Challenges in pleural tuberculosis diagnosis: existing reference standards and nucleic acid tests

Pleural tuberculosis in Bhubaneswar, Odisha, during 2016 to 2022

We conducted a retrospective study to evaluate the burden of tuberculosis and rifampicin resistance in patients with pleural effusion in Bhubaneswar, Odisha, during February 2016, to December 2022, using cartridge-based nucleic acid amplification test (CBNAAT, Xpert MTB/RIF). Of the 1370 pleural fluid samples tested at the National Reference Laboratory for tuberculosis, 3.8% (52/1370) were positive for M.tuberculosis. Rifampicin resistance was detected in 3.8% (2/52) samples. The positivity was 5% in 2016, increased to 7.5% in 2020, and was 4.4% in 2022. The positivity varied across age groups, ranging from 1.5% in patients aged >60 years to 6.1% in 15-30 years.

Pleural Pustule-a Novel Thoracoscopic Appearance of Pleural Tuberculosis

BACKGROUND

Thoracoscopic pleural biopsy is the gold standard for diagnosing tubercular pleural effusion (TPE). Various thoracoscopic appearances like sago grain nodules, caseous necrosis, and adhesions have been described in TPE. However, none of these have high specificity for diagnosing TPE. In this study we evaluate a novel finding on thoracoscopy, the " Pleural Pustule."

METHODS

This is a retrospective analysis of patients who underwent thoracoscopy for undiagnosed pleural effusion. Visual inspection of the pleura was performed to identify abnormalities. Biopsies were obtained from those areas and sent for histopathology, acid fast bacillus (AFB) smear, culture, and Xpert MTB/Rif assay. Pleural pustule was defined as a pus filled nodule on the pleural surface.

RESULTS

Of the 259 patients included, 92 were diagnosed with TPE. Pleural pustule(s) were identified in 16 patients with TPE. Presence of pleural pustule had a sensitivity, specificity, positive predictive value, and negative predictive value of 17.4%, 100%, 100% and 68.7%, respectively, for diagnosing TPE. Histopathology of pleural pustule demonstrated necrotizing granulomas in all. In patients with pleural pustule, a microbiological diagnosis of tuberculosis was achieved in 93.7% patients (AFB smear, Xpert MTB/Rif assay, and MTB culture positive in 31.3%, 93.7%, and 43.7% cases, respectively). There is a strong association between pleural pustule and positive Xpert MTB/Rif assay ( P =0.002) and microbiologic confirmation of diagnosis ( P =0.017).

CONCLUSION

The presence of pleural pustule on thoracoscopy has a high positive predictive value for TPE. In tuberculosis-endemic countries, this can be considered suggestive for TPE. When identified, a biopsy from the pleural pustule should be performed as it will likely yield a positive microbiologic diagnosis.

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.

Developing a method to detect lipoarabinomannan in pleural fluid and assessing its diagnostic efficacy for tuberculous pleural effusion

Objectives

The diagnosis of tuberculosis pleural effusion (TPE) remains challenging, traditional diagnostic tests have limited diagnostic efficacy. This study aimed to assess the diagnostic performance of pleural fluid (PF) lipoarabinomannan (LAM) in TPE.

Methods

A diagnostic method for PF LAM (LAM-PF) was established using LEDBIO's AIMLAM kit. The diagnostic performance of LAM-PF was evaluated in 162 HIV-negative patients with suspected TPE.

Results

The LAM-PF method established in this study exhibited good linearity and recovery rate, with a limit of detection (LOD) of 2.90 pg/mL. Using a cut-off value of 5.33 pg/mL, the sensitivity and specificity of LAM-PF in diagnosing TPE (n = 128) were 47.7% and 100.0%, respectively. The sensitivity in patients with probable TPE (n = 29) and definite TPE (n = 99) were 41.4% and 49.5%, respectively. LAM-PF displayed a significantly higher sensitivity in probable TPE compared to other tuberculosis detection methods. Combined testing of adenosine deaminase (ADA)and LAM increased the detection sensitivity of TPE to 68.0%, and the area under the curve was 0.84 (0.77-0.89).

Conclusion

This study successfully established a method for detecting LAM in PF, which exhibited favorable diagnostic performance for TPE, particularly in challenging cases of probable TPE. Combined detection of LAM and ADA in PF significantly improves TPE diagnostic efficiency.

Diagnosis of pleural tuberculosis by multi-targeted loop-mediated isothermal amplification assay based on SYBR Green I reaction: comparison with GeneXpert® MTB/RIF assay

BACKGROUND

Diagnosis of pleural tuberculosis (TB) is tedious owing to its close resemblance with malignant pleural effusion and sparse bacterial load in clinical specimens. There is an immediate need to design a rapid and dependable diagnostic test to prevent unnecessary morbidity/mortality.

