Interferon-gamma release assay as a diagnostic test for tuberculosis-associated uveitis

Ocular manifestations and diagnosis of tuberculosis involving the uvea: a case series

BACKGROUND

Ocular tuberculosis (TB) affects 1-2% of patients with TB, with TB uveitis being the most common. This series aims to look at different manifestations of tuberculosis associated uveitis and the different tests used to make a presumptive or definitive diagnosis.

METHODS

Patients diagnosed with TB related uveitis in Hong Kong SAR between 2017 and 2020 were reviewed. Demographics, clinical features, investigations and treatments of patients were collected.

RESULTS

Fifteen eyes in 10 patients with a mean age 57.30 ± 10.17 years were included. The ocular manifestations on presentation included anterior uveitis (50%), posterior uveitis (40%) and panuveitis (10%), where 70% of them were unilateral and 30% were bilaterally infected; on subsequent visits the manifestations further developed into posterior uveitis (40%), panuveitis (40%) and anterior uveitis (20%), where 50% of them were unilateral and 50% bilateral infected. Tuberculosis tests were positive in 5 out of 7 Mantoux tests, 4 out of 4 T-SPOT TB tests, 3 out of 4 QuantiFERON-TB gold tests, 1 out of 1 lymph node biopsy, 0 out of 9 chest x-rays, and no aqueous fluid polymerase chain reaction (PCR) was tested. Vision impairing complications were seen in 6 patients where retinal vasculitis was most commonly seen. With anti-TB treatment prescribed in 9 patients, side effects occurred in 5 patients, including ocular hypertension, disc swelling, and hepatitis.

CONCLUSIONS

Ocular TB infections may manifest in various forms, and can involve different parts of the eye. Bilateral involvement of TB is commonly presented, and both eyes should be evaluated at every follow up. When TB is suspected in a patient, diagnostic confirmation requires multimodal investigations where a negative chest x-ray is not useful in ruling out ocular TB infections, especially in an endemic region like Hong Kong. In these patients, it is crucial to have a high index of suspicion for TB, even when they do not demonstrate classical respiratory signs and symptoms of TB.

Role of Interferon-Gamma Release Assay for the Diagnosis and Clinical Follow up in Ocular Tuberculosis

PURPOSE

To assess the performance of interferon-gamma release assay (IGRA) associated with tuberculosis skin test (TST) for ocular tuberculosis (OTB) diagnosis and therapeutic decision making.

METHOD

One hundred and ninety-one patients with ocular inflammation were prospectively followed-up. Patients with clinical signs highly suspected of OTB, TST≥10 mm, and/or IGRA≥0.35 IU/mL received antitubercular therapy (ATT). Sensitivity (Se), specificity (Sp), and area under the curve (AUC) were assessed.

RESULTS

Seventy-two (37.7%) patients received ATT for presumed OTB. Combining TST and IGRA had Se=89.6%, Sp=99.2%, and AUC (0.98) significantly higher compared to TST (0.85, Z=6.3, p<.001) or IGRA (0.95, Z=2.5, p=.01). Prior history of corticosteroids or immunosuppressant with concomitantly oral prednisone and baseline IGRA> 2.0 IU/mL was associated significantly with more recurrences in ATT patients (p=.01)      .

CONCLUSION

Considering TST and IGRA together was more effective in assessing OTB diagnosis. The real value of the IGRA test to predict recurrences needs further studies.

Diagnosis and biomarkers for ocular tuberculosis: From the present into the future

