Evaluation of Xpert MTB/RIF assay performance in diagnosing extrapulmonary tuberculosis among adults in a tertiary care centre in India

Laparoscopic and hysteroscopic findings in women with sub-fertility and tuberculosis: A case series

OBJECTIVE

Evaluation of hysteroscopic and laparoscopic findings in subfertile women predictive of tuberculosis.

DESIGN

Retrospective case series analysis.

SETTING

Tertiary hospital in India.

POPULATION

A retrospective analysis of 16 784 subfertile women who had undergone diagnostic hysterolaparoscopy (DHL) was conducted between February 2014 and June 2021.

METHODS

Histopathological evidence, acid-fast bacilli (AFB), culture and GeneXpert MTB/RIF assay were used to diagnose female genital tuberculosis (FGTB). Various hysteroscopic and laparoscopic findings were analysed, and a binary logistic regression assessed associations between these findings and positive diagnostic outcomes.

MAIN OUTCOME MEASURES

Various hysteroscopic and laparoscopic findings correspond to tubercular manifestation.

RESULTS

Of the 16,784 patients, 1083 had hysteroscopy and laparoscopy findings suggestive of tuberculosis, and 309 were diagnosed with FGTB based on diagnostic tests. Logistic regression identified variables strongly predictive of positive status outcomes; tuberculous abdomino-pelvic adhesions of various grades, isthmo-ampullary block, tubercle, tubo-ovarian mass, tuberculous hydrosalpinx, complete tubal destruction, tubal diverticula and rigid tube emerged as strong predictors.

CONCLUSIONS

Logistic regression-derived predictors, alongside specific laparoscopic and hysteroscopic findings, can enhance diagnostic accuracy and clinical decision-making to start antitubercular therapy in subfertile women.

Detection of drug-resistant Mycobacterium tuberculosis in pericardial fluid culture and its correlation with cartridge based nucleic acid amplification test and adenosine deaminase activity

BACKGROUND

Pericardial effusion is the accumulation of fluid in the pericardial cavity. In nations with high tuberculosis (TB) load, TB is the most common cause of pericardial effusion. 1-2% of patients with pulmonary TB develop Pericardial TB worldwide. Multi-drug-resistant (MDR) TB, including extrapulmonary TB (EPTB) cases, are rising in number. Adenosine Deaminase (ADA) is an enzyme in lymphocytes and myeloid cells, which has certain immune functions in the body. ADA levels are increased in inflammatory conditions, like pleural, pericardial, or joint effusions, of bacterial etiology, granulomatous conditions, neoplasms, and autoimmune pathologies. TB is the only lymphocytosis involving disease with increased ADA levels. MDR EPTB is rare, but cases are on the rise, and tuberculous pericardial effusion is one such example. Hence, it is important to know the percentage of cases detected by a culture that can be identified by cartridge-based nucleic acid amplification test (CBNAAT), their resistance patterns, and to identify potential markers like ADA, which can help in early identification of cases. The objectives of this study were to identify the Mycobacterium tuberculosis (MTB) bacilli in culture, and correlate them with cartridge-based nucleic acid amplification test (CBNAAT) results and their drug-resistance, in the Pericardial tubercular effusion, and to find if Adenosine Deaminase (ADA) levels can be used as a predictor of the presence of MTB in pericardial fluid.

METHODOLOGY

We enrolled 52 patients with moderate to large tuberculous pericardial effusion, based on pericardial fluid analysis, CBNAAT, and culture methods, between January 2021 and December 2021.

RESULTS

The mean age of the patients was 41.85 + 17.88 years, with a median of 38 years. Males made up 57.7% of the total patients. MTB was detected in 16 (30.8%) patients in the CBNAAT evaluations. 14 (87.5%) of the CBNAAT-positive TB patients were sensitive to Rifampicin, whereas the remaining 2 (12.5%) were resistant to Rifampicin on CBNAAT. MTB was found to be growing in 8 (15.38%) drug sensitivity test cultures. Out of these 8, 6 were sensitive to first-line drugs, whereas 2 were resistant to both Isoniazid and Rifampicin. The presence of cough was found to have a significant difference between CBNAAT-detected MTB positive and negative patients (p = 0.020), whereas an insignificant difference was found for the presence of hypertension, diabetes mellitus, obesity, dyspnea, or fever. There was also an insignificant difference between the number of patients positive for the Tuberculin skin test, between the two groups. ADA was significantly higher in the MTB-detected CBNAAT group (85.91 + 37.60U/L vs 39.78 + 24.31U/L, p = 0.005), whereas the total leukocyte count, lymphocytes, neutrophils, random blood sugar levels, and serum protein levels had no significant difference. The area under the Receiver Operator Curve (CBNAAT positive: dependent variable; ADA: test result variable) was 0.854 (null hypothesis rejected), with a standard error of 0.078.

CONCLUSIONS

Culture is the gold standard method to diagnose tuberculosis. Detection of MTB on pericardial fluid culture is very uncommon, though in our study, culture came out positive in 16% of patients, and 4% were resistant to rifampicin and isoniazid. Higher ADA levels in pericardial fluid are an indicator of tuberculous pericardial effusion.

Analysis of the Effect of Female Genital Tuberculosis on Ovarian Reserve Parameters

Background

Female genital tuberculosis (FGTB) is a known cause of female infertility. Worldwide incidence is 5%-10% and annual burden in India is around 4%-7%. It is known to cause tubal and endometrial damage. However, the effect on ovarian damage is poorly known. The availability of ovarian markers has contributed to an improved understanding of ovarian reserve in FGTB.

Aims

The aim of this study was to assess ovarian reserve by measuring anti-Mullerian hormone (AMH) and antral follicle count (AFC) amongst infertile women and analyse the effect of GTB on ovarian reserve parameters.

Settings and Design

This was a prospective study at a tertiary referral centre for infertility for 18 months.

Materials and Methods

A total of 133 infertile women who underwent diagnostic hysterolaparoscopy and cartridge-based nucleic acid amplification test testing of an endometrial biopsy were included in the study. AMH and AFC of all the infertile women were assessed and compared between cases with and without FGTB.

Statistical Analysis Used

Independent t-test was used to find the outcome differences in the distribution of values. P < 0.05 was considered statistically significant.

Results

Fifty-eight (43.6%) cases were diagnosed with FGTB (Group I), and 75 (56.3%) cases were without FGTB (Group II). The mean AMH level 1.88 ng/ml (±1.52) and mean AFC 9.0 (±5.50) were significantly lower (P < 0.001) in Group I than in Group II with AMH 3.57 ng/ml (±2.93) and AFC 12.50 (±6.0).

Conclusion

In women with prolonged infertility and low ovarian reserve, FGTB should be ruled out. Early diagnosis and treatment of GTB may prevent further decline of ovarian reserve and improve the reproductive outcome.

Soft tissue tuberculosis detected by next-generation sequencing: A case report and review of literature

BACKGROUND

Soft tissue tuberculosis is rare and insidious, with most patients presenting with a localized enlarged mass or swelling, which may be factors associated with delayed diagnosis and treatment. In recent years, next-generation sequencing has rapidly evolved and has been successfully applied to numerous areas of basic and clinical research. A literature search revealed that the use of next-generation sequencing in the diagnosis of soft tissue tuberculosis has been rarely reported.

CASE SUMMARY

A 44-year-old man presented with recurrent swelling and ulcers on the left thigh. Magnetic resonance imaging suggested a soft tissue abscess. The lesion was surgically removed and tissue biopsy and culture were performed; however, no organism growth was detected. Finally, Mycobacterium tuberculosis was confirmed as the pathogen responsible for infection through next-generation sequencing analysis of the surgical specimen. The patient received a standardized anti-tuberculosis treatment and showed clinical improvement. We also performed a literature review on soft tissue tuberculosis using studies published in the past 10 years.

CONCLUSION

This case highlights the importance of next-generation sequencing for the early diagnosis of soft tissue tuberculosis, which can provide guidance for clinical treatment and improve prognosis.