RESEARCH DESIGN AND METHODS

A multi-targeted loop-mediated isothermal amplification (MT-LAMP) was deliberated using mpt64 and IS6110 to diagnose pleural TB within pleural fluids/biopsies. MT-LAMP products were analyzed by gel-based and visual detection methods, viz. SYBR Green I, SYBR Green I+deoxyuridine triphosphate uracil-N-glycosylase (dUTP-UNG), and dry methyl green reactions.

RESULTS

In a pilot study, while assessing pleural TB/non-TB control subjects (n = 40), both SYBR Green I+dUTP-UNG/gel-based MT-LAMP assays exhibited better sensitivity/specificity than SYBR Green I and dry methyl green MT-LAMP. Since it is facile to work with SYBR Green I+dUTP-UNG than gel-based MT-LAMP, we validated the performance of SYBR Green I+dUTP-UNG in a higher number of specimens (n = 97), which revealed somewhat higher sensitivity (85.2 vs. 81.5%) and specificity (97.7 vs. 90.7%) than SYBR Green I MT-LAMP. Furthermore, the sensitivity attained by SYBR Green I+dUTP-UNG MT-LAMP was significantly higher (p < 0.001) than GeneXpert.

CONCLUSIONS

Our SYBR Green I+dUTP-UNG MT-LAMP is a simple and reliable method to diagnose pleural TB, which may translate into a point-of-care test.

A comparative study of ultrasound-guided puncture biopsy combined with histopathology and Xpert MTB/RIF in the diagnosis of lymph node tuberculosis

Background

Cervical tuberculous lymphadenitis (CTBL) is a disease often ignored in clinical work, and pathology and Xpert MTB/RIF (Xpert) are the commonly used methods for tuberculosis diagnosis. This study aimed to compare ultrasound-guided puncture biopsy combined with histopathology and Xpert in the diagnosis of lymph node tuberculosis.

Methods

A total of 217 patients highly suspected for CTBL were retrospectively enrolled. All patients underwent ultrasound-guided puncture sampling. All samples were subjected to pathological examination and Xpert test. The sensitivity and specificity of the two methods were compared for all samples. The kappa value was calculated to assess the consistency of the pathological examination and Xpert test using comprehensive diagnosis as the gold standard. Receiver operating characteristic curves of the pathological examination, Xpert test, and their combination were generated, and the areas under the curve (AUCs) were calculated to compare the diagnostic value of the three methods.

Results

The sensitivity and specificity of the pathological diagnosis of CTBL were 70.1 and 100%, respectively. The sensitivity and specificity of Xpert for CTBL diagnosis were 82.5 and 97.5%, respectively. The results of the pathological examination and Xpert test showed poor consistency in the diagnosis of CTBL, with a kappa value of 0.388. The AUC of the pathological diagnosis of CTBL was 0.850 (95% CI: 0.796-0.895), whereas that of Xpert was 0.900 (95% CI: 0.852-0.936), and the difference was statistically significant (P = 0.0483). The AUC of pathological examination combined with Xpert for the diagnosis of CTBL was 0.956 (95% CI: 0.920-0.979), and the difference between pathological examination combined with Xpert for the diagnosis of CTBL was statistically significant compared with pathological examination and Xpert alone, respectively (both P < 0.001).

Conclusion

The diagnostic efficiency of Xpert test is higher than that of pathological examination, but its sensitivity is still not ideal for clinical diagnosis. According to this study, the consistency of Xpert test and pathological diagnosis is poor, and the combination of Xpert test and pathological diagnosis can significantly increase the diagnostic efficiency.

An evaluation of Composite Reference Standard (CRS) for diagnosis of Female Genital Tuberculosis

BACKGROUND

Female genital tuberculosis (FGTB) is a common cause of infertility in developing countries. Its diagnosis is difficult due to its paucibacillary nature, with no single test having high sensitivity and specificity. This study is to share the experience of using Composite Reference Standard (CRS) for the diagnosis of FGTB.

METHODS

This is a prospective study conducted between September 2017 to June 2019, over 100 infertile females found to have FGTB on composite reference standard which consisted of acid-fast bacilli on microscopy or culture, histopathological evidence of epithelioid granuloma, positive gene Xpert on endometrial sample or definite or probable finding of FGTB on laparoscopy.

RESULTS

A total of 100 infertile women (78% primary, 22% secondary) found to have FGTB on CRS were enrolled in this study. Mean age, body mass index, parity and duration of infertility were 28.2 years, 23.17 kg/m², 0.24 ± 0.12 and 2.41 years respectively. Various symptoms were scanty menses (16%), irregular cycle (7%), dysmenorrhea (11%), pelvic pain (11%). Various signs were vaginal discharge (65%), adnexal mass (6%), tubo-ovarian mass on ultrasound (15%), abnormal hysterosalpingography findings (57.14%), positive polymerase chain reaction test (65%) and abnormal hysteroscopy (82.2%). The positive findings on CRS were positive AFB on microscopy or culture (3%), positive gene Xpert (28%) (done in some cases), epithelioid granuloma on histopathology (13%), definite findings on laparoscopy like tubercles, caseous nodules and beaded tubes in (57.19%) patients while probable findings of FGTB like straw colored fluid in POD, extensive dense pelvic, peri-tubal, peri-ovarian adhesions; hydrosalpinx; tubo-ovarian mass; thick fibrosed tubes; mid tubal block; peri hepatic adhesions (Fitz Hugh Curtis Syndrome); hyperemia of tubes/blue uterus on chromotubation were seen in (48.8%) patients. All patients found to be positive on CRS were given 6 months of anti-tubercular therapy.

