Performance of Xpert® MTB/RIF in diagnosing tuberculous pleuritis using thoracoscopic pleural biopsy

Features which discriminate between tuberculosis and haematologic malignancy as the cause of pleural effusions with high adenosine deaminase

BACKGROUND

Adenosine deaminase (ADA) is a useful biomarker for the diagnosis of tuberculous pleurisy (TBP). However, pleural effusions with high ADA can also be caused by other diseases, particularly hematologic malignant pleural effusion (hMPE). This study aimed to investigate the features that could differentiate TBP and hMPE in patients with pleural effusion ADA ≥ 40 IU/L.

METHODS

This was a retrospective observational study of patients with pleural effusion ADA ≥ 40 IU/L, conducted at a Korean tertiary referral hospital with an intermediate tuberculosis burden between January 2010 and December 2017. Multivariable logistic regression analyses were performed to investigate the features associated with TBP and hMPE, respectively.

RESULTS

Among 1134 patients with ADA ≥ 40 IU/L, 375 (33.1%) and 85 (7.5%) were diagnosed with TBP and hMPE, respectively. TBP and hMPE accounted for 59% (257/433) and 6% (27/433) in patients with ADA between 70 and 150 IU/L, respectively. However, in patients with ADA ≥ 150 IU/L, they accounted for 7% (9/123) and 19% (23/123), respectively. When ADA between 40 and 70 IU/L was the reference category, ADA between 70 and 150 IU/L was independently associated with TBP (adjusted odds ratio [aOR], 3.11; 95% confidence interval [CI], 1.95-4.95; P < 0.001). ADA ≥ 150 IU/L was negatively associated with TBP (aOR, 0.35; 95% CI, 0.14-0.90; P = 0.029) and positively associated with hMPE (aOR, 13.21; 95% CI, 5.67-30.79; P < 0.001). In addition, TBP was independently associated with lymphocytes ≥ 35% and a lactate dehydrogenase (LD)/ADA ratio < 18 in pleural effusion. hMPE was independently associated with pleural polymorphonuclear neutrophils < 50%, thrombocytopenia, and higher serum LD. A combination of lymphocytes ≥ 35%, LD/ADA < 18, and ADA < 150 IU/L demonstrated a sensitivity of 0.824 and specificity of 0.937 for predicting TBP.

CONCLUSION

In patients with very high levels of pleural effusion ADA, hMPE should be considered. Several features in pleural effusion and serum may help to more effectively differentiate TBP from hMPE.

Current status and future landscape of diagnosing tuberculosis infection

Interferon-γ release assays (IGRAs), such as QuantiFERON-TB Gold (QFT) or T-SPOT.TB, are frequently used as tools for the diagnosis of tuberculosis (TB) infection in the 21st century. QFT-Plus recently emerged as the fourth generation of QFT assays and has replaced QFT In-Tube. However, IGRAs have several problems regarding the identification of active, latent, and cured TB infection, and the time-consuming diagnosis of TB infection because of the overnight incubation of clinical specimens or complexity of measuring the level of interferon (IFN)-γ. To easily diagnose TB infection and quickly compare it with conventional IGRAs, many in vitro tests are developed based on assays other than enzyme-linked immunosorbent assay or enzyme-linked immunospot, such as the fluorescent lateral flow assay that requires less manual operation and a shorter time. Simplified versions of IGRAs are emerging, including QIAreach QuantiFERON-TB. On the other hand, to distinguish active TB from latent or cured TB infection, new immunodiagnostic biomarkers beyond IFN-γ are evaluated using QFT supernatants. While IFN-γ or IFN-γ-related chemokine such as IFN-γ induced protein 10 is a potential biomarker in patients with active TB, interleukin-2 or latency-associated antigen such as heparin-binding hemagglutinin may be useful to distinguish active TB from latent or cured TB infection. There are no potential biomarkers to fully distinguish the time-phase of TB infection at present. It is necessary to discover new immunodiagnostic biomarkers to facilitate decisions on treatment selection for active or latent TB infection.

Diagnostic value of nucleic acid amplification tests for tuberculous pleural effusion

Diagnosing tuberculous pleural effusion (TPE) is challenging for pulmonologists and laboratory scientists. The gold standards for TPE diagnosis are pleural fluid Ziehl-Neelsen staining, Mycobacterium tuberculosis (Mtb) culture and pleural biopsy. These tools have limitations, including low sensitivity, long turnaround time and invasiveness. The nucleic acid amplification test (NAAT) is a rapid and minimally invasive tool for diagnosing TPE. This review summarizes the diagnostic accuracy of available NAATs for TPE, with a focus on the evidence from systematic reviews and meta-analyses. The NAATs summarized in this review include in-house NAATs, GeneXpert-MTB/RIF, GeneXpert-MTB/RIF Ultra, simultaneous amplification and testing-tuberculosis, FluoroType MTB and loop-mediated isothermal amplification.

