Dynamics of sputum conversion during effective tuberculosis treatment: A systematic review and meta-analysis

Early Microbiologic Markers of Pulmonary Tuberculosis Treatment Outcomes

Rationale: Earlier biomarkers of pulmonary tuberculosis (PTB) treatment outcomes are critical to monitor shortened anti-TB treatment (ATT). Objectives: To identify early microbiologic markers of unfavorable TB treatment outcomes. Methods: We performed a subanalysis of 2 prospective TB cohort studies conducted from 2013 to 2019 in India. We included participants aged ⩾18 years who initiated 6-month ATT for clinically or microbiologically diagnosed drug-sensitive PTB and completed at least one follow-up visit. Sputum specimens were subjected to a baseline Xpert Mycobacterium tuberculosis/rifampin (MTB/RIF) assay, acid-fast bacilli (AFB) microscopy and liquid and solid cultures, and serial AFB microscopy and liquid and solid cultures at weeks 2, 4, and 8. Poisson regression was used to assess the impact of available microbiologic markers (test positivity, smear grade, time to detection, and time to conversion) on a composite outcome of failure, recurrence, or death by 18 months after the end of treatment. Models were adjusted for age, sex, nutritional status, diabetes, smoking, alcohol consumption, and regimen type. Results: Among 1,098 eligible cases, there were 251 (22%) adverse TB treatment outcomes: 127 (51%) treatment failures, 73 (29%) recurrences, and 51 (20%) deaths. The primary outcome was independently associated with the Xpert MTB/RIF assay (medium-positive adjusted incidence rate ratio [aIRR], 1.91; 95% confidence interval [CI], 1.07-3.40; high-positive aIRR, 2.51; 95% CI, 1.41-4.46), positive AFB smear (aIRR, 1.48; 95% CI, 1.06-2.06), and positive liquid culture (aIRR, 1.98; 95% CI, 1.21-3.23) at baseline; Week 2 positive liquid culture (aIRR, 1.47; 95% CI, 1.04-2.09); and Week 8 positive AFB smear (aIRR, 1.63; 95% CI, 1.06-2.50) and positive liquid culture (aIRR, 1.54; 95% CI, 1.07-2.22). There was no evidence of Mycobacterium tuberculosis growth in the Mycobacterium Growth Indicator Tube at Week 4 conferring a higher risk of adverse outcomes (aIRR, 1.25; 95% CI, 0.89-1.75). Conclusions: Our analysis identifies Week 2 respiratory mycobacterial culture as the earliest microbiologic marker of unfavorable PTB treatment outcomes.

Cutaneous tuberculosis. Part II: Complications, diagnostic workup, histopathologic features, and treatment

Despite the availability of effective treatment regimens for cutaneous tuberculosis, challenges to disease control result from delayed diagnosis, infection with multidrug-resistant mycobacterial strains, and coinfection with HIV. Delayed diagnosis can be mitigated when dermatologists are sensitized to the clinical signs and symptoms of infection and by the incorporation of appropriate diagnostic tests. All cases of cutaneous tuberculosis should be confirmed with histopathology and culture with or without molecular testing. In each case, a thorough evaluation for systemic involvement is necessary. Mycobacteria may not be isolated from cutaneous tuberculosis lesions and therefore, a trial of antituberculosis treatment may be required to confirm the diagnosis. The second article in this 2-part continuing medical education series describes the sequelae, histopathology, and treatment of tuberculosis.

Proteomic analyses of smear-positive/negative tuberculosis patients uncover differential antigen-presenting cell activation and lipid metabolism

Background

Tuberculosis (TB) remains a major global health concern, ranking as the second most lethal infectious disease following COVID-19. Smear-Negative Pulmonary Tuberculosis (SNPT) and Smear-Positive Pulmonary Tuberculosis (SPPT) are two common types of pulmonary tuberculosis characterized by distinct bacterial loads. To date, the precise molecular mechanisms underlying the differences between SNPT and SPPT patients remain unclear. In this study, we aimed to utilize proteomics analysis for identifying specific protein signatures in the plasma of SPPT and SNPT patients and further elucidate the molecular mechanisms contributing to different disease pathogenesis.

Methods

Plasma samples from 27 SPPT, 37 SNPT patients and 36 controls were collected and subjected to TMT-labeled quantitative proteomic analyses and targeted GC-MS-based lipidomic analysis. Ingenuity Pathway Analysis (IPA) was then performed to uncover enriched pathways and functionals of differentially expressed proteins.

