The incremental value of bronchoalveolar lavage for the diagnosis of pulmonary tuberculosis in a high-burden urban setting

Diagnostic performance of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) in bronchoalveolar lavage fluid for pulmonary tuberculosis in HIV-infected patients

Introduction

Pulmonary tuberculosis (PTB) remains a significant health concern, particularly in individuals infected with human immunodeficiency virus (HIV) who are more susceptible to developing active TB disease. Early and accurate diagnosis of TB is crucial for effective treatment and prevention of transmission. This study aims to evaluate the potential of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis of bronchoalveolar lavage fluid (BALF) for diagnosis of suspected PTB in HIV-infected patients.

Methods

This retrospective study recruited 60 HIV-infected patients with suspected PTB presenting with respiratory symptoms and abnormal chest radiographs between January 2022 and June 2023. BALF samples were collected and subjected to analysis using MALDI-TOF MS, GeneXpert, acid-fast bacilli (AFB) smear and culture. And their diagnostic performance was compared.

Results

The sensitivity of MALDI⁃TOFMS for diagnosing PTB was 83.3 %, which was better than that of smear 11.9 %, culture 40.5 % or Xpert38.1 % (all p < 0.01). The area under the curve (AUC) value of MALDI⁃TOFMS was 0.889, which was better than that of smear 0.532, culture 0.675 or Xpert 0.690 (all p < 0.01). The katG315 and rpoB-RRDR 511 mutations were detected by the MALDI⁃TOFMS in two patients.

Conclusion

Nucleotide MALDI-TOFMS has a good clinical performance for rapid diagnosis of PTB from BALF samples in HIV infected patients, and detects mutations of TB simultaneously.

Detection of antigen Ag85B expression is useful for the diagnosis of tuberculosis, especially for those with an antituberculosis treatment history

OBJECTIVES

The present study used immunohistochemistry (IHC) to detect antigen Ag85B in tissue sections and aimed to evaluate its validity in histopathologic diagnosis of tuberculosis (TB).

METHODS

In total, 204 patients with confirmed TB and 40 other diseases were included in the present study. Ziehl-Neelsen (Z-N) stains, IHC (anti-Ag85B), and quantitative fluorescence polymerase chain reaction were used to detect acid-fast bacilli, Mycobacterium tuberculosis (MTB) antigen, and MTB DNA.

RESULTS

Immunohistochemistry was significantly more sensitive than Z-N stains (93.1% vs 67.2%; P < .001). The sensitivity of Z-N stains significantly correlated with anti-TB treatment history. The sensitivity of Z-N stains was lower in rifampicin (RIF)-resistant TB compared with RIF-sensitive TB (52.8% vs 69.0%; P = .091) and those without treatment history (52.8% vs 84.0%; P = .015). However, IHC was not significantly affected by treatment history (P = .410). Moreover, expression patterns of Ag85B were dependent on treatment history and commonly showed weak scattered spots in RIF-susceptible TB. Conversely, strong brown rods were often found in those with RIF-resistant TB.

CONCLUSIONS

Immunohistochemistry is a simple, sensitive technique for the diagnosis of TB, especially for those patients with treatment history. The expression pattern of Ag85B is a potential marker for evaluating anti-TB treatment response.

Prevalence and Risk Factors of Subclinical Tuberculosis in a Low-Incidence Setting in China

Objectives: Subclinical tuberculosis (TB) represents a substantial proportion of individuals with TB disease, although limited evidence is available to understand the epidemiological characteristics of these cases. We aimed to explore the prevalence of subclinical patients with TB and identify the underlying association between the subclinical TB cases in the study setting and the Beijing genotype.

Methods: A retrospective study was conducted among patients with incident TB at the Fifth People’s Hospital of Suzhou between January and December 2018. A total of 380 patients with TB were included in our analysis.