To Study the Role of Cartridge-Based Nucleic Acid Amplification Test (CBNAAT) in Early Diagnosis of Extra Pulmonary Tuberculosis

Diagnosing EPTB is difficult as various clinical presentations are seen with paucibacillary nature of the disease. Maurya AK et al. (J Postgrad Med 58(3):185-189) AFB smear hasn't been much effective in diagnosing of EPTB. Tuberculosis of head and neck diagnosis can be missed due to large number of smear negative cases, leading false negative cases increase. CBNAAT is cartridge-based nucleic acid amplification test which detects the presence of TB bacilli this study we have examined the effectiveness of CBNAAT for diagnosing EPTB with cervical lymphadenitis and compared with Sputum AFB Microscopy smear. Aims and objective 1.To study the role of cartridge-based nucleic acid amplification test (CBNAAT) in early diagnosis of extra pulmonary tuberculosis. 2 Comparative analysis of CBNAAT with AFB smears in EPTB. Type of Study Descriptive retrospective observational study was done at the department of ENT and Head & surgery, A.B.V. Govt medical college, Vidisha, M.P, India. Result Out of 184 patients 43 samples were AFB smear positive and 141 were negative. In CBNAAT 88 out of 184 and 96 were found to be negative.32 patients were negative on Sputum microscopy AFB analysis but found to be positive on CBNAAT. Sensitivity of CBNAAT was 86% AFB 64%, Specificity of CBNAAT, AFB is 91% and 89% respectively. Our study finds that CBNAAT is much more effective in diagnosis of EPTB with cervical lymphadenitis when compared to AFB smear microscopy alone.

Female Genital Tuberculosis

Female genital tuberculosis (FGTB) is an important cause of morbidity and infertility worldwide. Mycobacterium tuberculosis most commonly spreads to the genital tract from a focus elsewhere in the body and affects the bilateral fallopian tubes and/or endometrium. Many patients with FGTB have indolent disease and are only diagnosed after evaluation for infertility. Women may present with menstrual irregularities, lower abdominal or pelvic pain, or abnormal vaginal discharge. Given the low sensitivity of diagnostic tests, various composite reference standards are used to diagnose FGTB, including some combination of endoscopic findings, microbiological or molecular testing, and histopathological evidence in gynecological specimens. Early treatment with a standard regimen of a 2-month intensive phase with isoniazid, rifampin, ethambutol, and pyrazinamide, followed by a 4-month continuation phase with isoniazid and rifampin, is recommended to prevent irreversible organ damage. However, even with treatment, FGTB can lead to infertility or pregnancy-related complications, and stigma is pervasive.

Effectiveness of Xpert MTB/RIF for the diagnosis of extrapulmonary tuberculosis at various stand-alone laboratories in Delhi

BACKGROUND

Globally, EPTB accounts for 15% of the notified incident TB cases. Laboratory confirmation of EPTB is challenging and majority of the cases remain undetected for a longer time. A major breakthrough in the diagnosis of EPTB was the introduction of nucleic acid amplification tests (NAAT). One such test-the Xpert MTB/RIF assay also known as Cartridge based nucleic acid amplification test (CBNAAT) was endorsed by the Scientific and Technical Advisory Board of the WHO for the diagnosis of Tuberculosis. The present study was conduct to evaluate the outcome of various extrapulmonary samples tested in the year 2019 at different standalone NAAT laboratories in Delhi.

MATERIALS AND METHODS

A total of 20,238 samples consisting mainly of Pus (21.77%), Cerebrospinal fluid (CSF) (14.96%), Biopsies (13.87%), Pleural fluid (10.49%), Lymph node aspirations (FNAC aspirates) (6.75%), synovial fluid (0.54%) and gastric aspirates (26.4%) tested at 22 standalone NAAT laboratories were included in this study.

RESULTS

Mycobacterium tuberculosis was detected in 3496 samples and resistance to rifampicin was detected in 329 of the samples. The overall yield of all the specimens combined was 17.2%. Highest yield was seen in Lymph nodes aspirates (FNAC) (36.0%), followed by pus (35.4%), tissues (15.7%), synovial fluid (13.5%), Endometrial tissues (10.7%), Pleural fluid (9.5%), Gastric aspirates (9.4%) and CSF (6.5%). The lowest yield was seen in Cavitary fluids (6.2%).

CONCLUSION

The results of this study highlight the usefulness of Xpert MTB/RIF assay in the diagnosis of EPTB. In particular, this assay proved to be of great utility while testing pus samples, tissue samples and lymph node FNACs.

Xpert MTB/RIF Ultra versus Xpert MTB/RIF for diagnosis of tuberculous pleural effusion: A systematic review and comparative meta-analysis

Objective

We compared diagnostic accuracy of pleural fluid Xpert MTB/RIF (Xpert) and Xpert MTB/RIF Ultra (Ultra) assays for diagnosing tuberculous pleural effusion (TPE), through systematic review and comparative meta-analysis.

Methods

We searched PubMed and Embase databases for publications reporting diagnostic accuracy of Xpert or Ultra for TPE. We used bivariate random-effects modeling to summarize diagnostic accuracy information from individual studies using either mycobacterial culture or composite criteria as reference standard. We performed meta-regression through hierarchical summary receiver operating characteristic (HSROC) modeling to evaluate comparative performance of the two tests from studies reporting diagnostic accuracy of both in the same study population.

Results

We retrieved 1097 publications, and included 74 for review. Summary estimates for sensitivity and specificity for Xpert were 0.52 (95% CI 0.43–0.60, I² 82.1%) and 0.99 (95% CI 0.97–0.99, I² 85.1%), respectively, using culture-based reference standard; and 0.21 (95% CI 0.17–0.26, I² 81.5%) and 1.00 (95% CI 0.99–1.00, I² 37.6%), respectively, using composite reference standard. Summary estimates for sensitivity and specificity for Ultra were 0.68 (95% CI 0.55–0.79, I² 80.0%) and 0.97 (95% CI 0.97–0.99, I² 92.1%), respectively, using culture-based reference standard; and 0.47 (95% CI 0.40–0.55, I² 64.1%) and 0.98 (95% CI 0.95–0.99, I² 54.8%), respectively, using composite reference standard. HSROC meta-regression yielded relative diagnostic odds ratio of 1.28 (95% CI 0.65–2.50) and 1.80 (95% CI 0.41–7.84) respectively in favor of Ultra, using culture and composite criteria as reference standard.

Conclusion

Ultra provides superior diagnostic accuracy over Xpert for diagnosing TPE, mainly because of its higher sensitivity.

Bayesian latent class analysis produced diagnostic accuracy estimates that were more interpretable than composite reference standards for extrapulmonary tuberculosis tests

BACKGROUND

Evaluating the accuracy of extrapulmonary tuberculosis (TB) tests is challenging due to lack of a gold standard. Latent class analysis (LCA), a statistical modeling approach, can adjust for reference tests' imperfect accuracies to produce less biased test accuracy estimates than those produced by commonly used methods like composite reference standards (CRSs). Our objective is to illustrate how Bayesian LCA can address the problem of an unavailable gold standard and demonstrate how it compares to using CRSs for extrapulmonary TB tests.

METHODS

We re-analyzed a dataset of presumptive extrapulmonary TB cases in New Delhi, India, for three forms of extrapulmonary TB. Results were available for culture, smear microscopy, Xpert MTB/RIF, and a non-microbiological test, cytopathology/histopathology, or adenosine deaminase (ADA). A diagram was used to define assumed relationships between observed tests and underlying latent variables in the Bayesian LCA with input from an inter-disciplinary team. We compared the results to estimates obtained from a sequence of CRSs defined by increasing numbers of positive reference tests necessary for positive disease status.

RESULTS

Data were available from 298, 388, and 230 individuals with presumptive TB lymphadenitis, meningitis, and pleuritis, respectively. Using Bayesian LCA, estimates were obtained for accuracy of all tests and for extrapulmonary TB prevalence. Xpert sensitivity neared that of culture for TB lymphadenitis and meningitis but was lower for TB pleuritis, and specificities of all microbiological tests approached 100%. Non-microbiological tests' sensitivities were high, but specificities were only moderate, preventing disease rule-in. CRSs' only provided estimates of Xpert and these varied widely per CRS definition. Accuracy of the CRSs also varied by definition, and no CRS was 100% accurate.

CONCLUSION

Unlike CRSs, Bayesian LCA takes into account known information about test performance resulting in accuracy estimates that are easier to interpret. LCA should receive greater consideration for evaluating extrapulmonary TB diagnostic tests.

Genital footprints of extragenital tuberculosis in infertile women: Comparison of various diagnostic modalities

BACKGROUND

Genital tuberculosis (TB) continues to remain an important cause of infertility in women, especially in developing countries. It is mostly consequent to a primary infection elsewhere in the body. The diagnosis is challenging, considering its paucibacillary nature. Although there are many studies on association of genital tuberculosis with infertility, there is paucity of literature on impact of extragenital tuberculosis on fertility of women through involvement of female reproductive organs. The various diagnostic modalities available have limitations and quest is ongoing for the best diagnostic test.