Comparison of Performances of GeneXpert MTB/RIF, Bactec MGIT 960, and Bactec Myco/F Systems in Detecting Mycobacterium tuberculosis in Biopsy Tissues: a Retrospective Study

Tuberculosis remains a major global public concern as a leading cause of health care-associated infections. The detection of Mycobacterium tuberculosis (MTB) is challenging due to the paucibacillary nature of the pathogen. For suspected pulmonary and extrapulmonary tuberculosis patients, if sputum, bronchoalveolar lavage fluid (BALF), related samples are negative for MTB, or suspected tumors, biopsy tissues may provide a better diagnostic yield. This study was aimed at comparing the performances of three methods in identifying MTB in biopsy tissues, including the Bactec mycobacterial growth indicator tube 960 (MGIT 960) system, the GeneXpert MTB/RIF assay (GeneXpert), and the Bactec Myco/F lytic culture (Myco/F) system. Biopsy samples from 3,209 nonduplicated patients were retrospectively enrolled between January 2018 and September 2021, of which 180 (5.6%) were positive for MTB by at least one method. GeneXpert revealed the highest recovery rate (134/162, 82.7%), followed by MGIT 960 (99/135, 73.3%) and Myco/F (26/143, 18.1%), and the composite positive rate for GeneXpert and MGIT 960 was 96.6% (173/179). Pairwise comparisons were conducted after completion of both tests, and the results showed that Myco/F had significantly lower detection rates than GeneXpert and MGIT 960 (16.4% versus 82.8%, P < 0.001; 14.3% versus 71.4%, P < 0.001). In summary, GeneXpert was the most sensitive and recommended method for MTB detection in biopsy tissues, and the combination of GeneXpert and MGIT 960 could improve the overall diagnostic yield. IMPORTANCE Mycobacterium tuberculosis (MTB) poses a severe threat to public health worldwide. The diagnosis of tuberculosis is challenging due to the low load of the microorganism in samples. Biopsy tissues are sometimes collected via invasive procedures with limited size, and additional samples are often inaccessible. The GeneXpert MTB/RIF assay, Bactec MGIT 960 system, and Bactec Myco/F lytic system have been used in detecting MTB in our laboratory. Here, we evaluated the performances of these three methods in 3,209 biopsy tissues samples to establish a more effective protocol based on clinical requirements. Attempts for a locally optimized protocol should be always made.

Expert Review on Contemporary Management of Common Benign Pleural Effusions

Heart failure (HF) and cirrhosis are frequently associated with pleural effusions (PEs). Despite their apparently benign nature, both HF-related effusions and hepatic hydrothorax (HH) have poor prognosis because they represent an advanced stage of the disease. Optimization of medical therapy in these two entities involve not only the use of diuretics, but also other pharmacological therapies. For instance, all HF patients with reduced or mildly reduced left ventricular ejection fraction can benefit from angiotensin receptor-neprilysin inhibitors, beta blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors. Conversely, it is better for HH patients to avoid nonselective beta blockers. Refractory cardiac- and cirrhosis-related PEs are commonly managed by iterative therapeutic thoracentesis. When repeated aspirations are needed, thereby diminishing quality of life, the insertion of an indwelling pleural catheter (IPC) may be warranted. However, in selected HH patients who are diuretic-resistant or diuretic-intractable, placement of transjugular intrahepatic portosystemic shunts should be considered as a bridge to liver transplantation, whereas in transplant candidates the role of IPC is debatable. Another benign condition, pleural tuberculosis (TB) is a serious health problem in developing countries. Diagnostic certainty is still a concern due to the paucibacillary nature of the infection, although the use of more sensitive nucleic acid amplification tests is becoming more widespread. Its treatment is the same as that of pulmonary TB, but the potential drug interactions between antiretroviral and anti-TB drugs in HIV-coinfected patients as well as the current recommended guidelines for the different types of anti-TB drugs resistance should be followed.

Diagnosis of tuberculous pleural effusion in a tertiary care hospital of central India: The role of xpert Mycobacterium tuberculosis/rifampicin

Background

In India, 15%-20% of tuberculosis (TB) cases are categorized as extra-pulmonary TB, and tuberculous pleural effusion (TPE) is the second-most common type after tuberculous lymphadenitis. However, the paucibacillary nature of TPE makes its diagnosis challenging. As a result, relying on empirical anti-TB treatment (ATT) based on clinical diagnosis becomes necessary for achieving the best possible diagnostic outcome. The study aims to determine the diagnostic utility of Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) for the detection of TB in TPE in high incidence setting of Central India.

