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.

Effect of sputum quality and role of Xpert® MTB/ RIF assay for detection of smear-negative pulmonary tuberculosis in same-day diagnosis strategy in Addis Ababa, Ethiopia

Background

There is limited information on the performance of the Xpert® MTB/RIF test for diagnosis of smear-negative pulmonary tuberculosis (SNPT) and rifampicin resistance (RR) in the same-day diagnosis approach. The effects of sputum quality and other factors affecting the Xpert performance are also under-investigated.

Objective

This study aimed to determine the performance of the Xpert® MTB/RIF test for detection of SNPT and RR in the same-day diagnosis strategy and the effect of sputum quality and other factors on its performance.

Methods

A cross-sectional study was conducted from August 2017 to January 2018 across 16 health facilities in Addis Ababa, Ethiopia. Two spot sputum samples were collected from 418 presumptive SNPT patients, tested with Xpert® MTB/RIF, then compared to tuberculosis culture. Additionally, culture isolates were tested for RR by BACTEC MGIT™ 960 drug susceptibility testing (DST) and MTBDRplus version 2.

Results

The Xpert® MTB/RIF test detected 24 (5.7%) SNPT cases, with a sensitivity of 92.3% (75.9% - 97.9%) and specificity of 99.2% (97.8% - 99.7%) compared with tuberculosis culture. Xpert® MTB/RIF also detected three (11.58%) RR strains with 100.0% concordance with BACTEC MGIT™ 960 DST and MTBDRplus results. Three blood-stained SNPT samples were positive by Xpert (30.0%), which was 6.9 times higher compared to salivary sputum (odds ratio: 6.9, 95% confidence interval: 1.36-34.96, p = 0.020).

Conclusion

The performance of the Xpert® MTB/RIF to detect SNPT and RR in same-day diagnosis is high. However, SNPT positivity varies among sputum qualities, and good sample collection is necessary for better test performance.

A new droplet digital PCR assay: improving detection of paucibacillary smear-negative pulmonary tuberculosis

BACKGROUND

Smear-negative pulmonary tuberculosis (PTB) is difficult to diagnose. Current diagnosis and treatment monitoring methods have inherent limitations. Droplet digital PCR (ddPCR) is a new technique with high sensitivity. This study presents a novel ddPCR for rapid and sensitive identification of Mycobacterium tuberculosis (MTB).

METHODS

MTB DNA was detected in respiratory specimens from suspected PTB cases using ddPCR assay, which was directed at two different locations within IS6110. We, for the first time, evaluated the clinical diagnostic ability of this ddPCR for paucibacillary smear-negative PTB.

RESULTS

A total of 605 PTB suspects were recruited, including 263 confirmed PTB patients (84.03% from smear-negative PTB) and 342 non-PTB. The sensitivity and specificity of IS6110 ddPCR were 61.22% (95% confidence interval (CI), 55.00%-67.10%) and 95.03% (95% CI, 92.20%-97.10%) for total PTB, and 57.92% (95% CI, 51.10%-64.50%) and 94.57% (95% CI, 91.20%-96.90%) for smear-negative PTB. ddPCR assay outperformed Xpert MTB/RIF (53.08% vs. 28.46%, p = 0.020) in smear-negative PTB detection. Furthermore, effective anti-tuberculosis treatment was linked to significantly lower IS6110 copies detected by ddPCR.

CONCLUSIONS

Herein, we developed and validated a highly sensitive and robust ddPCR assay for MTB quantification in respiratory specimens, which improve diagnosis and therapeutic effect evaluation of smear-negative PTB.

Treatment Outcomes of Tuberculosis at Asella Teaching Hospital, Ethiopia: Ten Years' Retrospective Aggregated Data

BACKGROUND

Directly Observed Treatment Short-course (DOTS) has been one of the major strategies to combat the epidemic of tuberculosis (TB) globally. This study aimed to evaluate TB treatment outcomes between September 2004 and July 2014 under the DOTS program at one of the largest public hospitals in Ethiopia.

METHODS

A retrospective data of TB patients registered at Asella Teaching Hospital between September 2004 and July 2014 were obtained from hospital registry. Treatment outcomes and types of TB cases were categorized according to the national TB control program guideline. Binomial and multinomial logistic regression models were used to analyze the association between treatment outcomes and potential predictor variables.

RESULTS

A total of 1,755 TB patients' records were included in the study. Of these, 945 (53.8%) were male, 480 (27.4%) smear-positive TB, 287 (16.4%) HIV positive, and 1,549 (88.3%) new cases. Among 480 smear-positive pulmonary TB cases, 377 (78.5%) patients were cured, 21 (4.40) completed the treatment, 35 (7.3%) transferred out, 19 (4.0%) died, 24 (5.0%) defaulted, and 4 (0.8%) failure. Overall, 398 (82.9%) smear-positive pulmonary TB patients were successfully treated. For smear-negative TB (n = 641) and extrapulmonary TB cases (n = 634), 1,036 (81.3%) completed the treatment and demonstrated favorable response. Taking all TB types into account, 1,434 (81.7%) were considered as successfully treated. In the multivariate binary logistic model, patients in older age group (AOR = 0.386, 95% CI: 0.250-0.596) and retreatment cases (AOR = 0.422, 95% CI: 0.226-0.790) were less likely to be successfully treated compared to younger and new cases, respectively. In multinomial logistic regression, age increment by 1 year increased the risk of death and default of TB patients by 0.05 (adjusted β = 0.05; 95% CI: 0.03, 0.06) and 0.02 (adjusted β = 0.02; 95% CI: 0.01, 0.04). The odds of TB patients who died during treatment were higher among HIV-infected TB patients (adjusted β = 2.65; 95% CI: 1.28, 5.50).