CONCLUSION

This study demonstrates the high reliability of use of composite reference standard for diagnosis of FGTB.

Pleural fluid biochemical analysis: the past, present and future

Identifying the cause of pleural effusion is challenging for pulmonologists. Imaging, biopsy, microbiology and biochemical analyses are routinely used for diagnosing pleural effusion. Among these diagnostic tools, biochemical analyses are promising because they have the advantages of low cost, minimal invasiveness, observer independence and short turn-around time. Here, we reviewed the past, present and future of pleural fluid biochemical analysis. We reviewed the history of Light’s criteria and its modifications and the current status of biomarkers for heart failure, malignant pleural effusion, tuberculosis pleural effusion and parapneumonic pleural effusion. In addition, we anticipate the future of pleural fluid biochemical analysis, including the utility of machine learning, molecular diagnosis and high-throughput technologies. Clinical Chemistry and Laboratory Medicine (CCLM) should address the topic of pleural fluid biochemical analysis in the future to promote specific knowledge in the laboratory professional community.

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.

Insight into diagnosis of pleural tuberculosis with special focus on nucleic acid amplification tests

INTRODUCTION

Pleural tuberculosis (TB) is the archetype of extrapulmonary TB (EPTB), which mainly affects the pleural space and leads to exudative pleural effusion. Diagnosis of pleural TB is a difficult task predominantly due to atypical clinical presentations and sparse bacillary load in clinical specimens.

AREA COVERED

We reviewed the current literature on the globally existing conventional/latest modalities for diagnosing pleural TB. Bacteriological examination (smear/culture), tuberculin skin testing/interferon-γ release assays, biochemical testing, imaging and histopathological/cytological examination are the main modalities. Moreover, nucleic acid amplification tests (NAATs), i.e. loop-mediated isothermal amplification, PCR/multiplex-PCR, nested-PCR, real-time PCR and GeneXpert® MTB/RIF are being utilized. Currently, GeneXpert Ultra, Truenat MTB^TM, detection of circulating Mycobacterium tuberculosis (Mtb) cell-free DNA by NAATs, aptamer-linked immobilized sorbent assay and immuno-PCR (I-PCR) have also been exploited.

EXPERT OPINION

Routine tests are not adequate for effective pleural TB diagnosis. The latest molecular/immunological tests as discussed above, and the other tools, i.e. real-time I-PCR/nanoparticle-based I-PCR and identification of Mtb biomarkers within urinary/serum extracellular vesicles being utilized for pulmonary TB and other EPTB types may also be exploited to diagnose pleural TB. Reliable diagnosis and early therapy would reduce the serious complications associated with pleural TB, i.e. TB empyema, pleural fibrosis, etc.

Diagnosis of tuberculous pleural effusions: A review

Tuberculous pleural effusion (TPE) is the second most common presentation of extrapulmonary tuberculosis. The paucibacillary nature of the effusion poses diagnostic challenges. Biomarkers like adenosine deaminase and interferon-γ have some utility for diagnosing TPEs, as do cartridge-based polymerase chain reaction (PCR) methods. When these fluid studies remain indeterminate, pleural biopsies must be performed to confirm the diagnosis. This review article elaborates on the scientific evidence available for various diagnostic tests and presents a practical approach to the diagnosis of TPEs.

Diagnostic Procedures, Diagnoses, and Treatment Outcomes of Patients with Presumptive Tuberculosis Pleural Effusion in Uzbekistan

Tuberculosis (TB) pleural effusion (TPE) is the second most common manifestation of extrapulmonary TB (EPTB), which remains a great diagnostic challenge worldwide. In Uzbekistan, there has been no formal evaluation of the actual practices of diagnosing and treating TPE. Our cohort study therefore aimed to describe the frequency and types of different diagnostic procedures of TPE during 2017–2018 and assess the association of baseline characteristics and establish diagnostic methods with TB treatment outcomes. In total, 187 patients with presumptive TPE were assessed, and 149 had a confirmed diagnosis of TPE (other diagnoses included cancer n = 8, pneumonia n = 17, and 13 cases were unspecified). TB was bacteriologically confirmed in 22 (14.8%), cytologically confirmed in 64 (43.0%), and histologically confirmed in 16 (10.7%) patients. Hepatitis was the only co-morbidity significantly associated with unsuccessful treatment outcomes (RR 4.8; 95%CI: 1.44–15.98, p value 0.011). Multivariable regression analysis showed that drug-resistant TB was independently associated with unsuccessful TB treatment outcome. (RR 3.83; 95%CI: 1.05–14.02, p value 0.04). Multidisciplinary approaches are required to maximize the diagnostic accuracy of TPE and minimize the chances of misdiagnosis. TPE patients with co-infections and those with drug resistance should be more closely monitored to try and ensure successful TB treatment outcomes.