METHOD

This was a prospective observational study conducted at the infertility clinic of a tertiary care health facility where 60 infertile women with either tubal factor or unexplained infertility with or without past history of extragenital tuberculosis were enrolled as study subjects or controls respectively. Mantoux test was performed in all women and diagnostic laparo-hysteroscopy was performed in all women to look for any evidence of uterine and/or tubal damage. The peritoneal fluid was sent for GeneXpert and Liquid culture for mycobacterium tuberculosis. Results of Mantoux test, GeneXpert and liquid culture were compared with the laparohysteroscopic findings.

RESULT

Of the thirty infertile women in the study group, 27/30 (90%) had a history of pulmonary tuberculosis and 3/30 (10%) had history of tubercular cervical lymphadenopathy. It was observed that Mantoux test was positive (induration >10 mm) in 27/30 (90%) of women in the study group as compared to only 4/30 (13.3%) controls. Abnormal hysteroscopic findings were documented in 26.6% (8/30) study group women as compared to 6.6% (2/30) women in the control group. Similarly, 60% (18/30) of women in the study group had abnormal laparoscopic findings compared to 33% (10/30) in the control group. Seven out of thirty (23.3%) women were positive for GeneXpert in the study group compared to only 1/30 (3.3%) in the control group. Similarly, liquid culture was positive in 6/30 (20%) of women in the study group as compared to 1/30 (3.3%) in the control group. All the above differences were statistically significant. We observed that the sensitivity of Mantoux test (75.8%) stand alone was higher than the other tests combined (50%). However, specificity and positive predictive value (PPV) increases markedly (up to 100%) to when all the three tests are combined.

CONCLUSION

The authors conclude that all women presenting with infertility should be screened for a past history of tuberculosis and actively worked up for genital tuberculosis in case the history is positive. The various available tests (Mantoux test, GeneXpert and liquid culture) have their limitations for the diagnosis of genital tuberculosis. Thus an approach of early resort to laparohysteroscopy in suspected patients is desirable so that definitive management may be instituted timely and promptly.

Diagnostic role of Xpert-MTB RIF assay in osteoarticular tuberculosis: A retrospective study

BACKGROUND

Osteoarticular tuberculosis (OATB) is a severe form of extrapulmonary tuberculosis (TB), which causes notable morbidity and warrants a high index of suspicion for prompt management. The diagnosis of OATB poses a challenge, because of the difficulty of collecting the samples and, secondarily, the paucibacillary nature of lesion, which gives poor sensitivity and reproducibility, with long turnaround time of routine/conventional laboratory tests and the requirement for invasive procedures and expertise. The Xpert MTB/RIF assay has been approved by the World Health Organization as a rapid diagnostic tool for diagnosing pulmonary and extrapulmonary TB.

AIM

To emphasize the diagnostic efficiency of gene Xpert for OATB in suspected patients in a tertiary care hospital of Eastern India.

METHODS

This retrospective study was conducted in the Department of Microbiology and Orthopaedics by analyzing the data of the gene Xpert assay over a 3-year duration from January 2018 to February 2021. Demographic and clinical data were recorded. The diagnostic efficiency of gene Xpert was evaluated against the composite reference standard (CRS).

RESULTS

A total of 37 cases fell into positive, probable, and possible categories of osteoarticular TB out of 112 patients included in the study by CRS; gene Xpert result was positive in 35 out of the 37 different CRS categorized cases. Of the 112 cases, culture was put in 40 cases, and, of these cultures, 5 cases showed the growth of MTB. Of these, 4 cases were included in the 35 cases diagnosed by gene Xpert. Smear microscopy was positive in 6 out of 37 CRS categorized cases. When compared with CRS, the sensitivity of gene Xpert assay, culture, and smear was found to be 94.6%, 13.5%, and 16.2%, respectively, while specificity in all the three types of tests was 100%. When kappa statistics were applied, the percentage of agreement gene Xpert, culture, and microscopy with CRS was found to be 95%, 20%, and 22.6%, respectively. Follow-up of the gene Xpert positive patients after getting anti-tubercular treatment revealed improved conditions.

CONCLUSION

Gene Xpert could detect 31 extra cases with a low and very low mycobacterial load that were missed by the routine culture methods. Hence, more samples should be processed for molecular diagnostic methods like gene Xpert along with other conventional methods for the validation of the molecular test prospectively for the timely diagnosis of osteoarticular TB.

Diagnostic accuracy of the Xpert MTB/RIF assay for tuberculous pericarditis: A systematic review and meta-analysis

Objective

The purpose of this study was to evaluate the diagnostic efficacy of Xpert MTB/RIF for tuberculous pericarditis (TBP).

Methods

We searched relevant databases for Xpert MTB/RIF for TBP diagnosis until April 2021 and screened eligible studies for study inclusion. We evaluated the effectiveness of Xpert MTB/RIF when the composite reference standard (CRS) and mycobacterial culture were the gold standards, respectively. We performed meta-analyses using a bivariate random-effects model, and when the heterogeneity was obvious, the source of heterogeneity was further discussed.

Results

We included seven independent studies comparing Xpert MTB/RIF with the CRS and six studies comparing it with culture. The pooled sensitivity, specificity, and area under the curve of Xpert MTB/RIF were 65% (95% confidence interval, 59–72%), 99% (97–100%), and 0.99 (0.97–0.99) as compared with the CRS, respectively, and 75% (53–88%), 99% (90–100%), and 0.94 (0.92–0.96) as compared with culture, respectively. There was no significant heterogeneity between studies when CRS was the gold standard, whereas heterogeneity was evident when culture was the gold standard.

Conclusions

The sensitivity of Xpert MTB/RIF for diagnosing TBP was moderate and the specificity was good; thus, Xpert MTB/RIF can be used in the initial diagnosis of TBP.

Extrapulmonary tuberculosis

Introduction: Tuberculosis (TB) is a major cause of morbidity and mortality globally. Extrapulmonary TB (EPTB) constitutes about 15%-20% of all TB patients, but accounts for 50% among HIV-coinfected. Confirmation of microbial diagnosis of EPTB is usually challenging.Areas covered: Availability of newer imaging modalities like ¹⁸FDG-PET-CT and PET-MRI has facilitated precise anatomical localization of the lesions and mapping the extent of EPTB. The use of image- and endoscopy-guided invasive diagnostic methods has made procurement of tissue/body fluids for diagnostic testing possible. With the advent of universal drug-susceptibility testing, a rapid diagnosis of drug-resistance is now possible in EPTB. Drug-susceptible EPTB usually responds well to first-line anti-TB treatment; TB meningitis, bone and joint TB and lymph node TB requires longer durations of treatment.Expert opinion: Adjunctive use of corticosteroids in the initial period is recommended in the central nervous system and pericardial TB. Surgical intervention is helpful to obtain tissue samples for diagnosis. Adjunctive surgical treatment along with medical treatment is useful in treating complications like hydrocephalus, Pott's spine. Follow-up of EPTB patients is crucial as treatment period is usually prolonged, requires recognition of development of immune reconstitution and inflammatory syndrome (IRIS), monitoring of adverse events, serious adverse events like anti-TB drug-induced hepatotoxicity, organ-related complications, and treatment adherence.

HIV TB coinfection - perspectives from India

Introduction: HIV and tuberculosis (TB) are two of the most challenging infections faced by humanity and place immense burden on health care systems worldwide. Both HIV and TB impact one another's progression.Areas covered: HIV is the most important risk factor for progression of latent TB to active disease. TB is the most common cause of death among People Living with HIV (PLHIV). Timely detection of TB among PLHIV and screening for HIV among TB patients, early initiation of ART and ATT among coinfected persons, provision of CPT and TB Preventive therapy along with control of air-borne infection are some of the key activities to reduce morbidity and mortality among coinfected persons. Despite many challenges, the collaboration between two programs has yielded good results and globally more than 7.3 million lives of PLHIV have been saved globally through scale-up of collaborative TB/HIV activities since 2005. The review looked into key features of both programs that are the collaboration strategies and challenges that still need to be addressed.Expert opinion: The overarching principle for effective implementation of collaborative activities is integration of the TB and HIV national programs right from policy making to service delivery and monitoring.