Results: Of the 380 patients, 81.8% were active TB cases, whereas the other 18.2% were subclinical TB cases. Compared with patients aged 65 years and older, the risk of having subclinical TB is higher among younger patients. The use of smear, culture, and Xpert identified 3, 16, and 13 subclinical TB cases, respectively. When using a combination of positive culture and Xpert results, the sensitivity improved to 33.3%. In addition, the neutrophil-to-lymphocyte ratio was significantly elevated in the active TB group compared with that in the subclinical TB group. We also observed that the proportion of the Beijing genotype in the subclinical TB group was significantly lower than that in the active TB group.

Conclusion: To conclude, our data demonstrate that approximately one-fifth of patients with TB were subclinical in Suzhou. Mycobacterium tuberculosis could be detected by the existing microbiologic diagnostics in one-third of patients with subclinical TB. The patients with subclinical TB are more prone to having low neutrophil-to-lymphocyte ratio values than those with active TB. Additionally, non-Beijing genotype strains are associated with subclinical TB.

Comparison of LAMP, GeneXpert, Mycobacterial Culture, Smear Microscopy, TSPOT.TB, TBAg/PHA Ratio for Diagnosis of Pulmonary Tuberculosis

Objective

To investigate the application value of loop-mediated isothermal amplification (LAMP), GeneXpert, mycobacterial culture, smear microscopy, TSPOT.TB (TSPOT), ratio of TB-specific antigen to phytohemagglutinin (TBAg/PHA ratio) in the detection of mycobacterium tuberculosis in the bronchoalveolar lavage fluid.

Methods

A retrospective analysis was performed on the patients who underwent bronchoscopy from December 2018 to November 2019 in Tongji Hospital. The patients with positive tuberculosis culture or positive GeneXpert in bronchoalveolar lavage fluid were selected as the case group, and those without tuberculosis served as the control group. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of LAMP, GeneXpert, culture, smear microscopy, TSPOT, and TBAg/PHA ratio.

Results

For the patients with positive cultures as case, the sensitivity of LAMP, GeneXpert, smear microscopy, TSPOT and TBAg/PHA ratio was 73.49%, 89.16%, 25.30%, 80.00%, 33.85%, respectively, the specificity was 99.00%, 100.00%, 99.00%, 86.00%, 100.00%, respectively, the area under the ROC curve (AUC) was 0.849, 0.938, 0.633, 0.830, 0.669, respectively. For the patients with positive GeneXpert as case, the sensitivity of LAMP, mycobacterial culture, smear microscopy, TSPOT and TBAg/PHA ratio was 73.20%, 74.23%, 22.68%, 68.92%, 29.73%, respectively, the specificity was 99.00%, 100.00%, 99.00%, 86.00%, 100.00%, respectively, the AUC was 0.853, 0.878, 0.623, 0.775, 0.649, respectively.

Conclusion

The sensitivity of GeneXpert was best. The sensitivity and diagnostic value of LAMP were slightly lower than those of GeneXpert, and were similar to tuberculosis culture. The sensitivity of smear microscopy was low. The specificity of TSPOT was low. When TBAg/PHA ratio >0.2 was used as a diagnostic index, the specificity was improved, but the sensitivity was low.

Dependence of Xpert MTB/RIF Accuracy for Detecting Rifampin Resistance in Bronchoalveolar Lavage Fluid on Bacterial Load: A Retrospective Study in Beijing, China

INTRODUCTION

We assessed the effect of Mycobacterium tuberculosis (MTB) bacterial load on Xpert MTB/RIF accuracy for detection of rifampicin (RIF)-resistant MTB in bronchoalveolar lavage fluid (BALF) specimens obtained at a national tuberculosis (TB) specialized hospital in Beijing, China.

METHODS

A retrospective study was conducted at Beijing Chest Hospital. Patients with symptoms suggestive of pulmonary TB who provided BALF specimens for routine MTB detection between June 2019 and July 2020 were enrolled in the study. Chi-square test and Student's t-test were used to compare results across groups stratified according to BALF bacterial load.