Performance of Xpert MTB/RIF Ultra for diagnosis of pulmonary and extra-pulmonary tuberculosis, one year of use in a multi-centric hospital laboratory in Brussels, Belgium

Among the challenges in controlling tuberculosis, a rapid and accurate diagnostic test for the detection of Mycobacterium tuberculosis complex (MTBc) and its resistance to first line therapies is crucial. We evaluated the performance of the Xpert MTB/RIF Ultra assay (Xpert Ultra) for the rapid detection of MTBc and rifampicin resistance (RR) in 1120 pulmonary and 461 extra-pulmonary clinical specimens and compared it with conventional phenotypic techniques. The Xpert Ultra assay detected MTBc in 223 (14.1%) samples with an overall sensitivity and specificity, using culture as the "gold standard", of 91.1% (95% CI, 85.6-95.1) and 94.5% (95% CI, 93.1-95.6), respectively. The sensitivity of the Xpert Ultra test for smear-negative extra-pulmonary specimens was high (87.1%), even higher than with smear-negative pulmonary specimens (81.8%). But this enhanced sensitivity came with a low overall specificity of smear-negative extra-pulmonary specimens (66.7%). For 73 patients, 79/1423 (3.4%) negative mycobacterial culture samples were found to be positive with Xpert Ultra. Clinical data was necessary to correctly interpret potential false-positive results, especially trace-positive results. Sensitivity of the Xpert Ultra to detect RR compared to drug susceptibility testing was 100% (95% CI, 29.2-100) and specificity was 99.2% (95% CI, 95.8-100). We concluded that the Xpert Ultra test is able to provide a reliable TB diagnosis within a significantly shorter turnaround time than culture. This is especially true for paucibacillary samples such as smear-negative pulmonary specimens and extra-pulmonary specimens.

Diagnostic Accuracy of Pleural Effusion Mononuclear Cells/Leukocyte Ratio in Tuberculous Pleurisy

Background: Tuberculous pleurisy (TBP) is a common clinical type of tuberculosis (TB) in China. TBP is difficult to diagnose. Whether the mononuclear cell/leukocyte (MNC/LEU) ratio in pleural effusion can contribute to accurate TBP diagnosis remains yet unclear.

Objective: To explore the diagnostic value of MNC/LEU ratio in pleural effusion for TBP in China.

Methods: This study was a retrospective case-control study involving 406 patients with pleural effusion of unknown cause who were hospitalized at the Henan Provincial People's Hospital. Using histopathological examination of thoracoscopic pleural biopsy as the gold standard for TBP diagnosis, a final total of 215 subjects were included in this study including 91 cases of TBP and 124 cases of non-TBP. The receiver operating characteristic (ROC) curve of pleural effusion MNC/LEU ratio for TBP diagnosis was plotted and the area under curve (AUC) and the optimal cutoff value were determined. In addition, the sensitivity, specificity and accuracy of the MNC/LEU ratio at the optimal cutoff value for TBP diagnosis were also evaluated.

Results: The MNC/LEU ratio was significantly higher in TB pleural effusion [95.9% (89.7–98.0%)] than in non-TB pleural effusion [77.8% (39.3–93.2%)] (P < 0.001). The AUC was 0.776 (95% CI, 0.714–0.830), and the sensitivity, specificity and accuracy for TBP diagnosis at the 93.7% cutoff value were 64.83%, 79.03%, and 0.730, respectively.

Conclusion: The pleural effusion MNC/LEU ratio may be a new and valuable laboratory indicator for the diagnosis of tuberculous pleurisy in China.

Performance Comparison of GeneXpert MTB/RIF and ProbeTec ET Tests for Rapid Molecular Diagnosis of Extrapulmonary Tuberculosis in a Low TB/MDR-TB Incidence Country

OBJECTIVE

This study evaluated the performance of GeneXpert MTB/RIF (Xpert) and ProbeTec ET (PTec-ET) assays in diagnosing extrapulmonary tuberculosis (EPTB) in Kuwait.

MATERIALS AND METHODS

We tested nonrespiratory clinical specimens (n = 3,995) collected from 3,995 patients suspected to have EPTB. These included cavitary fluids (n = 2,054), fine-needle aspirate (FNA)/pus/tissue biopsy (n = 1,461), urine (n = 302), cerebrospinal fluid (CSF, n = 118), and others (n = 60). All specimens were processed for acid-fast bacilli (AFB), culture in mycobacteria growth indicator tube 960 system, and nucleic acid detection by Xpert and PTec-ET according to manufacturer's instructions.