Limited role of GeneXpert in peritoneal fluid in the diagnosis of genital tuberculosis in infertile women

Background and Objectives:

Genital tuberculosis (TB) is an important cause of infertility in women that poses many challenges in diagnosis. The study is done to understand the utility of GeneXpert test in peritoneal fluid in the diagnosis of genital TB in infertile women.

Methods:

All infertile women in postmenstrual phase who were planned for laparoscopy in study period were included. Women who were already on anti-TB therapy were excluded. Peritoneal fluid/washings were retrieved during laparoscopy to test for Mycobacterium tuberculosis by GeneXpert. A note was made of laparoscopy evidence of TB. Endometrial sample was sent for microbiological testing of mycobacterium on smear and liquid culture. Histopathological test of endometrium was also done to look for granulomas.

Results:

In a total of 57 women, 8 (14.03%) women were diagnosed with TB on the basis of laparoscopy or microbiological or histopathological tests. Six women had caseating tubercles in pelvis, of them two women had presence of mycobacterium on smear, one woman also had positive liquid culture. In two women endometrial smear was positive. None of the women had a positive GeneXpert test in peritoneal fluid.

Conclusion:

Genital TB is a clinical problem in infertile women. Even in women with confirmed genital TB the peritoneal fluid/washings were negative for mycobacterium. GeneXpert did not pick Mycobacterium in peritoneal fluid in women with genital TB. Hence, it is not a sensitive and good tool for the diagnosis of female genital TB.

Comparative Performance of Line Probe Assay (Version 2) and Xpert MTB/RIF Assay for Early Diagnosis of Rifampicin-Resistant Pulmonary Tuberculosis

BACKGROUND

The emergence of drug-resistant tuberculosis (TB), is a major menace to cast off TB worldwide. Line probe assay (LPA; GenoType MTBDRplus ver. 2) and Xpert MTB/RIF assays are two rapid molecular TB detection/diagnostic tests. To compare the performance of LPA and Xpert MTB/RIF assay for early diagnosis of rifampicin-resistant (RR) TB in acid-fast bacillus (AFB) smear-positive and negative sputum samples.

METHODS

A total 576 presumptive AFB patients were selected and subjected to AFB microscopy, Xpert MTB/RIF assay and recent version of LPA (GenoType MTBDRplus assay version 2) tests directly on sputum samples. Results were compared with phenotypic culture and drug susceptibility testing (DST). DNA sequencing was performed with rpoB gene for samples with discordant rifampicin susceptibility results.

RESULTS

Among culture-positive samples, Xpert MTB/RIF assay detected Mycobacterium tuberculosis (Mtb) in 97.3% (364/374) of AFB smear-positive samples and 76.5% (13/17) among smear-negative samples, and the corresponding values for LPA test (valid results with Mtb control band) were 97.9% (366/374) and 58.8% (10/17), respectively. For detection of RR among Mtb positive molecular results, the sensitivity of Xpert MTB/RIF assay and LPA (after resolving discordant phenotypic DST results with DNA sequencing) were found to be 96% and 99%, respectively. Whereas, specificity of both test for detecting RR were found to be 99%.

CONCLUSION

We conclude that although Xpert MTB/RIF assay is comparatively superior to LPA in detecting Mtb among AFB smear-negative pulmonary TB. However, both tests are equally efficient in early diagnosis of AFB smear-positive presumptive RR-TB patients.

Xpert MTB/RIF Ultra and Xpert MTB/RIF assays for extrapulmonary tuberculosis and rifampicin resistance in adults

BACKGROUND

Xpert MTB/RIF Ultra (Xpert Ultra) and Xpert MTB/RIF are World Health Organization (WHO)-recommended rapid nucleic acid amplification tests (NAATs) widely used for simultaneous detection of Mycobacterium tuberculosis complex and rifampicin resistance in sputum. To extend our previous review on extrapulmonary tuberculosis (Kohli 2018), we performed this update to inform updated WHO policy (WHO Consolidated Guidelines (Module 3) 2020).

OBJECTIVES

To estimate diagnostic accuracy of Xpert Ultra and Xpert MTB/RIF for extrapulmonary tuberculosis and rifampicin resistance in adults with presumptive extrapulmonary tuberculosis.

SEARCH METHODS

Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, Latin American Caribbean Health Sciences Literature, Scopus, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, the International Standard Randomized Controlled Trial Number Registry, and ProQuest, 2 August 2019 and 28 January 2020 (Xpert Ultra studies), without language restriction.

SELECTION CRITERIA

Cross-sectional and cohort studies using non-respiratory specimens. Forms of extrapulmonary tuberculosis: tuberculous meningitis and pleural, lymph node, bone or joint, genitourinary, peritoneal, pericardial, disseminated tuberculosis. Reference standards were culture and a study-defined composite reference standard (tuberculosis detection); phenotypic drug susceptibility testing and line probe assays (rifampicin resistance detection).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias and applicability using QUADAS-2. For tuberculosis detection, we performed separate analyses by specimen type and reference standard using the bivariate model to estimate pooled sensitivity and specificity with 95% credible intervals (CrIs). We applied a latent class meta-analysis model to three forms of extrapulmonary tuberculosis. We assessed certainty of evidence using GRADE.

MAIN RESULTS

69 studies: 67 evaluated Xpert MTB/RIF and 11 evaluated Xpert Ultra, of which nine evaluated both tests. Most studies were conducted in China, India, South Africa, and Uganda. Overall, risk of bias was low for patient selection, index test, and flow and timing domains, and low (49%) or unclear (43%) for the reference standard domain. Applicability for the patient selection domain was unclear for most studies because we were unsure of the clinical settings. Cerebrospinal fluid Xpert Ultra (6 studies) Xpert Ultra pooled sensitivity and specificity (95% CrI) against culture were 89.4% (79.1 to 95.6) (89 participants; low-certainty evidence) and 91.2% (83.2 to 95.7) (386 participants; moderate-certainty evidence). Of 1000 people where 100 have tuberculous meningitis, 168 would be Xpert Ultra-positive: of these, 79 (47%) would not have tuberculosis (false-positives) and 832 would be Xpert Ultra-negative: of these, 11 (1%) would have tuberculosis (false-negatives). Xpert MTB/RIF (30 studies) Xpert MTB/RIF pooled sensitivity and specificity against culture were 71.1% (62.8 to 79.1) (571 participants; moderate-certainty evidence) and 96.9% (95.4 to 98.0) (2824 participants; high-certainty evidence). Of 1000 people where 100 have tuberculous meningitis, 99 would be Xpert MTB/RIF-positive: of these, 28 (28%) would not have tuberculosis; and 901 would be Xpert MTB/RIF-negative: of these, 29 (3%) would have tuberculosis. Pleural fluid Xpert Ultra (4 studies) Xpert Ultra pooled sensitivity and specificity against culture were 75.0% (58.0 to 86.4) (158 participants; very low-certainty evidence) and 87.0% (63.1 to 97.9) (240 participants; very low-certainty evidence). Of 1000 people where 100 have pleural tuberculosis, 192 would be Xpert Ultra-positive: of these, 117 (61%) would not have tuberculosis; and 808 would be Xpert Ultra-negative: of these, 25 (3%) would have tuberculosis. Xpert MTB/RIF (25 studies) Xpert MTB/RIF pooled sensitivity and specificity against culture were 49.5% (39.8 to 59.9) (644 participants; low-certainty evidence) and 98.9% (97.6 to 99.7) (2421 participants; high-certainty evidence). Of 1000 people where 100 have pleural tuberculosis, 60 would be Xpert MTB/RIF-positive: of these, 10 (17%) would not have tuberculosis; and 940 would be Xpert MTB/RIF-negative: of these, 50 (5%) would have tuberculosis. Lymph node aspirate Xpert Ultra (1 study) Xpert Ultra sensitivity and specificity (95% confidence interval) against composite reference standard were 70% (51 to 85) (30 participants; very low-certainty evidence) and 100% (92 to 100) (43 participants; low-certainty evidence). Of 1000 people where 100 have lymph node tuberculosis, 70 would be Xpert Ultra-positive and 0 (0%) would not have tuberculosis; 930 would be Xpert Ultra-negative and 30 (3%) would have tuberculosis. Xpert MTB/RIF (4 studies) Xpert MTB/RIF pooled sensitivity and specificity against composite reference standard were 81.6% (61.9 to 93.3) (377 participants; low-certainty evidence) and 96.4% (91.3 to 98.6) (302 participants; low-certainty evidence). Of 1000 people where 100 have lymph node tuberculosis, 118 would be Xpert MTB/RIF-positive and 37 (31%) would not have tuberculosis; 882 would be Xpert MTB/RIF-negative and 19 (2%) would have tuberculosis. In lymph node aspirate, Xpert MTB/RIF pooled specificity against culture was 86.2% (78.0 to 92.3), lower than that against a composite reference standard. Using the latent class model, Xpert MTB/RIF pooled specificity was 99.5% (99.1 to 99.7), similar to that observed with a composite reference standard. Rifampicin resistance Xpert Ultra (4 studies) Xpert Ultra pooled sensitivity and specificity were 100.0% (95.1 to 100.0), (24 participants; low-certainty evidence) and 100.0% (99.0 to 100.0) (105 participants; moderate-certainty evidence). Of 1000 people where 100 have rifampicin resistance, 100 would be Xpert Ultra-positive (resistant): of these, zero (0%) would not have rifampicin resistance; and 900 would be Xpert Ultra-negative (susceptible): of these, zero (0%) would have rifampicin resistance. Xpert MTB/RIF (19 studies) Xpert MTB/RIF pooled sensitivity and specificity were 96.5% (91.9 to 98.8) (148 participants; high-certainty evidence) and 99.1% (98.0 to 99.7) (822 participants; high-certainty evidence). Of 1000 people where 100 have rifampicin resistance, 105 would be Xpert MTB/RIF-positive (resistant): of these, 8 (8%) would not have rifampicin resistance; and 895 would be Xpert MTB/RIF-negative (susceptible): of these, 3 (0.3%) would have rifampicin resistance.