Tuberculosis is an airborne disease caused by Mycobacterium tuberculosis (Mtb) and can manifest both pulmonary and extrapulmonary disease, including ocular tuberculosis (OTB). Accurate diagnosis and swift optimal treatment initiation for OTB is faced by many challenges combined with the lack of standardized treatment regimens this results in uncertain OTB outcomes. The purpose of this study is to summarize existing diagnostic approaches and recently discovered biomarkers that may contribute to establishing OTB diagnosis, choice of anti-tubercular therapy (ATT) regimen, and treatment monitoring. The keywords ocular tuberculosis, tuberculosis, Mycobacterium, biomarkers, molecular diagnosis, multi-omics, proteomics, genomics, transcriptomics, metabolomics, T-lymphocytes profiling were searched on PubMed and MEDLINE databases. Articles and books published with at least one of the keywords were included and screened for relevance. There was no time limit for study inclusion. More emphasis was placed on recent publications that contributed new information about the pathogenesis, diagnosis, or treatment of OTB. We excluded abstracts and articles that were not written in the English language. References cited within the identified articles were used to further supplement the search. We found 10 studies evaluating the sensitivity and specificity of interferon-gamma release assay (IGRA), and 6 studies evaluating that of tuberculin skin test (TST) in OTB patients. IGRA (Sp = 71-100%, Se = 36-100%) achieves overall better sensitivity and specificity than TST (Sp = 51.1-85.7%; Se = 70.9-98.5%). For nuclear acid amplification tests (NAAT), we found 7 studies on uniplex polymerase chain reaction (PCR) with different Mtb targets, 7 studies on DNA-based multiplex PCR, 1 study on mRNA-based multiplex PCR, 4 studies on loop-mediated isothermal amplification (LAMP) assay with different Mtb targets, 3 studies on GeneXpert assay, 1 study on GeneXpert Ultra assay and 1 study for MTBDRplus assay for OTB. Specificity is overall improved but sensitivity is highly variable for NAATs (excluding uniplex PCR, Sp = 50-100%; Se = 10.5-98%) as compared to IGRA. We also found 3 transcriptomic studies, 6 proteomic studies, 2 studies on stimulation assays, 1 study on intraocular protein analysis and 1 study on T-lymphocyte profiling in OTB patients. All except 1 study evaluated novel, previously undiscovered biomarkers. Only 1 study has been externally validated by a large independent cohort. Future theranostic marker discovery by a multi-omics approach is essential to deepen pathophysiological understanding of OTB. Combined these might result in swift, optimal and personalized treatment regimens to modulate the heterogeneous mechanisms of OTB. Eventually, these studies could improve the current cumbersome diagnosis and management of OTB.

An excursion into ocular tuberculosis

Till today, ocular tuberculosis (OTB) presents clinicians with significant challenges in diagnosis and management. There is no one-size-fits-all approach to a heterogeneous disease like OTB, and clinicians often have to consider a multitude of factors when initiating treatment, such as tuberculosis endemicity, the probability of a true OTB diagnosis in the setting of nonspecific ocular features, the effective duration of treatment, and the likelihood of vision-threatening complications in the patient. It is no wonder that treatment protocols are widely varied globally. There have been recent developments in the standardization of nomenclature and therapeutic strategies for OTB, as established by the Collaborative OTB Study Working Group. In this review, we referred to findings in retrospective studies, international clinical guidelines, and OTB consortiums, to explore the clinical presentations, investigations, and updated management principles for patients with presumed tubercular uveitis.

Interferon-gamma release assays in tuberculous uveitis: a comprehensive review

Tuberculous uveitis (TBU) comprises a broad clinical spectrum of ocular manifestations, making its diagnosis challenging. Ophthalmologists usually require evidence from investigations to confirm or support a clinical diagnosis of TBU. Since direct isolation of the causative organism from ocular specimens has limitations owing to the small volume of the ocular specimens, resultant test positivities are low in yield. Immunodiagnostic tests, including the tuberculin skin test and interferon-gamma release assays (IGRAs), can help support a clinical diagnosis of TBU. Unlike the tuberculin skin test, IGRAs are in vitro tests that require a single visit and are not affected by prior Bacillus Calmette-Guerin vaccination. Currently, available IGRAs consist of different techniques and interpretation methods. Moreover, newer generations have been developed to improve the sensitivity and ability to detect active tuberculosis. This narrative review collates salient practice points as a reference for general ophthalmologists, such as evidence for the utilization of IGRAs in patients with suspected TBU, and summarizes basic knowledge and details of clinical applications of these tests in a clinical setting.

Ocular syphilis

Multiple studies around the world suggest that syphilis is re-emerging. Ocular syphilis - with a wide range of presentations, most of which are subtypes of uveitis - has become an increasingly common cause of ocular inflammation over the past 20 years. Its rising incidence, diagnostic complexity, and manifestations that have only recently been characterized make ocular syphilis relevant from the public health, clinical, and scientific perspectives. We review the demographics, epidemiology, clinical features, ocular imaging findings, diagnosis, and medical management of this condition.