RESULTS

Of 3,995 specimens, 95 were AFB-positive, 403 were culture-positive, and an additional 86 samples had histopathology suggestive of TB. Using culture as reference, the sensitivity and specificity values were 88.33 and 97.3% for Xpert and 72.95 and 97.80% for PTec-ET, respectively. Although performance of both tests was comparable in AFB-positive samples, Xpert detected significantly more cases in culture-positive samples. Among culture-negative samples, Xpert detected 18 more cases including 16 with histopathological evidence of TB. Lowest positivity was detected for both tests in cavitary fluids. Xpert performed better than PTec-ET in culture-positive FNA/pus/tissue biopsy and CSF samples.

CONCLUSIONS

Although performance of both tests was suboptimal for AFB-negative/culture-positive samples, Xpert performed better than PTec-ET and also detected more cases of AFB-negative/culture-negative/histopathology-positive samples. PTec-ET was positive in 3, while Xpert was positive in all 6 culture-positive CSF specimens for rapid diagnosis of TB meningitis. Xpert was thus superior to PTec-ET or smear microscopy in rapid diagnosis of EPTB.

Metagenomic next generation sequencing for the diagnosis of tuberculosis meningitis: A systematic review and meta-analysis

Background

Tuberculous meningitis (TBM) is a severe form of extrapulmonary tuberculosis and its early diagnosis is very difficult leading to present with severe disability or die. The current study aimed to assess the accuracy of metagenomic next generation sequencing (mNGS) for TBM, and to identify a new test for the early diagnosis of TBM.

Methods

We searched for articles published in Embase, PubMed, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Data up to June 30, 2020 for studies that assessed the efficacy of mNGS for the diagnosis of TBM. Then, the accuracy between mNGS and a composite reference standard (CRS) in these articles was compared using the meta-analysis approach.

Results

Four independent studies with 342 samples comparing mNGS and a CRS were included in this study. The sensitivity of mNGS for TBM diagnosis ranged from 27% to 84%. The combined sensitivity of mNGS was 61%, and the I² value was 92%. Moreover, the specificity of mNGS for TBM diagnosis ranged from 96% to 100%. The combined specificity of mNGS was 98%, and the I² value was 74%. The heterogeneity between studies in terms of sensitivity and specificity was significant. The area under the curve (AUC) of the summary receiver operating characteristic curve (SROC) of mNGS for TBM was 0.98.

Conclusions

The sensitivity of mNGS for TBM diagnosis was moderate. Furthermore, the specificity was extremely high, and the AUC of the SROC indicated a very good diagnostic efficacy. mNGS could be used as an early diagnostic method for TBM, however, the results should be treated with caution for the heterogeneity between studies was extremely significant.

Systematic review registration

INPLASY202070100.

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

BACKGROUND

Etiological diagnosis of tuberculous pleuritis is challenging, owing to a paucity of Mycobacterium tuberculosis (MTB) in the affected region. Moreover, currently available methods, such as the detection of acid-fast bacilli and microbiological culture, are not always conducive to timely diagnosis and treatment. In this study, we evaluated the performance of Xpert® MTB/RIF assay (hereinafter referred to as "Xpert") in detecting MTB in difficult-to-diagnose patients using suspensions of pleural biopsy tissue specimens obtained under direct thoracoscopic guidance.

METHODS

One hundred and sixty patients with an unexplained pleural effusion were included from the Shenyang Tenth People's Hospital and Shenyang Chest Hospital, China, between 2017 and 2018. The included patients underwent thoracoscopy under local anesthesia, with an intercostal incision of approximately 1.0 cm for biopsy. The biopsy specimens were used for pathological and etiological examinations. The Xpert test was evaluated for its sensitivity and specificity, as well as positive and negative predictive values (PPV and NPV, respectively), against data obtained using standards: the BACTEC™ MGIT™ 960 liquid culture system and a composite reference standard (CRS).

RESULTS

The sensitivity and specificity of Xpert were 68.8 and 64.6%, respectively, against the MGIT 960 culture data. The PPV and NPV of Xpert were 56.4 and 75.6%, respectively. The sensitivity of Xpert was 69.0% against the CRS data, which was significantly higher than that of MGIT 960 culture (56.6%). The PPV and NPV of Xpert against the CRS data were 100.0 and 57.3%, respectively.

CONCLUSIONS

Xpert is a good rule-in test but has limited value as a rule-out test for the diagnosis of tuberculosis pleuritis.

Pleural Tuberculosis: A Febrile Presentation Without Respiratory Symptoms

Tuberculosis (TB) is one of the largest public health crises globally, with pleural TB comprising a large portion of cases. It has a significantly minimal presence within the United States in comparison to the rest of the world. Awareness of its presence and acumen on diagnostics and treatment are essential. Conventional tests are often time consuming, and do not always yield accurate results. We present the case of a patient presenting with fevers but no cough, who eventually found to have large pleural effusion and concluded to have pleural TB without pulmonary parenchymal involvement. He then showed measurable improvement with empiric treatment.