RESULTS

In total, 1125 patients with positive Xpert results who were enrolled in final analysis, 263 provided BALF specimens that tested positive for RIF-resistant MTB via Xpert MTB/RIF. The RIF-resistance rate of specimens with very low MTB bacterial load was 30.9%, a resistance rate significantly greater than rates obtained for groups with high (25.0%), medium (17.3%) and low (19.2%) MTB loads (P<0.01). Notably, false-positive results obtained for the very low bacterial load group led to markedly reduced positive predictive value of Xpert MTB/RIF to provide correct RIF-resistance predictions for that group (67.1%, 95% CI: 56.1%-78.1%5) relative to the predictive value obtained for all other groups combined (about 90%, P<0.05). Sanger sequencing data obtained for 20 (32.8%) MTB isolates deemed RIF-resistant via Xpert (Probe E) lacked rpoB RRDR mutations. Meanwhile, of another group of 23 isolates deemed RIF-susceptible via DST but RIF-resistant via Xpert MTB/RIF, 20 isolate sequences (87.0%) lacked rpoB RRDR mutations, while sequences of the remaining 3 isolates harbored single rpoB RRDR mutations predicted to cause amino acid substitutions.

CONCLUSION

Xpert MTB/RIF assay performed alarmingly poorly when used to detect RIF-resistant MTB in BALF specimens with very low bacterial loads. A high rate of Xpert probe E hybridization failure was the main driver of false-positive RIF-resistant results.

Value of Xpert MTB/RIF Using Bronchoalveolar Lavage Fluid for the Diagnosis of Pulmonary Tuberculosis: a Systematic Review and Meta-analysis

The performance of Xpert MTB/RIF using bronchoalveolar lavage fluid (BAL) for the diagnosis of pulmonary tuberculosis (PTB) remains unclear. Therefore, a systematic review/meta-analysis was conducted. Studies published before 31 December 2019 were retrieved from the PubMed, Embase, and Web of Science databases using the keywords "pulmonary tuberculosis," "Xpert MTB/RIF," and "BAL." Two independent evaluators extracted the data and assessed the bias risk of the included studies. A random-effects model was used to calculate the overall sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR, respectively), diagnostic odds ratio (DOR), and the area under the curve (AUC), as well as the respective 95% confidence intervals (CIs). Nineteen trials involving 3,019 participants met the inclusion criteria. Compared to the culture method, the pooled sensitivity, specificity, PLR, NLR, DOR, and the AUC with 95% CIs of Xpert MTB/RIF were 0.87 (0.84 to 0.90), 0.92 (0.91 to 0.93), 10.21 (5.78 to 18.02), 0.16 (0.12 to 0.22), 78.95 (38.59 to 161.53), and 0.9467 (0.9462 to 0.9472), respectively. Relative to the composite reference standard, the observed values were 0.69 (0.65 to 0.72), 0.98 (0.98 to 0.99), 37.50 (18.59 to 75.62), 0.30 (0.21 to 0.43), 171.98 (80.82 to 365.96), and 0.9691 (0.9683 to 0.9699), respectively. All subgroups, except children, showed high sensitivity and specificity. In conclusion, the use of Xpert MTB/RIF in the context of BAL samples has a high diagnostic performance for PTB (except for children) and may serve as an alternative rapid diagnostic tool.

Diagnostic Yield of Oral Swab Testing by TB-LAMP for Diagnosis of Pulmonary Tuberculosis

Objective

A prospective study was conducted to ascertain the accuracy of oral swab specimens collected in the early morning, spot and at night for detecting pulmonary tuberculosis (TB).

Methods

We prospectively enrolled patients with symptoms suggestive of pulmonary TB in Beijing Chest Hospital. An early morning sputum specimen was collected from each patient for GeneXpert MTB/RIF (Xpert) and mycobacterial culture. In addition, three oral swabs were collected for TB-LAMP testing.

Results

With the combined results of three oral swab specimens, the proportion of Mycobacterium tuberculosis (MTB)-positive cases achieved 40.6%, which was comparable to results for Xpert and MGIT (P=0.603). Using Xpert plus MGIT as reference, the sensitivity of OS-LAMP on a single specimen ranged from 32.6% on the night oral swab to 50.0% on the morning swab. The combination of three oral swab specimens correctly identified 38 MTB-positive cases, indicating an overall sensitivity of 82.6%, which was significantly higher than that of a single oral swab specimen (P<0.001, P=0.001).