Role of interferon gamma release assay in the diagnosis and management of Mycobacterium tuberculosis-associated uveitis: a review

Tuberculosis (TB)-associated uveitis is a common cause of infectious uveitis in the developing world. Diagnosis of TB uveitis remains a challenge. The role of interferon gamma release assays (IGRAs) is uncertain. Herein we summarise the available literature on the utility of IGRAs in the diagnosis and management of TB uveitis. We searched PubMed database from 1 August 2010 to 31 July 2020 using the following keywords alone and in combination: 'interferon-gamma release assay', 'QuantiFERON', 'T-SPOT.TB', 'TB uveitis', 'serpiginous like choroiditis', 'tuberculoma', 'TB vasculitis', 'TB panuveitis' and 'ocular tuberculosis'. Data from 58 relevant studies were collated. The review is focused on currently marketed versions of IGRA tests: QuantiFERON-TB Gold In-Tube assay, QuantiFERON-TB Gold Plus assay (QFT-Plus) and T-SPOT.TB. We found limited evidence regarding the diagnostic utility of IGRA in patients with uveitis. No study was identified evaluating the newer QFT test-the QFT-Plus-in patients with uveitis. Similarly, there is lack of data directly comparing QFT-Plus with T-SPOT.TB specifically for the diagnosis of TB uveitis.

Antimicrobial guide to posterior segment infections

PURPOSE

This review article is meant to serve as a reference guide and to assist the treating physician in making an appropriate selection and duration of an antimicrobial agent.

METHODS

Literature review.

RESULTS

Infections of the posterior segment require prompt medical or surgical therapy to reduce the risk of permanent vision loss. While numerous options exist to treat these infections, doses and alternative therapies, especially with contraindications for first-line therapy, are often elusive. Antimicrobial agents to treat posterior segment infections can be administered via various routes, including topical, intravitreal, intravenous, and oral.

CONCLUSIONS

Although there are many excellent review articles on the management of endophthalmitis, we take the opportunity in this review to comprehensively summarize the appropriate antimicrobial regimen of both common and rare infectious etiologies of the posterior segment, using evidence from clinical trials and large case series.

[Observational study of QuantiFERON® management for ocular tuberculosis diagnosis: Analysis of 244 consecutive tests]

INTRODUCTION

Ocular tuberculosis (TB) diagnosisremains difficult and quantiferon (QFT) contribution needs still yet to be specified, despite its generalization in France. The purpose of this observational study is to assess in which ocular inflammation (OI) presentation QFT is prescribed and to evaluate the added value of new QuantiFERON®-TB Gold Plus (QFT-Plus) test for diagnosis ocular TB diagnosis.

PATIENTS AND METHODS

Monocentric, observational study, carried out in an ophthalmology department over a period of 5 months. Inclusion criteria were defined as an existence of an OI for which a QFT-Plus test was part of the etiological investigations. Of the 316 consecutive files, 72 were excluded (indeterminate test, prescription before anti-TNFα or immunosuppressant initiation, missing data, wrong indication) and 244 were selected and divided into two groups: group one (anterior uveitis/episcleritis, n=129) and group two (intermediate/posterior uveitis/optic neuritis/ocular myositis, n=115). All positive QFT patients underwent an etiological investigation including thoracic imaging.

RESULTS

Forty-five patients, aged 52±12 years, had positive QFT (18.5%), including 18 patients for group 1 and 27 for group 2. Living in TB-endemic area, TB exposure and chest imaging abnormalities were identified in 70%, 27% and 22% of cases, respectively. OI was chronic in 36% of cases (group one, 4/18; group two, 12/27). None of the 18 patients, in group 1, received anti-tuberculosis treatment (ATT) or experienced a relapse during one-year follow-up. Four QFT+ patients, from group 2 (15%) had another associated disease explaining their uveitis. Among the 23 other patients without identified etiology, 13 had at least one relevant ophthalmological signs predictive of TB uveitis (posterior synechiae, retinal vasculitis and/or choroidal granuloma) (59%). Eleven patients received a 6-month ATT trial. Radiological abnormalities and granulomas at angiography were significantly more frequent among treated patients (p=0.03 and 0.001, respectively). A full OI recovery was observed for 8 patients (73%), considered ex-post as ocular TB. Nine patients in group 2 received rifampicin/isoniazid dual therapy for 3 months, but no conclusion could be drawn as to the benefit of such prescription on OI. QFT rate comparison, according to CD4 stimulation by ESAT-6/CFP-10 peptides or by CD4/CD8 co-stimulation, was comparable and found only 4 cases of discrepancy (1.6%). None of these 4 cases had ocular TB diagnosis.