AUTHORS' CONCLUSIONS

Xpert Ultra and Xpert MTB/RIF may be helpful in diagnosing extrapulmonary tuberculosis. Sensitivity varies across different extrapulmonary specimens: while for most specimens specificity is high, the tests rarely yield a positive result for people without tuberculosis. For tuberculous meningitis, Xpert Ultra had higher sensitivity and lower specificity than Xpert MTB/RIF against culture. Xpert Ultra and Xpert MTB/RIF had similar sensitivity and specificity for rifampicin resistance. Future research should acknowledge the concern associated with culture as a reference standard in paucibacillary specimens and consider ways to address this limitation.

Validity of a CB-NAAT assay in diagnosing tuberculosis in comparison to culture: A study from an urban area of South India

•CB-NAAT performance compared in 831 suspected pulmonary and extrapulmonary suspected cases.•The conventional stained smear and CB-NAAT results were compared to the MGIT culture.•Sensitivity and specificity of CB-NAAT was 84.43% and 94.93%.•The rapid results from CB-NAAT confirms its use in the tuberculosis diagnostic algorithm.•The benefits of disease diagnosis and prevention outweighs the price tag of the CB-NAAT tests.•This is more so for the resource poor countries where the burden of the disease is high.

Evaluation of Gene Xpert as compared to conventional methods in diagnosis of Female Genital Tuberculosis

To evaluate Gene Xpert for diagnosis of Female Genital Tuberculosis (FGTB) as compared to conventional methods.

STUDY DESIGN

It was a prospective study conducted over 167 cases of infertile female genital tuberculosis (FGTB) diagnosed on composite reference standard (CRS) (smear for AFB, histopathological evidence of epithelioid granuloma or definite or possible findings of tuberculosis on laparoscopy). All women underwent endometrial biopsy for AFB microscopy, culture, gene Xpert, PCR and histopathology) and laparoscopy and hysteroscopy for diagnosis and prognostication of disease. The results of Gene Xpert were compared with conventional methods in detection of FGTB. All patients were treated with 6 months course of rifampicin (R), isoniazid (H), pyrazinamide (Z) and ethambutol (E) (RHZE for 2 months, RHE for 4 months) using directly observed treatment short course strategy.

RESULTS

Mean age, parity, body mass index and history of contact was 28.3 years, 0.28, 22.9 Kg/m² and 38.92% respectively. Primary infertility was seen in 87.42% cases with mean duration of 2.42 years. Menstrual dysfunctions, abdominal or pelvic pain and lump were seen in 38.92%, 14.37% and 10.77% cases. Abnormal vaginal discharge and adnexal mass were seen in 28.14% and 13.17 % cases. On diagnostic laparoscopy, definite findings of tuberculosis (beaded tubes, tuebrcles and caseous nodules) were seen in 96 (57.48%) women while probable findings of tuberculosis (pelvic or abdominal adhesions, hydrosaplinx, tubo-ovarian mass, pyosalpinx) were seen in 81 (48.50%) women. On laboratory investigations, positive AFB on microscopy or culture was seen in 2.99% casess, PCR was positive in 47.90% gene Xpert was positive in 18.56% cases while epitheloid granuloma was seen on histopathology in 16 (9.58%) cases. Gene Xpert had sensitivity of 35.63%, specificity of 100%, positive predictive value of 100% and negative predictive value of 58.82% and diagnostic accuracy of 66.47% in the present study.

CONCLUSION

Gene Xpert is a very useful test to rule in tuberculosis whereas when it is negative it is not a good test to rule out tuberculosis.

Diagnostic accuracy of the Xpert MTB/RIF assay for abdominal tuberculosis: a systematic review and meta-analysis

BACKGROUND

We performed a meta-analysis to determine diagnostic accuracy of Xpert MTB/RIF for diagnosis of abdominal (intestinal or peritoneal) tuberculosis (TB) in various tissues (intestinal, omental/peritoneal tissue or ascitic fluid).

METHODS

Electronic databases were searched for observational studies on use of Xpert MTB/RIF in ascitic fluid, peritoneal, or omental tissue for diagnosis of peritoneal and intestinal TB. We calculated the pooled sensitivity, specificity and diagnostic odds ratio of Xpert MTB/RIF for diagnosis of peritoneal TB in comparison to composite reference standard (CRS) and culture, and in comparison to CRS for intestinal TB.

RESULTS

Twenty-five observational studies were included. The pooled sensitivity and specificity as assessed with peritoneal culture from ascites as an Index test was 64% (95% Confidence Interval [C.I.] 49-76%) and 97% (95% C.I., 95-99%) respectively and with peritoneal CRS was 30% (95% C.I., 22-40%) and 100% (95% C.I., 98-100%) respectively. In the intestinal group, the pooled sensitivity and specificity of Xpert MTB/RIF was 23% (95% C.I., 16-32%) and 100% (95% C.I., 52-100%). The AUC of peritoneal culture and intestinal tissue was 0.935 and 0.499.

CONCLUSION

Xpert MTB/RIF has modest sensitivity for diagnosis of peritoneal and intestinal tuberculosis but has a good specificity.

PROSPERO REGISTRATION

CRD42020140545.

Utility of circulating cell-free Mycobacterium tuberculosis DNA for the improved diagnosis of abdominal tuberculosis

Abdominal tuberculosis (ATB) continues to pose a major diagnostic challenge for clinicians due to its nonspecific clinical presentation, variable anatomical location and lack of sensitive diagnostic tools. In spite of the development of several assays till date; no single test has proved to be adequate for ATB diagnosis. In this study, we for the first time report the detection of circulating cell-free Mycobacterium tuberculosis (M. tuberculosis) DNA (cfMTB-DNA) in ascitic fluid (AF) samples and its utility in ATB diagnosis. Sixty-five AF samples were included in the study and processed for liquid culture, cytological, biochemical and molecular assays. A composite reference standard (CRS) was formulated to categorize the patients into 'Definite ATB' (M. tuberculosis culture positive, n = 2), 'Probable ATB' (n = 16), 'Possible ATB' (n = 13) and 'Non-TB' category (n = 34). Two molecular assays were performed, namely, the novel cfMTB-DNA qPCR assay targeting M. tuberculosis devR gene and Xpert MTB/RIF assay (Xpert), and their diagnostic accuracy was assessed using CRS as reference standard. Clinical features such as fever, loss of weight, abdominal distension and positive Mantoux were found to be strongly associated with ATB disease (p<0.05). cfMTB-DNA qPCR had a sensitivity of 66.7% (95% CI:40.9,86.7) with 97.1% specificity (95% CI:84.7,99.9) in 'Definite ATB' and 'Probable ATB' group collectively. The sensitivity increased to 70.9% (95% CI:51.9,85.8) in the combined 'Definite', 'Probable' and 'Possible' ATB group with similar specificity. The cfMTB-DNA qPCR assay performed significantly better than the Xpert assay which demonstrated a poor sensitivity of ≤16.7% with 100% (95% CI:89.7,100) specificity (p<0.001). We conclude that cfMTB-DNA qPCR assay is an accurate molecular test that can provide direct evidence of M. tuberculosis etiology and has promise to pave the way for improving ATB diagnosis.