Results

Proteomic analysis uncovered differential protein expression profiles among the SPPT, SNPT, and Ctrl groups, demonstrating dysfunctional immune response and metabolism in both SPPT and SNPT patients. Both groups exhibited activated innate immune responses and inhibited fatty acid metabolism, but SPPT patients displayed stronger innate immune activation and lipid metabolic inhibition compared to SNPT patients. Notably, our analysis uncovered activated antigen-presenting cells (APCs) in SNPT patients but inhibited APCs in SPPT patients, suggesting their critical role in determining different bacterial loads/phenotypes in SNPT and SPPT. Furthermore, some specific proteins were detected to be involved in the APC activation/acquired immune response, providing some promising therapeutic targets for TB.

Conclusion

Our study provides valuable insights into the differential molecular mechanisms underlying SNPT and SPPT, reveals the critical role of antigen-presenting cell activation in SNPT for effectively clearing the majority of Mtb in bodies, and shows the possibility of APC activation as a novel TB treatment strategy.

Evaluation of drug-resistant tuberculosis treatment outcome in Limpopo province, South Africa

BACKGROUND

South Africa has the second-highest tuberculosis (TB) incidence globally. Drug-resistant TB (DR-TB) treatment has less successful treatment outcomes as compared with susceptible TB, and it hinders TB control and management programmes.

AIM

This study aimed to evaluate drug-resistant TB treatment outcomes and factors associated with successful treatment outcomes.

SETTING

The study was conducted in five districts in Limpopo province.

METHODS

The study design was retrospective and descriptive. Patients' demographic data, data on clinical characteristics and treatment outcomes data were extracted from the electronic drug-resistant tuberculosis register (EDRWeb) database system for the period, 2010-2018, in Limpopo province. Frequency, percentages and bivariate and multivariate logistic regression were used to analyse data using Statistical Package for Social Sciences version 27.0. The significance difference was determined at a 95% confidence interval and p 0.05.

RESULTS

A total of 385 drug-resistant records were included in this study. The treatment success rate was 223 (57.9%). A total of 197 (51.2%) patients were cured, 26 (6.8%) completed treatment, 19 (4.9%) treatment failure, 62 (16.1%) died, 78 (20.6%) were recorded as the loss to follow-up, 1 (0.3%) moved to another country and 2 (0.5%) were transferred out.

CONCLUSION

The treatment success rate was 57.9%, which is still below targets set by National Strategic Plan in South Africa and World Health Organization End TB targets.Contribution: The findings of the study reveal that to achieve successful DR-TB control programme and attain End TB targets, monitoring of treatment outcomes is crucial.

Time to Sputum Culture Conversion and Its Predictors Among Multidrug Resistant Tuberculosis Patients in Tigray, Northern Ethiopia: Retrospective Cohort Study

Background

Sputum culture conversion status is a cardinal index of treatment response and patient outcome for MDR TB patients on longer anti-TB drugs. But, there is limited information on time to sputum culture conversion of MDR TB patients on a longer anti-TB treatment regimen. Therefore, this study aimed to evaluate time to sputum culture conversion and its predictors among MDR TB patients in Tigray, Northern Ethiopia.

Methods

A retrospective cohort study was conducted from January 2017 through September 2020 among MDR TB patients in Tigray, Northern Ethiopia. Demographic and clinical characteristics including bacteriological data were extracted from the TB registration book and electronic database in Tigray Health Research Institute. Statistical analysis was performed using SPSS version 25. The time to initial sputum culture conversion was analyzed using the Kaplan-Meier method. Bivariate and multivariate Cox proportional hazards regression analyses were used to identify predictors for culture conversions. P <0.05 was considered statistically significant.

Results

A total of 294 eligible study participants with a median age of 30 years (IQR: 22.75-40) were included. The participants were followed for a total of 1066.7 person months. Sputum culture conversion was achieved in 269 (91%) of the study participants. The median time of sputum culture conversion was 64 days (IQR: 49-86). In our multivariate model, HIV-positive (aHR=1.529, 95% CI: 1.096-2.132, P=0.012), patients new to anti-TB treatment (aHR=2.093, 95% CI: 1.100-3.982, P=0.024) and baseline AFB smear grading of +1 (aHR=1.982, 95% CI: 1.428-2.750, P=0.001) significantly affected time to initial sputum culture conversion.

Conclusion

The median time of culture conversion was 64 days. Moreover, the majority of the study participants achieved culture conversion within the first six months of treatment commencement, which supports predefined standard treatment durations.