CONCLUSION

Positive QFT frequency among patients consulting for posterior OI remains high. In this study, radiological abnormalities and granulomas at angiography seemed to be more closely related to clinician decision for starting ATT trial in QFT+ patients, which was effective in 73% of cases. QFT-Plus does not seem more relevant than QFT-TB in exploring an OI. Prospective studies are necessary to codify QFT management in the etiological assessment of OI and clearly define ATT trial indications as well as their modalities.

Collaborative Ocular Tuberculosis Study Consensus Guidelines on the Management of Tubercular Uveitis-Report 2: Guidelines for Initiating Antitubercular Therapy in Anterior Uveitis, Intermediate Uveitis, Panuveitis, and Retinal Vasculitis

TOPIC

The Collaborative Ocular Tuberculosis Study (COTS), supported by the International Ocular Inflammation Society, International Uveitis Study Group, and Foster Ocular Immunological Society, set up an international, expert-led consensus project to develop evidence- and experience-based guidelines for the management of tubercular uveitis (TBU).

CLINICAL RELEVANCE

The absence of international agreement on the use of antitubercular therapy (ATT) in patients with TBU contributes to a significant heterogeneity in the approach to the management of this condition.

METHODS

Consensus statements for the initiation of ATT in TBU were generated using a 2-step modified Delphi technique. In Delphi step 1, a smart web-based survey based on background evidence from published literature was prepared to collect the opinion of 81 international experts on the use of ATT in different clinical scenarios. The survey included 324 questions related to tubercular anterior uveitis (TAU), tubercular intermediate uveitis (TIU), tubercular panuveitis (TPU), and tubercular retinal vasculitis (TRV) administered by the experts, after which the COTS group met in November 2019 for a systematic and critical discussion of the statements in accordance with the second round of the modified Delphi process.

RESULTS

Forty-four consensus statements on the initiation of ATT in TAU, TIU, TPU, and TRV were obtained, based on ocular phenotypes suggestive of TBU and corroborative evidence of tuberculosis, provided by several combinations of immunologic and radiologic test results. Experts agreed on initiating ATT in recurrent TAU, TIU, TPU, and active TRV depending on the TB endemicity. In the presence of positive results for any 1 of the immunologic tests along with radiologic features suggestive of past evidence of tuberculosis infection. In patients with a first episode of TAU, consensus to initiate ATT was reached only if both immunologic and radiologic test results were positive.

DISCUSSION

The COTS consensus guidelines were generated based on the evidence from published literature, specialists' opinions, and logic construction to address the initiation of ATT in TBU. The guidelines also should inform public policy by adding specific types of TBU to the list of conditions that should be treated as tuberculosis.

Towards standardization of immune functional assays

Recent advances in the immunotherapy field require evaluation of the immune function to adapt therapeutic decisions. Immune functional assays (IFA) are able to reveal the immune status and would be useful to further adapt and/or improve patient's care. However, standardized methods are needed to implement IFA in clinical settings. We carried out an independent validation of a published method used to characterize the underlying host response to infectious conditions using an IFA. We evaluated the reproducibility and robustness of this IFA and the associated readout using an independent healthy volunteers (HV) cohort. Expression of a 44-gene signature and IFNγ protein secretion was assessed after stimulation. We observed a strong host-response correlation between the two cohorts. We also highlight that standardized methods for immune function evaluation exist and could be implemented in larger-scale studies. This IFA could be a relevant tool to reveal innate and adaptive immune dysfunction in immune-related disorders patients.

Clinical Profile and Treatment Response of Patients with Ocular Inflammation due to Presumed Ocular Tuberculosis: A Retrospective Study

Objectives:

Ocular tuberculosis is an extrapulmonary tuberculous infection and has varying manifestations which pose a huge challenge to diagnosis and treatment. The purpose of this study is to describe the various clinical manifestations of ocular inflammations due to tuberculosis and to assess the response to treatment following antituberculous therapy (ATT) and corticosteroids in these patients.