Methods

The study enrolled 321 patients who had exudative pleural effusion detected through radiological testing and were suspected of having TB. The medical procedure of thoracentesis was conducted to collect the pleural fluid, which was then subjected to both the Ziehl-Neelsen staining and Xpert MTB/RIF test. The patients who showed improvement after receiving anti-tuberculosis treatment (ATT) were considered the composite reference standard.

Results

The sensitivity of smear microscopy was found to be 10.19%, while that of the Xpert MTB/RIF method was 25.93% when compared to the composite reference standard. The accuracy of clinical diagnosis was measured using receiver operating characteristics based on clinical symptoms, and it was found to be 0.858 (area under the curve).

Conclusions

The study shows that Xpert MTB/RIF has significant value in diagnosing TPE, despite its low sensitivity of 25.93%. Clinical diagnosis based on symptoms was relatively accurate, but relying on symptoms alone is not enough. Using multiple diagnostic tools, including Xpert MTB/RIF, is crucial for accurate diagnosis. Xpert MTB/RIF has excellent specificity and can detect RIF resistance. Its quick results make it useful in situations where a rapid diagnosis is necessary. While it should not be the only diagnostic tool, it has a valuable role in diagnosing TPE.

Study of diagnostic utility of Xpert MTB/Rif test on pleural fluid in the evaluation of patients presenting with Pleural Tuberculosis in Nepal

Introduction

Existing tests for the diagnosis of pleural tuberculosis (TB) have major limitations in terms of accuracy, time to diagnosis and drug resistance testing. A test which can diagnose pleural TB and detect resistance, like Xpert MTB/Rif, would be optimal for rapid diagnosis and treatment.

Methods

A prospective observational study was done in a tertiary care hospital in Eastern Nepal. Fifty-one patients with clinic-radiologic suspicion of pleural TB were included. The results of pleural fluid Xpert MTB/Rif were compared with two Composite Reference Standards. Composite Reference Standard-1 consisted of positive pleural fluid smear, positive culture, positive histology of pleural biopsy, and positive sputum results. Composite Reference Standard-2 included those with Composite Reference Standard-1 and those with high ADA values (>40 U/l) with response to anti-tubercular treatment at 8 weeks of follow-up.

Results

Thirty-six patients were diagnosed as Pleural TB. Nine fulfilled Composite Reference Standard-1. Pleural fluid Xpert MTB/Rif was positive in five cases with Composite Reference Standard-1 and nine cases with Composite Reference Standard-2. The sensitivity, specificity, positive predictive value and negative predictive value with reference to Composite Reference Standard-1 were 55.56%, 88.10%, 50%, and 90.24%, respectively. Using Composite Reference Standard-2 as reference, sensitivity, specificity, positive predictive value and negative predictive value were 25%, 93.33%, 90%, and 34.15%, respectively. Two cases were diagnosed Xpert Rif resistant on pleural fluid.

Conclusion

Due to low sensitivity, the Xpert MTB/Rif test cannot be recommended as initial test of diagnosis in a high prevalence setting. At the same time its clinical utility lies in testing of patients suspected to have drug-resistant pleural tuberculosis.

Performance of TB-LAMP in the Diagnosis of Tuberculous Empyema Using Samples Obtained From Pleural Decortication

Purpose

To evaluate the performance of TB-LAMP in the diagnosis of TB empyema using pleural tissue specimens obtained during pleural decortication.

Methods

Using the clinical records and the different diagnostic test results of patients who underwent pleural decortication in a TB-designated hospital over 3.5 years, we calculated the sensitivity, specificity positive predictive, and negative predictive values of the pathology, MGIT 960 culture, and TB-LAMP obtained by using pleural tissue specimens against the etiologic diagnosis and composite clinical reference standard (CCRS) as the reference standards.

Result

A total of 304 patients' records were extracted. All these patients had gone through pleural decortication. When the etiologic diagnosis was used as the reference, the sensitivity of TB-LAMP in identifying TB empyema was 77.8% (compared to 10.6% of MGIT 960 P < 0.05). The sensitivity of MGIT 960, pathology, and TB-LAMP was 8.2%, 77.7%, and 67.2% against CCRS as the reference; and the specificity of the three was 100.0, 100.0, and 96.2% against the same standard. A combination of pathology and TB-LAMP would increase the sensitivity and specificity to 84.7 and 96.0%. Using TB-LAMP to diagnose TB empyema using pleural tissue samples obtained from pleural decortication was faster with satisfactory performance.

Conclusion

TB-LAMP has great potential in faster and more accurate diagnosis of TB empyema. Our findings provide insights for optimizing diagnostic algorithms for TB empyema.