Clinical validation of urine-based Xpert® MTB/RIF assay for the diagnosis of urogenital tuberculosis: A systematic review and meta-analysis

OBJECTIVES

Effective methods for diagnosing urogenital tuberculosis (UGTB) are important for its clinical management. Therefore, we undertook a systematic review to assess the performance of the urine-based Xpert MTB/RIF assay for UGTB.

METHODS

PubMed, Embase, Web of Science, the Cochrane library, and Scopus were systematically searched up to July 30, 2019. A hierarchical summary receiver operating characteristic (HSROC) was applied to calculate the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and odds ratio (OR) for the diagnostic accuracy of the Xpert test.

RESULTS

Our search identified 858 unique articles from which 69 studies were selected for full-text revision, with 12 studies meeting the inclusion criteria. Eleven studies comprising 1202 samples compared Xpert with mycobacterial culture, while 924 samples from eight studies compared it with a composite reference standard (CRS). The values for pooled sensitivity, specificity, PLR, NLR, and OR were 0.89, 0.95, 20.1, 0.18, and 159.53, respectively, when compared with the mycobacterial culture. Likewise, when compared with a CRS, the respective pooled sensitivity, specificity, PLR, NLR, and OR values were 0.55, 0.99, 40.67, 0.43, and 166.17, thereby suggesting a high level of accuracy for diagnosing UGTB. A meta-regression and sub-group analysis of TB-burden countries, study design, decontamination, concentration, and reference standard could not explain the heterogeneity (p > 0.05) in the diagnostic efficiency.

CONCLUSIONS

Our results suggested that Xpert is a promising diagnostic tool for the diagnosis of UGTB via urine specimen.

Diagnosing peritoneal tuberculosis

Peritoneal tuberculosis (TB) is one of the most challenging forms of extrapulmonary tuberculosis to diagnose. This challenge can be compounded in low incidence regions, and in patients with cirrhosis in whom the presence of ascites alone may not prompt further investigation. A delay in the diagnosis and treatment of peritoneal tuberculosis may lead to worse clinical outcomes. This case describes a 64-year-old Italian male with decompensated cirrhosis being evaluated for liver transplantation, who developed abdominal pain and a persistent inflammatory ascites with peritoneal thickening despite antibiotic therapy. Peritoneal tuberculosis was suspected, although non-invasive and invasive direct mycobacterial testing remained negative. A constellation of positive QuantiFERON-TB Gold In-Tube test, elevated ascitic adenosine deaminase and dramatic symptomatic and radiographic response to empiric anti-tuberculous therapy confirmed the diagnosis of peritoneal tuberculosis. This paper will review the approach to the diagnosis of peritoneal tuberculosis.

Female genital tuberculosis: Revisited

Female genital tuberculosis (FGTB) is caused by Mycobacterium tuberculosis (rarely Mycobacterium bovis and/or atypical mycobacteria) being usually secondary to TB of the lungs or other organs with infection reaching through haematogenous, lymphatic route or direct spread from abdominal TB. In FGTB, fallopian tubes are affected in 90 per cent women, whereas uterine endometrium is affected in 70 per cent and ovaries in about 25 per cent women. It causes menstrual dysfunction and infertility through the damage of genital organs. Some cases may be asymptomatic. Diagnosis is often made from proper history taking, meticulous clinical examination and judicious use of investigations, especially endometrial aspirate (or biopsy) and endoscopy. Treatment is through multi-drug antitubercular treatment for adequate time period (rifampicin, isoniazid, pyrazinamide, ethambutol daily for 60 days followed by rifampicin, isoniazid, ethambutol daily for 120 days). Treatment is given for 18-24 months using the second-line drugs for drug-resistant (DR) cases. With the advent of increased access to rapid diagnostics and newer drugs, the management protocol is moving towards achieving universal drug sensitivity testing and treatment with injection-free regimens containing newer drugs, especially for new and previously treated DR cases.

Diagnostic accuracy of Xpert MTB/RIF assay in extrapulmonary tuberculosis

Introduction

The WHO endorsed Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, has been evaluated for pulmonary TB in a number of studies but very few have investigated it for extrapulmonary specimens. The present study evaluates the performance of Xpert MTB/RIF assay in the diagnosis of extrapulmonary TB (EPTB).

Aim and Objectives

The aim of the study is to determine sensitivity and specificity of Xpert MTB/RIF assay for diagnosis of EPTB and RIF resistance in comparison to culture on Lowenstein-Jensen (LJ) medium and proportion method (PM), respectively.

Materials and Methods

A total of 738 specimens from clinically suspected cases of EPTB were subjected to Ziehl-Neelsen staining, Xpert MTB/RIF assay and culture on LJ medium. PM was done on MTB isolates.

Results

The sensitivity, specificity of Xpert MTB/RIF assay for diagnosis of EPTB were 84.91% (95% confidence interval [CI] 72.41%-93.25%) and 86.72% (95% CI 83.94%-89.17%) and for RIF resistance detection were 60.00% (95% CI 32.29%-83.66%) and 94.74% (95% CI 73.97%-99.87%), respectively. Among culture-positive cases, the sensitivity of Xpert MTB/RIF assay was 94.12% in smear positive and 80.56% in smear-negative cases. Xpert MTB/RIF showed maximum sensitivity of MTB detection from lymph node specimens (100% [95% CI 54.07%-100.00%]) and other body fluids (100% [95% CI 15.81%-100.00%]).

Conclusion

The present study establishes Xpert MTB/RIF assay as a promising tool in the rapid diagnosis of EPTB and detection of RIF resistance.

Curious case of fever of unknown origin

A 58-year-old immunocompetent woman presented with fever and significant weight loss of 4-month duration. She had mild pallor; rest of the examination was unremarkable. Investigations revealed anaemia with raised inflammatory markers. Cultures, serologies, routine urine examination, bone marrow examination, contrast enhanced CT and two-dimensional echocardiography examination were unremarkable. An 18F-fluorodeoxyglucose positron emission tomography with CT (18F-FDG-PET/CT) scan was performed which revealed atypical heterogenous uptake in bilateral renal cortex. Subsequently, urine GeneXpert came positive for Mycobacterium tuberculosis with sensitivity to rifampicin. She responded to category 1 antitubercular therapy. The challenges in diagnosis of genitourinary tuberculosis, low sensitivity of conventional diagnostic tests and potential role of GeneXpert and 18F-FDG-PET/CT scan are discussed in this report.

Xpert® MTB/RIF assay for extrapulmonary tuberculosis and rifampicin resistance

BACKGROUND

Tuberculosis (TB) is the world's leading infectious cause of death. Extrapulmonary TB accounts for 15% of TB cases, but the proportion is increasing, and over half a million people were newly diagnosed with rifampicin-resistant TB in 2016. Xpert^® MTB/RIF (Xpert) is a World Health Organization (WHO)-recommended, rapid, automated, nucleic acid amplification assay that is used widely for simultaneous detection of Mycobacterium tuberculosis complex and rifampicin resistance in sputum specimens. This Cochrane Review assessed the accuracy of Xpert in extrapulmonary specimens.

OBJECTIVES

To determine the diagnostic accuracy of Xpert a) for extrapulmonary TB by site of disease in people presumed to have extrapulmonary TB; and b) for rifampicin resistance in people presumed to have extrapulmonary TB.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, Latin American Caribbean Health Sciences Literature (LILACS), Scopus, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, the International Standard Randomized Controlled Trial Number (ISRCTN) Registry, and ProQuest up to 7 August 2017 without language restriction.

SELECTION CRITERIA

We included diagnostic accuracy studies of Xpert in people presumed to have extrapulmonary TB. We included TB meningitis and pleural, lymph node, bone or joint, genitourinary, peritoneal, pericardial, and disseminated TB. We used culture as the reference standard. For pleural TB, we also included a composite reference standard, which defined a positive result as the presence of granulomatous inflammation or a positive culture result. For rifampicin resistance, we used culture-based drug susceptibility testing or MTBDRplus as the reference standard.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, assessed risk of bias and applicability using the QUADAS-2 tool. We determined pooled predicted sensitivity and specificity for TB, grouped by type of extrapulmonary specimen, and for rifampicin resistance. For TB detection, we used a bivariate random-effects model. Recognizing that use of culture may lead to misclassification of cases of extrapulmonary TB as 'not TB' owing to the paucibacillary nature of the disease, we adjusted accuracy estimates by applying a latent class meta-analysis model. For rifampicin resistance detection, we performed univariate meta-analyses for sensitivity and specificity separately to include studies in which no rifampicin resistance was detected. We used theoretical populations with an assumed prevalence to provide illustrative numbers of patients with false positive and false negative results.