Conclusion

Oral swab can be used as an alternative specimen for diagnosis of pulmonary TB using TB-LAMP. Morning oral swab exhibits the highest sensitivity, and the inclusion of more specimens at different time points provides compensation in diagnostic sensitivity with single oral swab.

Bronchial brushing Xpert improves the diagnostic efficiency of sputum Xpert in patients with pulmonary tuberculosis

BACKGROUND

The role of bronchial brushing Xpert MTB/RIF (hereafter referred to as Xpert) in patients with pulmonary tuberculosis (PTB) remains unclear. Therefore, a retrospective study was conducted aiming to evaluate the diagnostic efficiency of bronchial brushing Xpert in patients with PTB.

METHODS

Between July 2018 and August 2019, suspected PTB patients who were admitted to our hospital and had bronchial brushing and matched sputum collection for acid-fast bacilli (AFB) smear, mycobacterial culture, and Xpert were included for further analysis. Subsequently, PTB was defined based on mycobacterial culture, and if an alternative diagnosis was established, 'non-tuberculosis (TB)' was considered. Comparison of bronchial brushing and matched sputum examination was performed between groups. Then, the differences in the sensitivities between bronchial brushing and sputum Xpert were examined using the chi-square test.

RESULTS

A total of 111 patients were included and divided into TB and non-TB groups (52 versus 59 patients). The sensitivities of Xpert against culture were calculated as follows: sputum, 44.2% (23/52); bronchial brushing, 59.6% (31/52); sputum and bronchial brushing, 69.2% (36/52). The specificities of all Xpert assays were the same (100.0%, 59/59). A significant difference was found in the comparison of the sensitivities of Xpert using sputum, bronchial brushing and both, and the sensitivity of Xpert on both sputum and bronchial brushing was higher than that on sputum alone (p < 0.05). Moreover, it appears that bronchial brushing Xpert was more sensitive than sputum Xpert in the detection of PTB.

CONCLUSION

Bronchial brushing Xpert improves the diagnostic efficiency of sputum Xpert in the detection of PTB.

Comparison of the diagnostic efficacy of the CapitalBio Mycobacterium real-time polymerase chain reaction detection test and Xpert MTB/RIF in smear-negative pulmonary tuberculosis

To compare the diagnostic efficacy of CapitalBio Mycobacterium real-time polymerase chain reaction (RT-PCR) detection test and the first-generation Xpert MTB/RIF in smear-negative pulmonary tuberculosis (PTB). In this retrospective study of smear-negative PTB, we reviewed patient medical records to determine the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of Xpert MTB/RIF, CapitalBio Mycobacterium detection test, and the parallel test (positive result for either of the Xpert MTB/RIF and CapitalBio Mycobacterium detection tests) to evaluate their diagnostic accuracy against a composite reference standard. In total, 1553 patients were evaluated. The sensitivity, specificity, PPV, NPV, and AUC of Xpert MTB/RIF, CapitalBio Mycobacterium detection test, and the parallel test were 57.1%, 92.9%, 81.1%, 95.9%, and 0.75; 53.4%, 97.7%, 98.6%, 41.5%, and 0.76; and 66.2%, 90.8%, 95.5%, 47.7%, and 0.79, respectively. For the bronchoalveolar lavage fluid (BALF) specimens, these values for Xpert MTB/RIF, CapitalBio Mycobacterium detection test, and the parallel test were 68.8%, 97.7%, 99.2%, 43.9%, and 0.83; 61.7%, 97.7%, 99.1%, 38.9%, and 0.80; and 77.0%, 95.5%, 98.6%, 50.9%, and 0.86, respectively. CapitalBio Mycobacterium detection test had moderate accuracy for smear-negative PTB, similar to Xpert MTB/RIF. The parallel test improved the sensitivity. BALF significantly improved the sensitivity and diagnostic accuracy of the test. The maximum diagnostic accuracy for smear-negative PTB was obtained with the parallel test and BALF specimens. BALF was the most effective specimen for diagnosing smear-negative PTB.