Molecular diagnostics for verification of pleural tuberculosis in Morocco

Pleural tuberculosis (pTB) is a very common form of extrapulmonary tuberculosis (TB). pTB diagnostics represents a major burning challenge worldwide due to the limitations of available conventional diagnostic tools. These latter include microscopic examination of the pleural fluid for acid-fast bacilli, mycobacterial culture of pleural fluid in solid or liquid media, sputum or pleural tissue, and histopathological examination of pleural tissue; these tests have recognized limitations for clinical use. Hence, to overcome these limitations, attention has been devoted to new nucleic acid amplification (NAA) diagnostic tests such as the polymerase chain reaction (PCR) and real-time PCR (RT-PCR), owing to their accuracy, rapidity, high sensitivity and specificity. Within this context, this prospective study was conducted to evaluate the performance of molecular diagnosis methods for differentiation between tuberculosis and non-tuberculosis pleural effusions. Fifty patients with pleural effusion were enrolled in this prospective study in Rabat, Morocco. The efficacy of conventional polymerase chain reaction (PCR) in the diagnostics of tuberculous pleurisy by targeting IS6110 and mycobacterial internal transcribed spacer (MYITS) was evaluated compared to histopathologic examination and culture data. Our results showed that IS6110 PCR could “rule in” pTB, the sensitivity and specificity being 41.6% and 85.7%, respectively. Therefore, the findings confirmed that molecular tests exert a relatively high specificity in EPTB but lower sensitivity, thus a positive test is considered as a pTB case whereas negative one cannot exclude the disease. Although the study was limited by a small sample size, it adds to the body of evidence of usefulness of molecular testing as adjuncts to histopathologic examination for accurate diagnosis of pTB, to treat timely and to avoid the emergence and spread of drug resistant pTB. However, further efforts should be made to increase the sensitivity of NAA methods and to identify the best molecular targets to be useful in clinical practice.

Diagnostic performance of nucleic acid tests in tuberculous pleurisy

BACKGROUND

Tuberculous pleurisy (TBP) is the most common form of extrapulmonary tuberculosis (TB). However, rapid diagnostic methods with high accuracy for tuberculous pleurisy are urgently needed. In the present study, we evaluated the diagnostic accuracy of Xpert MTB/RIF, LAMP and SAT-TB assay with pleural fluids from culture-positive TBP patients.

METHODS

We prospectively enrolled 300 patients with exudative pleural effusions used as the samples for Xpert MTB/RIF, LAMP and SAT-TB assay. Of these, 265 including 223 patients diagnosed with TBP and 42 non-TBP patients used as controls were analyzed.

RESULTS

The sensitivities of Xpert MTB/RIF (27.4%), LAMP (26.5%) and SAT-TB assay (32.3%) were significantly higher than that of pleural effusion smear (14.3%, X² = 20.65, P <  0.001), whereas they were much lower than expected for the analysis of pleural effusion samples. Both SAT-TB assay and Xpert MTB/RIF demonstrated high specificities (100%) and PPVs (100%), but the NPVs of all of the tests were < 22%. The area under ROC curve of pleural effusion smear, LAMP, Xpert MTB/RIF and SAT-TB assays was 0.524 (95% CI 0.431-0.617), 0.632 (95% CI 0.553-0.71), 0.637 (95% CI 0.56-0.714) and 0.673 (95% CI 0.6-0.745). SAT-TB assays had the highest AUC.

CONCLUSION

Nucleic acid amplification tests are not the first choice in the diagnosis of tuberculous pleurisy. In this type of test, SAT-TB is recommended because of its low cost, relatively more accurate compared with the other two tests. This prospective study was approved by The Ethics Committee of the Shanghai Pulmonary Hospital (approval number: K19-148).

TRIAL REGISTRATION

ClinicalTrials.gov identifier: ChiCTR1900026234 (Retrospectively registered). The registration date is September 28, 2019.

Extrapulmonary tuberculosis

Extrapulmonary tuberculosis can be confused with other pathologies because of the variety of symptoms it generates according to the affected organ. So, extrapulmonary tuberculosis must always be taken into account by medical staff within the differential diagnosis. In this paper, a review of the literature on extrapulmonary tuberculosis is carried out with emphasis on the most frequently affected organs.

Label-Free Quantitative Proteomics Identifies Novel Biomarkers for Distinguishing Tuberculosis Pleural Effusion from Malignant Pleural Effusion

PURPOSE

To identify potential protein biomarkers for distinguishing tuberculosis plural effusion (TBPE) from malignant plural effusion (MPE).

EXPERIMENTAL DESIGN

Five independent samples from each group (TBPE and MPE) are enrolled for label-free quantitative proteomics analyses. The differentially expressed proteins are validated by western blot and ELISA. Logistic regression analysis is used to obtain the optimal diagnostic model.