CONCLUSION

The treatment success rate of TB patients was low as compared to the national target. TB control needs to be strengthened for the enhancement of treatment outcome.

Induced sputum versus bronchial washings in the diagnosis of sputum negative pulmonary tuberculosis

Introduction:

Tuberculosis (TB) is one of the most important public health problems worldwide. Detecting patients with active pulmonary TB (PT) is an important component of TB control programs. However, at times in patients even with a compatible clinical picture, sputum smears do not reveal acid-fast bacilli (AFB) and smear-negative PT remains a common problem. This study compares the results of induced sputum (IS) and bronchial washings (BWs) in detecting sputum negative PT.

Materials and Methods:

A prospective study conducted from June 2014 to June 2015, comprising 120 patients fulfilling study criteria. Patients with respiratory symptoms and chest roentgenogram suspicious of PT with no previous history of antiTB treatment (ATT) and two spontaneous sputum smear samples negative for AFB were included in the study. Patients with active hemoptysis and sputum positive were excluded from the study. Sputum induction was done using 5–10 ml of 3% hypertonic saline through ultrasonic nebulizer taking safety precautions. All the patients underwent fiberoptic bronchoscopy after 6 h fasting on the same day. About 20 ml of normal saline instilled into the suspected pathology area and washings were taken with gentle suction. The sample processing and fluorescent staining for AFB were done in a designated microscopy laboratory.

Results:

Of 120 smear-negative PT patients, IS smear examination detected AFB in 76 patients (63.3%) and AFB detected from BWs in 94 patients (78.5%). Smear positivity higher in cavitary and infiltrative lesions compared to consolidation and infrahilar pattern disease.

Conclusions:

Even though both IS and BWs procedures were valuable for the diagnosis of smear-negative TB, sputum induction with hypertonic saline should be the initial procedure of choice, which can be repeated twice/thrice in a day or 2 consecutive days. If the patient remains IS smear-negative and if the clinical probability of TB is high, starting ATT and closely monitoring patient and reserving bronchoscopy to those patients who do not improve and to exclude alternative diagnosis seems to be a practically useful approach.

Diagnostic yield and safety of sputum induction with nebulized racemic salbutamol versus hypertonic saline in smear-negative pulmonary tuberculosis

OBJECTIVES

The aim of the study was to compare the diagnostic yield and safety profile of sputum induction (SI) with nebulized racemic salbutamol solution versus hypertonic saline in smear-negative pulmonary tuberculosis (TB).

METHODS

The prospective study was conducted at Songklanagarind Hospital, Thailand. Suspected smear-negative pulmonary TB cases were recruited and randomized to receive SI with either nebulized racemic salbutamol solution or 3% sodium chloride (NaCl) solution. Induced sputum was examined with the acid-fast bacilli (AFB) smear test and cultured for Mycobacterium tuberculosis. The efficacy and adverse events of SI were analyzed.

RESULTS

A total of 59 patients received SI with nebulized racemic salbutamol solution and 53 received 3% NaCl solution. There was no significant difference between the two groups in the average quantity of induced sputum (1.3 ± 0.1 versus 1.2 ± 0.2 ml, p = 0.5). The percentages of positive AFB smear and TB cultures in the salbutamol group were 15% and 22%, and 13% and 17% in the 3% NaCl group (p = 0.5), respectively. Racemic salbutamol solution could increase the TB diagnostic yield similarly to 3% NaCl, but incurred less chest tightness (5% versus 15%) and bronchospasm (0% versus 11.3%, p = 0.02) compared with 3% NaCl.

CONCLUSIONS

SI by nebulized racemic salbutamol solution offers equal benefits to 3% NaCl solution in increasing both sputum quantity and diagnostic yield in smear-negative patients suspected of having pulmonary TB. Nebulized racemic salbutamol does not produce bronchospasm and chest tightness occurs less frequently than with 3% NaCl. Therefore, SI with nebulized racemic salbutamol solution should be considered as a good alternative noninvasive diagnostic tool for the diagnosis of pulmonary TB when hypertonic saline is unavailable or contraindicated.

Diagnostic value of nucleic acid amplification tests on bronchoalveolar lavage fluid for smear-negative pulmonary tuberculosis: a meta-analysis

Based on current available evidence, NAAT on BALF plays a role in the diagnosis of smear-negative pulmonary tuberculosis, and further studies should be performed to confirm our findings..

The diagnosis of smear-negative pulmonary tuberculosis (SNPT) remains a clinical challenge. Many studies suggest that nucleic acid amplification tests (NAATs) on bronchoalveolar lavage fluid (BALF) plays a role in diagnosing SNPT, but with considerable varying results. The current study aimed to summarize the overall diagnostic accuracy of NAATs assay on BALF for SNPT. A systematic literature search was performed and data were retrieved. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) were calculated. A summary receiver operating characteristic curve and area under the curve (AUC) were used to evaluate the overall diagnostic performance. All the statistical analysis was performed by using STATA 12.0 and Meta-DiSc 1.4 software. A total of nine studies with 1214 subjects were included this meta-analysis. The pooled sensitivity, specificity, PLR, NLR and DOR were 0.54 [95% CI (confidence interval): 0.48–0.59], 0.97 (95% CI: 0.95–0.98), 12.13 (95% CI: 8.23–17.88), 0.36 (95% CI: 0.23–0.56) and 44.71 (95% CI: 22.30–89.63) respectively. The AUC was 0.96. Estimated positive and negative post-probability values for a SNPT prevalence of 20% were 82% and 7% respectively. No publication bias was identified. Current available evidence indicated that NAATs on BALF may play a role in diagnosing SNPT, whereas the results should be interpreted in parallel with clinical information of patients and the results of traditional tests. Further studies should be performed to confirm our findings.