MAIN RESULTS

We included 66 unique studies that evaluated 16,213 specimens for detection of extrapulmonary TB and rifampicin resistance. We identified only one study that evaluated the newest test version, Xpert MTB/RIF Ultra (Ultra), for TB meningitis. Fifty studies (76%) took place in low- or middle-income countries. Risk of bias was low for patient selection, index test, and flow and timing domains and was high or unclear for the reference standard domain (most of these studies decontaminated sterile specimens before culture inoculation). Regarding applicability, in the patient selection domain, we scored high or unclear concern for most studies because either patients were evaluated exclusively as inpatients at tertiary care centres, or we were not sure about the clinical settings.Pooled Xpert sensitivity (defined by culture) varied across different types of specimens (31% in pleural tissue to 97% in bone or joint fluid); Xpert sensitivity was > 80% in urine and bone or joint fluid and tissue. Pooled Xpert specificity (defined by culture) varied less than sensitivity (82% in bone or joint tissue to 99% in pleural fluid and urine). Xpert specificity was ≥ 98% in cerebrospinal fluid, pleural fluid, urine, and peritoneal fluid.Xpert testing in cerebrospinal fluidXpert pooled sensitivity and specificity (95% credible interval (CrI)) against culture were 71.1% (60.9% to 80.4%) and 98.0% (97.0% to 98.8%), respectively (29 studies, 3774 specimens; moderate-certainty evidence).For a population of 1000 people where 100 have TB meningitis on culture, 89 would be Xpert-positive: of these, 18 (20%) would not have TB (false-positives); and 911 would be Xpert-negative: of these, 29 (3%) would have TB (false-negatives).For TB meningitis, ultra sensitivity and specificity against culture (95% confidence interval (CI)) were 90% (55% to 100%) and 90% (83% to 95%), respectively (one study, 129 participants).Xpert testing in pleural fluidXpert pooled sensitivity and specificity (95% CrI) against culture were 50.9% (39.7% to 62.8%) and 99.2% (98.2% to 99.7%), respectively (27 studies, 4006 specimens; low-certainty evidence).For a population of 1000 people where 150 have pleural TB on culture, 83 would be Xpert-positive: of these, seven (8%) would not have TB (false-positives); and 917 would be Xpert-negative: of these, 74 (8%) would have TB (false-negatives).Xpert testing in urineXpert pooled sensitivity and specificity (95% CrI) against culture were 82.7% (69.6% to 91.1%) and 98.7% (94.8% to 99.7%), respectively (13 studies, 1199 specimens; moderate-certainty evidence).For a population of 1000 people where 70 have genitourinary TB on culture, 70 would be Xpert-positive: of these, 12 (17%) would not have TB (false-positives); and 930 would be Xpert-negative: of these, 12 (1%) would have TB (false-negatives).Xpert testing for rifampicin resistanceXpert pooled sensitivity (20 studies, 148 specimens) and specificity (39 studies, 1088 specimens) were 95.0% (89.7% to 97.9%) and 98.7% (97.8% to 99.4%), respectively (high-certainty evidence).For a population of 1000 people where 120 have rifampicin-resistant TB, 125 would be positive for rifampicin-resistant TB: of these, 11 (9%) would not have rifampicin resistance (false-positives); and 875 would be negative for rifampicin-resistant TB: of these, 6 (1%) would have rifampicin resistance (false-negatives).For lymph node TB, the accuracy of culture, the reference standard used, presented a greater concern for bias than in other forms of extrapulmonary TB.

AUTHORS' CONCLUSIONS

In people presumed to have extrapulmonary TB, Xpert may be helpful in confirming the diagnosis. Xpert sensitivity varies across different extrapulmonary specimens, while for most specimens, specificity is high, the test rarely yielding a positive result for people without TB (defined by culture). Xpert is accurate for detection of rifampicin resistance. For people with presumed TB meningitis, treatment should be based on clinical judgement, and not withheld solely on an Xpert result, as is common practice when culture results are negative.

Recurrent chylous effusions and venous thrombosis: Uncommon presentation of a common condition

Spontaneous bilateral chylothorax and chylous ascites rarely develop in conjunction with systemic venous thrombosis, and the most common cause of non-traumatic chylous effusion is a malignancy. A 23-year-old immunocompetent female presented with a fever of 5 months' duration associated with progressive shortness of breath and abdominal distension. Evaluation revealed bilateral chylothorax, chylous ascites, and multiple venous thrombosis. Anti-tubercular drugs were initiated on the basis of a lymph node biopsy and computed tomography findings, but her symptoms worsened, and she developed massive bilateral pleural effusions with type 2 respiratory failure requiring invasive mechanical ventilation. She was managed with anti-tubercular drugs, chest tube drainage, octreotide, anticoagulants, and other supportive treatments. A multipronged approach to the management of chylous effusions and addition of octreotide led to resolution of symptoms. The challenges faced in diagnosing and managing this case are discussed in this report.

Is Xpert MTB/RIF appropriate for diagnosing tuberculous pleurisy with pleural fluid samples? A systematic review

Background

Tuberculous pleurisy (TP) presents a diagnostic problem due to the limitations of traditional diagnostic methods. Different studies with the Xpert MTB/RIF assay have drawn variable conclusions about its values in TP diagnosis. We conducted a meta-analysis to assess whether the Xpert MTB/RIF assay is appropriate for the diagnosis of TP using pleural fluid samples.

Methods

A systematic search of four literature databases in English and Chinese language was performed to identify studies involving the use of Xpert MTB/RIF in patients with TP confirmed by plural biopsy and/or mycobacterial culture. Pooled sensitivity, specificity and accordance proportion were calculated, and the forest plots were generated to assess the accuracy of Xpert MTB/RIF for TP diagnosis.

Results

We identified 23 studies meeting our inclusion criteria. The pooled sensitivity and specificity of Xpert MTB/RIF were 30% (95% CI: 21–42%, I² = 87.93%) and 99% (95% CI: 97–100%, I² = 96.20%), respectively, and the area under the SROC curve (AUC) of Xpert MTB/RIF was 0.86 (95% CI: 0.83–0.89). Compared with drug susceptibility testing (DST), the pooled accordance rate of Xpert MTB/RIF in detecting rifampicin-susceptible cases and rifampicin-resistant cases was 99% (95% CI: 95–104%, I² = 8.7%) and 94% (95% CI: 86–102%), respectively.

Conclusions

Our analysis suggests that the Xpert MTB/RIF assay is of limited value as a screening test for TP but has a high potential for confirming TP diagnosis and differentiating TP from non-TB diseases using pleural fluid samples.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3196-4) contains supplementary material, which is available to authorized users.

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

Pleural tuberculosis (pTB) is a grave form of extrapulmonary tuberculosis. Microbiological tests are usually found to be inadequate for pTB diagnosis. The absence of a uniform 'composite reference standard' is challenging; therefore, diagnosis is usually performed using a combination of diversified criteria. Nucleic acid tests vary in diagnostic accuracy and have not yet been integrated into clinical decision making. This review assesses the varied criteria used for pTB classification and the challenges afflicting pleural fluid-based DNA diagnostic tests, namely, PCR and Xpert^® MTB/RIF. In the 58 studies (PCR: n = 33; Xpert: n = 25) analyzed, reference standards were heterogeneous and PCR/Xpert pooled sensitivity values (range: 0-100%) were inadequate. However, the consistent high specificity of Xpert (range: 90-100%) indicated its utility as a 'rule-in' test. There is an urgent need to evaluate existing and new molecular tests in well-designed studies  to accurately assess their utility for pTB diagnosis. To conclude, rapid and accurate tests are warranted for pTB diagnosis.

Evaluation of Xpert MTB/RIF assay performance in the diagnosis of abdominal tuberculosis

Background/Aims

The use of genetic probes for the diagnosis of pulmonary tuberculosis (TB) has been well described. However, the role of these assays in the diagnosis of intestinal tuberculosis is unclear. We therefore assessed the diagnostic utility of the Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, and estimated the prevalence of multidrug-resistant (MDR) TB in the Indian population.