RESULTS

In total, 14 proteins with significant difference are identified between TBPE and MPE. Seven differentially expressed proteins are validated using western blot, and the expression patterns of these seven proteins are similar with those in proteomics analysis. Statistically significant differences in four proteins (AGP1, ORM2, C9, and SERPING1) are noted between TBPE and MPE in the training set (n = 230). Logistic regression analysis shows the combination of AGP1-ORM2-C9 presents a sensitivity of 73.0% (92/126) and specificity of 89.4% (93/104) in discriminating TBPE from MPE. Additional validation is performed to evaluate the diagnostic model in an independent blind testing set (n = 80), and yielded a sensitivity of 74.4% (32/43) and specificity of 91.9% (34/37) in discriminating TBPE from MPE.

CONCLUSION

The study uncovers the proteomic profiles of TBPE and MPE, and provides new potential diagnostic biomarkers for distinguishing TBPE from MPE.

Field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting

INTRODUCTION

The sensitivities of conventional mycobacterial culture in solid or liquid media and acid-fast bacilli (AFB) smear microscopy for Mycobacterium tuberculosis complex (MTBC) detection in extrapulmonary specimens are suboptimal. We evaluated the field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting.

METHODS

The total number of extrapulmonary specimens with mycobacterial culture and PCR results was 566: sterile fluids (n=278), non-sterile fluids (n=147), lymph node material (n=69) tissue biopsies (n=63), and abscess aspirates (n=9). A composite standard consisting of mycobacterial culture results, clinical treatment response to anti-TB drugs, when administered, and histopathology, radiological and laboratory findings were used as a reference for sensitivity and specificity calculations.

RESULTS

Mycobacterial cultures and PCR were positive in 17 and 28 specimens, respectively. The overall agreement between culture and PCR was moderate (Cohen's kappa coefficient: 0.549; P=0.0001). Taking as a reference our composite standard, the sensitivity of the Abbott PCR assay was 77.7%, the specificity 99.5%, the PPV 95.4%, and the NPV 98.8%. In turn, the sensitivity of the mycobacterial culture was 62.9%, the specificity and PPV 100%, and the NPV 97.9%.

CONCLUSION

The good field performance of the Abbott RealTime MTB assay makes it valuable for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting. The use of molecular methods along with culture improves the diagnosis of extrapulmonary tuberculosis.

IgA and IgG antibody detection of mycobacterial antigens in pleural fluid and serum from pleural tuberculous patients

Background

A previous study demonstrated pleural fluid (PF) IgA immunodominance for the fused MT10.3:MPT64 protein in pleural tuberculosis (PLTB) cases. However, no clue on the role of IgA and IgG against this and other antigens in PF and serum concerning improved diagnosis is available. Thus, the aim of the present study was to validate PF IgA-MT10.3:MPT64 and evaluate PF and serum IgA and IgG reactivity against this protein, its peptides (F2) and single MPT64, MT10.3 and the PPE59 mycobacterial specific antigens. IgA and IgG ELISA were measured against the antigen in PLTB (n = 29) and other non-TB pleurisy (n = 39) patient samples.

Results

The immunodominance of PF IgA-MT10.3:MPT64 was confirmed in PLTB (86.2%) followed by PPE59 (62%), while serum IgA-F2 exhibited 51.7% sensitivity. PF and serum IgG-MT10.3:MPT64 led to 65.5 and 51.7% sensitivity, respectively. However, MT10.3 and MPT64 displayed overall lower sensitivity (≤34.5) for both antibodies. All results at 95% fixed specificity. Combinatory results indicated 93.1% sensitivity for PF IgA-MT10.3:MPT64/−PPE59 and IgA/IgG-MT10.3:MPT64 at 92.3% specificity, followed by IgA-MT10.3:MPT64/−MPT64 or /−F2 (89.6%) without jeopardizing specificity (94.9%). The combinatory results of the PF adenosine deaminase test (ADA) and IgA-MT10.3:MPT64/−F2 demonstrated the highest sensitivity (96.6%), with a specificity of 92.3%.

Conclusions

The PF IgA-MT10:MPT64 immune dominance was validated in PLTB, and its combinatory results with PPE59 or MPT64 or F2 antigens as well as with IgG, are reported herein for the first time, improving their potential to assist diagnosis. Combining PF-ADA and IgA-MT10.3:MPT64/−F2 results achieved better accuracy. Moreover, serum IgG, although less accurate, displays potential beyond microbiological tests.

An improved algorithm for rapid diagnosis of pleural tuberculosis from pleural effusion by combined testing with GeneXpert MTB/RIF and an anti-LAM antibody-based assay

Background

This retrospective study evaluated the performance of a lipoarabinomannan (LAM)-based immunological method for diagnosing pleural tuberculosis (TB) from pleural effusion samples. Results were compared to those obtained using conventional culture and molecular testing methods.

Methods

Suspected pleural TB patients who visited Beijing Chest Hospital for medical care between January 2016 and June 2017 were retrospectively analysed in the study. Pleural effusion samples were tested for Mycobacterium tuberculosis (MTB) using the BACTEC MGIT 960 System, GeneXpert, and an anti-LAM antibody assay (LAM assay).