Use of light-emitting diode fluorescence microscopy to detect acid-fast bacilli in sputum as proficient alternative tool in the diagnosis of pulmonary tuberculosis in countries with limited resource settings

Background

Despite recent advances in the development of more sensitive technologies for the diagnosis of tuberculosis (TB), in resource-limited settings, the diagnosis continues to rely on sputum smear microscopy. This is because smear microscopy is simple, cost-efficient and the most accessible tool for the diagnosis of TB. Our study evaluated the performance of light-emitting diode fluorescence microscopy (LED-FM) using auramine/rhodamine (auramine) and the fluorescein di-acetate (FDA) vital stain in the diagnostic of pulmonary TB in Bamako, Mali.

Methods

Sputum smear microscopy was conducted using the FDA and auramine/rhodamine staining procedures on fresh samples using LED-FM to evaluate the Mycobacterium TB (MTB) metabolic activity and to predict contagiousness. Mycobacterial culture assay was utilized as a gold standard method.

Results

Out of 1401 TB suspected patients, 1354 (96.65%) were retrieved from database, which were MTB complex culture positive, and 47 (3.40%) were culture negative (no mycobacterial growth observed). Out of the 1354 included patients, 1343 (95.86%), were acid-fast bacillus (AFB) positive after direct FDA staining, 1352 (96.50%) AFB positive after direct Auramine, and 1354 (96.65%) AFB positive with indirect auramine after digestion and centrifugation. Overall, the FDA staining method has a sensitivity of 98.82%, while the sensitivity of Auramine with direct observation was 99.48%, and 99.56% with the indirect examination.

Conclusion

This study showed that, using fresh sputum both auramine/rhodamine and FDA are highly sensitive methods in diagnosing pulmonary TB and could be easily used in countries with limited resource settings.

Whole-Genome Sequencing of Clinical Isolates of Mycobacterium tuberculosis Isolated before and after Treatment

Mycobacterium tuberculosis clinical isolates CN177_0W, CN177_2W, CB060_0W, and CB060_2W were isolated from two tuberculosis patients in South Korea. Here, we report the whole-genome sequences of clinical isolates of M. tuberculosis isolated before and after tuberculosis treatment.

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.

High Pretreatment Level of Neutrophil to Lymphocyte Ratio, Monocyte to Lymphocyte Ratio and Other Factors Associated with Delayed Sputum Conversion in Patients with Pulmonary Tuberculosis

Introduction

Patients with delayed intensive phase sputum conversion have a higher risk of multidrug resistant-tuberculosis (MDR-TB) and poorer treatment outcomes. Both, host (immune response and comorbidity) and pathogen factors play important roles in determining sputum conversion after treatment initiation. Impaired host immune response, especially the cellular components, as defined by the increased pre-treatment level of neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) and other additional factors, were associated with severe active TB.

Purpose

To evaluate whether impaired immune responses (high pre-treatment level of NLR and MLR) and other factors associate with delayed sputum conversion at the end of the intensive phase treatment.

Patients and Methods

This was a case–control study from 2016 to 2020, which retrospectively analyzed the pre-treatment level of NLR, MLR and other factors among patients with new cases of pulmonary tuberculosis (PTB).

Results

A total of 62 patients (31 cases and 31 control). The cut-off value of high pretreatment level of NLR and MLR was 5.065 and 0.585, respectively. Bivariate analysis showed that pretreatment NLR ≥5.065 (OR 8.23, CI 95% 2.48–27.32, p < 0.001), MLR ≥0.585 (OR 10.18, 95% CI 3.13–33.18, p < 0.001) and BMI <18.5 (OR 2.91, 95% CI 1.03–8.20, p = 0.041) were associated with an increased risk of delayed sputum conversion. Multivariate analysis, however, showed that pretreatment NLR ≥5.065 was not significantly associated with delayed sputum conversion (AOR 3.370, 95% CI 0.71–15.91, p value 0.125). A high pretreatment of MLR (AOR 30.802, 95% CI 3.22–287.55, p value 0.003) and lower BMI (AOR 10.942, 95% CI 1.121–98.563, p value 0.033) were significantly associated with an increased risk of delayed intensive phase sputum conversion.

Conclusion

High MLR pretreatment and a low BMI were significantly associated with an increased risk of delayed sputum conversion at the end of the PTB intensive phase treatment. High NLR pretreatment, smoking, diabetes, and HIV were not associated with sputum conversion.