbonyl and MDA in EPTB.