Methods

Of 99 patients recruited, 37 had intestinal TB; two control groups comprised 43 with Crohn's disease (CD) and 19 with irritable bowel syndrome. Colonoscopy was performed before starting any therapy; mucosal biopsies were subjected to histopathology, acid-fast bacilli staining, Lowenstein-Jensen culture, and nucleic acid amplification testing using the Xpert MTB/RIF assay. Patients were followed up for 6 months to confirm the diagnosis and response to therapy. A composite reference standard was used for diagnosis of TB and assessment of the diagnostic utility of the Xpert MTB/RIF assay.

Results

Of 37 intestinal TB patients, the Xpert MTB/RIF assay was positive in three of 37 (8.1%), but none had MDR-TB. The sensitivity, specificity, positive predictive value, and negative predictive value of the Xpert MTB/RIF assay was 8.1%, 100%, 100%, and, 64.2%, respectively.

Conclusions

The Xpert MTB/RIF assay has low sensitivity but high specificity for intestinal TB, and may be helpful in endemic tuberculosis areas, when clinicians are faced with difficulty differentiating TB and CD. Based on the Xpert MTB/RIF assay, the prevalence of intestinal MDR-TB is low in the Indian population.

[Performance of GeneXpert MTB / RIF® in the diagnosis of extrapulmonary tuberculosis in Dakar: 2010-2015]

Introduction

Le défi des pays en voie de développement est la disponibilité de méthodes de diagnostic rapide et précis pour le management de la tuberculose. Des techniques moléculaires offrent cet avantage et nous avons utilisé le test GeneXpert MTB/RIF dans le diagnostic de la tuberculose extra-pulmonaire pour évaluer sa performance par rapport aux méthodes conventionnelles.

Méthodes

Entre 2010 et 2015, 544 échantillons cliniques extra-pulmonaires ont été recueillis et traitées par la microscopie, la culture et le GeneXpert. L'étude de la sensibilité aux antituberculeux a été effectué avec le MGIT 960. Le Génotype MTBDRplus a été utilisé pour confirmer les cas de résistance à la rifampicine détectés par le système GX.

Résultats

La population d'étude de 544 patients incluait 55,15% d'hommes et 44,85% de femmes. L'âge des patients variait entre 1 à 92 avec la majorité dans le groupe d'âge 18-45 ans. La sensibilité et la spécificité globale de la microscopie étaient de 43,86% et 98,36%, et pour le GeneXpert^® 94,74% et 97,95% respectivement avec 95% IC. Deux résultats de résistance à la rifampicine discordants ont été trouvées entre le test GeneXpert et la méthode phénotypique. Les résultats du test MTBDRplus ont montré une concordance de 100% avec ceux du MGIT 960 pour les cas discordants de résistance à la rifampicine.

Conclusion

Cette étude a montré que le test GeneXpert a une plus grande sensibilité pour le diagnostic de routine de la tuberculose extra-pulmonaire et devrait être utilisé à la place de la microscopie. Les cas de résistance à la rifampicine détectés par le GeneXpert doivent être confirmés par d'autres tests moléculaires avant d'initier un traitement.

Miliary tuberculosis: A new look at an old foe

Miliary tuberculosis (TB), is a fatal form of disseminated TB characterized by tiny tubercles evident on gross pathology similar to innumerable millet seeds in size and appearance. Global HIV/AIDS pandemic and increasing use of immunosuppressive drugs have altered the epidemiology of miliary TB. Keeping in mind its protean manifestations, clinicians should have a low threshold for suspecting miliary TB. Careful physical examination should focus on identifying organ system involvement early, particularly TB meningitis, as this has therapeutic significance. Fundus examination for detecting choroid tubercles can help in early diagnosis as their presence is pathognomonic of miliary TB. Imaging modalities help in recognizing the miliary pattern, define the extent of organ system involvement and facilitate image guided fine-needle aspiration cytology or biopsy from various organ sites. Sputum or BAL fluid examination, pleural, pericardial, peritoneal fluid and cerebrospinal fluid studies, fine needle aspiration cytology or biopsy of the lymph nodes, needle biopsy of the liver, bone marrow aspiration and biopsy, testing of body fluids must be carried out. GeneXpert MTB/RIF, line probe assay, mycobacterial culture and drug-susceptibility testing must be carried out as appropriate and feasible. Treatment of miliary TB should be started at the earliest as this can be life saving. Response to first-line anti-TB drugs is good. Screening and monitoring for complications like acute respiratory distress syndrome (ARDS), adverse drug reactions like drug-induced liver injury, drug-drug interactions, especially in patients co-infected with HIV/AIDS, are warranted. Sparse data are available from randomized controlled trials regarding optimum regimen and duration of anti-TB treatment.

Diagnostic Performance of Xpert MTB/RIF in Tuberculous Pleural Effusion: Systematic Review and Meta-analysis

A systematic review investigating the role of Xpert MTB/RIF in the diagnosis of tuberculous pleural effusion (TPE) was conducted. The pooled sensitivities and specificities of Xpert MTB/RIF were 51.4% and 98.6%, respectively, with culture used as a reference standard and 22.7% and 99.8%, respectively, with a composite reference standard (CRS) used as the benchmark. Xpert MTB/RIF has low sensitivity but excellent specificity in the diagnosis of TPE.

Evaluating the Diagnostic Accuracy of Xpert MTB/RIF Assay in Pulmonary Tuberculosis

Pulmonary tuberculosis still remains a major communicable disease worldwide. In 2013, 9 million people developed TB and 1.5 million people died from the disease. India constitutes 24% of the total TB burden. Early detection of TB cases is the key to successful treatment and reduction of disease transmission. Xpert MTB/RIF, an automated cartridge-based molecular technique detects Mycobacterium tuberculosis and rifampicin resistance within two hours has been endorsed by WHO for rapid diagnosis of TB. Our study is the first study from India with a large sample size to evaluate the performance of Xpert MTB/RIF assay in PTB samples. The test showed an overall sensitivity and specificity of 95.7% (430/449) and 99.3% (984/990) respectively. In smear negative-culture positive cases, the test had a sensitivity of 77.7%. The sensitivity and specificity for detecting rifampicin resistance was 94.5% and 97.7% respectively with respect to culture as reference standard. However, after resolving the discrepant samples with gene sequencing, the sensitivity and specificity rose to 99.0% and 99.3% respectively. Hence, while solid culture still forms the foundation of TB diagnosis, Xpert MTB/RIF proposes to be a strong first line diagnostic tool for pulmonary TB cases.

Tissue Xpert™ MTB/Rif assay is of limited use in diagnosing peritoneal tuberculosis in patients with exudative ascites

BACKGROUND

Xpert™ MTB/Rif is a multiplex hemi-nested real-time PCR-based assay to detect presence of M. tuberculosis within 2 hours of sample collection. The present study aimed at assessing efficacy of Xpert™ MTB/Rif assay for diagnosing peritoneal tuberculosis.

METHODS

Patients with exudative ascites, fluid negative for acid-fast bacilli on auramine O fluorescence staining and unyielding fluid cytology for malignant cells, were included. Ultrasound-guided omental biopsy samples were obtained in all. Xpert™ MTB/Rif assay on tissue samples was assessed against a composite "reference" standard for diagnosis of peritoneal tuberculosis, defined as presence of any of the three-culture showing M tuberculosis, granulomatous inflammation on histology or resolution of ascites with 2 months of antitubercular therapy.

RESULTS

During January 2012-July 2013, 28 patients (age:43 ± 15 years; mean ± SD; male:20) were recruited. Serum ascitic albumin gradient was <1.1 in all except in four patients with underlying cirrhosis. Twenty-one of the 28 patients had peritoneal TB as diagnosed by composite reference standard (histology:18; culture:4; treatment response:3). Seven patients (25%) had an alternative diagnosis (metastatic carcinoma 2, adenocarcinoma 2, mesothelioma 2, and systemic lupus erythematous 1). Xpert™ MTB/Rif assay was positive in 4/21 patients with peritoneal tuberculosis and in none of the 7 patients with alternative diagnosis. Thus, sensitivity, specificity, positive, and negative predictive values for tissue Xpert™ MTB/Rif assay in diagnosing peritoneal tuberculosis were 19% (95% C.I: 6% to 42%), 100% (95% C.I: 59% to 100%), 100% (40% to 100%), and 29% (95% C.I: 13% to 51%), respectively.

INTERPRETATION AND CONCLUSION

Tissue Xpert™ MTB/Rif assay was of limited use in diagnosing peritoneal tuberculosis.