The diagnostic value of T cell spot test and adenosine deaminase in pleural effusion for tuberculous pleurisy: A systematic review and meta-analysis

BACKGROUND

Tuberculous infection of T cell spot test (T-SPOT.TB) and adenosine deaminase (ADA) have a high diagnostic value in pleural effusion for tuberculous pleurisy. However, there were major differences in existing research in regard to the clinical application of the two trials. Therefore, we conducted a meta-analysis to systematically evaluate the diagnostic value of T-SPOT.TB and ADA.

METHODS

Pubmed, Web of Science and Embase databases were searched to compare diagnosis of tuberculous pleurisy by T-SPOT.TB and ADA. The search period was from inception to August 31, 2021. Statistical analyses were performed using Meta-disc 1.4, Revman 5.4 and Stata 16.0. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were determined. Summary receiver operating characteristic (SROC) curves and the area under the curve (AUC) were used to summarize overall diagnostic performance.

RESULTS

10 qualified original research studies were included, with a total of 2075 patients, of which were 1391 tuberculous pleurisy and 684 non-tuberculous pleurisy. The pooled estimates of diagnostic accuracy of T-SPOT.TB were as follows: sensitivity, 0.88 (95% CI: 0.86-0.90; I² = 92.7%); specificity, 0.79 (95% CI: 0.76-0.82; I² = 93.7%); PLR, 4.49 (95% CI: 2.29-8.80; I² = 94.9%); NLR, 0.15 (95% CI: 0.08-0.30; I² = 94.3%), DOR, 35.72 (95% CI: 11.15-114.47; I² = 91.5%). The AUC for SROC was 0.9283 (95% CI: 0.8912-0.9654). The pooled estimates of diagnostic accuracy of ADA were as follows: sensitivity, 0.65 (95% CI: 0.62-0.67; I² = 98.2%); specificity, 0.90 (95% CI: 0.88-0.92; I² = 69.4%); PLR, 6.12 (95% CI: 4.71-7.96; I² = 11.9%); NLR, 0.33 (95% CI: 0.12-0.89; I² = 99.5%), DOR, 23.18 (95% CI: 12.75-42.14; I² = 66.7%). The AUC for SROC was 0.9208 (95% CI: 0.9029-0.9387).

CONCLUSION

Both T-SPOT.TB and ADA had high value in the diagnosis of tuberculous pleurisy. The sensitivity of T-SPOT.TB was higher than ADA, but the specificity of ADA was higher than T-SPOT.TB. On the whole, T-SPOT. TB had similar diagnostic accuracy to ADA.

Diagnostic accuracy of adenosine deaminase for pleural tuberculosis in a low prevalence setting: A machine learning approach within a 7-year prospective multi-center study

OBJECTIVE

To analyze the performance of adenosine deaminase in pleural fluid combined with other parameters routinely measured in clinical practice and assisted by machine learning algorithms for the diagnosis of pleural tuberculosis in a low prevalence setting, and secondly, to identify effusions that are non-tuberculous and most likely malignant.

PATIENTS AND METHODS

We prospectively analyzed 230 consecutive patients diagnosed with lymphocytic exudative pleural effusion from March 2013 to June 2020. Diagnosis according to the composite reference standard was achieved in all cases. Pre-test probability of pleural tuberculosis was 3.8% throughout the study period. Parameters included were: levels of adenosine deaminase, pH, glucose, proteins, and lactate dehydrogenase, red and white cell counts and lymphocyte percentage in pleural fluid, as well as age. We tested six different machine learning-based classifiers to categorize the patients. Two different classifications were performed: a) tuberculous/non-tuberculous and b) tuberculous/malignant/other.

RESULTS

Out of a total of 230 patients with pleural effusion included in the study, 124 were diagnosed with malignant effusion and 44 with pleural tuberculosis, while 62 were given other diagnoses. In the tuberculous/non-tuberculous classification, and taking into account the validation predictions, the support vector machine yielded the best result: an AUC of 0.98, accuracy of 97%, sensitivity of 91%, and specificity of 98%, whilst in the tuberculous/malignant/other classification, this type of classifier yielded an overall accuracy of 80%. With this three-class classifier, the same sensitivity and specificity was achieved in the tuberculous/other classification, but it also allowed the correct classification of 90% of malignant cases.

CONCLUSION

The level of adenosine deaminase in pleural fluid together with cell count, other routine biochemical parameters and age, combined with a machine-learning approach, is suitable for the diagnosis of pleural tuberculosis in a low prevalence scenario. Secondly, non-tuberculous effusions that are suspected to be malignant may also be identified with adequate accuracy.