Results

Pleural effusion samples were collected from a total of 219 retrospectively recruited participants suspected of having pleural TB. Thirteen of 155 confirmed pleural TB cases tested positive for MTB via MGIT culture, for a sensitivity of 8.4% [95% confidence interval (CI): 4.0–12.8%]. In addition, GeneXpert and LAM testing identified 22 and 55 pleural TB cases, for sensitivities of 14.2% (95% CI: 8.7–19.7%) and 35.5% (95% CI: 28.1–43.6%), respectively. The specificities of these two assays were 100.0% (95% CI: 92.9–100.0%) and 96.9% (95% CI: 88.2–99.5%), respectively. Combined application of culture and LAM testing identified 60 positive cases, for a sensitivity of 38.7% (95% CI: 31.0–46.4%) that was significantly higher than that of MGIT culture alone (P < 0.01). Similarly, use of LAM testing in combination with GeneXpert led to correct diagnosis of 40.0% (95% CI: 32.3–47.7%) of pleural TB cases, a higher rate than obtained using GeneXpert alone (P < 0.01). In addition, the specificity of the combined assay of GeneXpert and LAM testing was 96.9% (95% CI: 88.2–99.5%). Patients aged 25 to 44 years were more likely to have positive LAM assay results than those ≥65 years of age (P = 0.02). Meanwhile, the proportion of diabetic patients with positive LAM assay results was significantly lower than that of the non-diabetes group (P = 0.03).

Conclusions

An anti-LAM antibody detection assay showed potential for diagnosis of pleural TB from pleural effusion samples. Combined use of the LAM assay with MGIT culture or GeneXpert methods could improve sensitivity for improved pleural TB diagnosis compared to results of individual conventional tests alone.

Diagnostic performance in active TB of QFT-Plus assay and co-expression of CD25/CD134 in response to new antigens of Mycobacterium tuberculosis

The new QuantiFERON-TB Gold Plus employs modified peptides optimized to elicit an IFNγ response from CD8⁺ cytotoxic T lymphocytes in addition to CD4⁺ T cells. With a view to improve the difficult identification of TB cases, we assessed the combination of two specific immunological markers comprising IFNγ secretion and T cells co-expression of CD25 and CD134 in response to Mycobacterium tuberculosis-specific antigens. A total of 34 subjects with suspected TB and 10 age-matched HD were prospectively enrolled. Assessing the performance of QFT-Plus in terms of the TB1 and TB2 results, we found that in TB patients, the quantitative IFNγ value in TB2 was similar to that in TB1, and we did not find any differences irrespective of the disease (pulmonary or extra-pulmonary). The flow cytometric CD25/CD134 assay, allowed a more accurate differentiation between M. tuberculosis-infected and uninfected patients, with a better combination of sensitivity and specificity, especially by evaluation of CD4⁺ T-cell subset. All individuals with negative QFT-Plus results displayed a positive CD25/CD134 response. Overall, a positive correlation was found between T cells co-expressing CD25/CD134 and IFNγ levels in response to both QFT-Plus TB antigen tubes, as well as between the QFT-Plus TB1 and TB2 tubes. We demonstrated that both TB1 and TB2 induce a higher expression of CD25⁺CD134⁺ markers on CD4⁺ T cells among infected TB subjects, compared to the lower degree of CD8⁺ T cells, mainly induced to TB2 stimulation. We suggest that a combined use of classic QFT-Plus and specific CD25/CD134 response may be a useful means in the diagnostic workup for active TB.

A novel aptamer-based test for the rapid and accurate diagnosis of pleural tuberculosis

Pleural tuberculosis (pTB) is diagnosed by using a composite reference standard (CRS) since microbiological methods are grossly inadequate and an accurate diagnostic test remains an unmet need. The present study aimed to evaluate the utility of Mycobacterium tuberculosis (Mtb) antigen and DNA-based tests for pTB diagnosis. Patients were classified as 'Definite TB', 'Probable TB' and 'Non-TB' disease according to the CRS. We assessed the performance of in-house antigen detection assays, namely antibody-based Enzyme-Linked ImmunoSorbent Assay (ELISA) and aptamer-based Aptamer-Linked Immobilized Sorbent Assay (ALISA), targeting Mtb HspX protein and DNA-based tests namely, Xpert MTB/RIF and in-house devR-qPCR. ROC curves were generated for the combined group of 'Definite TB' and 'Probable TB' vs. 'Non-TB' disease group and cut-off values were derived to provide specificity of ≥98%. The sensitivity of ALISA was ∼93% vs. ∼24% of ELISA (p-value ≤0.0001). devR-qPCR exhibited a sensitivity of 50% vs. ∼22% of Xpert (p-value ≤0.01). This novel aptamer-based ALISA test surpasses the sensitivity criterion and matches the specificity requirement spelt out in the 'Target product profile' for extrapulmonary tuberculosis samples by Unitaid (Sensitivity ≥80%, Specificity 98%). The superior performance of the aptamer-based ALISA test indicates its translational potential to bridge the existing gap in pTB diagnosis.