Materials and Methods:

We performed a retrospective analysis of 29 patients with presumed ocular tuberculosis who were started on ATT and completed follow-up of at least 6 months after ATT was initiated. The data collected were: age at presentation, sex, laterality, presence or absence of pulmonary/extrapulmonary tuberculosis, history of exposure to tuberculosis, site of ocular involvement and duration of illness, visual acuity at presentation and at 6-month follow-up, and response to treatment.

Results:

Most of the patients were of economically productive age, between 21-60 years. This most common presentation in our study population was unilateral nongranulomatous anterior uveitis. In spite of the delay between symptom onset and start of therapy, favorable response was noted in 79.3% of patients at completion of 6 months of ATT. The various reasons for the delay in start of therapy were also evaluated.

Conclusion:

In this case series, we presented the various ocular manifestations and the difficulties faced in the diagnosis of presumed ocular tuberculosis. Outcomes of ATT were favorable in most of our patients. Thus, the clinician should exercise a very high degree of suspicion and should not withhold a trial of ATT.

[Ocular tuberculosis]

Despite extensive investigations, including the use of Interferon-gamma release assays (IGRA), the diagnosis of intraocular tuberculosis (TB) remains challenging. Ocular evidence of Mycobacterium tuberculosis in low endemic countries for TB is extremely rare, leading mostly to a TB-related ocular inflammation presumptive diagnosis. This present work aims: to highlights the main clinical patterns suggestive of ocular TB; and the latest recommended guidelines for diagnosing ocular TB to clarify interferon-gamma release assay (IGRA) contribution and accuracy to the management of intraocular TB and its diagnosis, in addition to other available diagnostic tools, such as tuberculin skin test, bacteriologic and histologic analysis from intra/extra ocular sample and radiographic investigations; to define the accuracy of these diagnostic tools according to the endemic TB prevalence; and finally to identify therapeutic strategies adapted to the main clinical presentations of ocular TB. Our review of the literature shows that management of suspected ocular TB differs significantly based on whether patients are from high or low TB prevalence countries since accuracy of chest X-ray, tuberculin skin test and IGRA is significantly different. Taking into account these discrepancies, distinct guidelines should be determined for managing patients with suspected ocular TB, taking into consideration home prevalence of TB-patients.

A retrospective cohort study of patients treated with anti-tuberculous therapy for presumed ocular tuberculosis

BACKGROUND

Uveitis involving the posterior segment is a significant and potentially blinding condition. The diagnosis and treatment of patients with uveitis associated with tuberculosis remains controversial, and commonly, patients are systemically well. Use of the interferon-gamma release assays has added to the controversy, as the significance of a positive test may be uncertain. We aim to report the outcomes of anti-tuberculous treatment in a cohort of patients treated in Birmingham, for presumed "ocular tuberculosis", based on clinical findings, systemic assessment and specific testing for tuberculosis.

RESULTS

We found that in our cohort of 41 patients treated between 2010 and 2014, the majority achieved disease-free remission, even in cases where anti-tuberculous treatment was delayed.

CONCLUSIONS

Despite controversy, this study strongly supports the use of anti-tuberculous therapy in such patients and highlights the need for formal prospective trials and treatment protocols.

Retina and the tubercle Bacillus: Four decades of our journey and current understanding

Tuberculosis continues to be a major pandemic with enormous public health implication. Involvement of ocular tissues in the form of tubercles, tuberculomas, panophthalmitis, and iris granulomas are well recognized as definitive manifestations of tuberculosis. For these lesions, confirmatory evidence is available in the form of demonstration of acid-fast Bacillus on Ziehl-Neelsen staining. For other retinochoroidal disorders such as central serous chorioretinopathy, retinal vasculitis, and presumed ocular tuberculosis, hard evidence about the role of Mycobacterium tuberculosis is lacking. In this review, work done at our center over the past four decades in the form of experimental animal studies, nucleic acid amplification assays and clinical studies regarding the above retinochoroidal pathologies and the tubercle Bacillus is presented. It is possible that revisiting experimental animal studies may be a way forward in the current scenario of ambiguity about the cause-effect relationship between M. tuberculosis and few of the retinochoroidal disorders.

The Role of QuantiFERON®-TB Gold and Tuberculin Skin Test as Diagnostic Tests for Intraocular Tuberculosis in HIV-Positive and HIV-Negative Patients in South Africa

PURPOSE

To compare QuantiFERON®-TB Gold and tuberculin skin testing as diagnostic tests for intraocular tuberculosis in HIV positive and negative patients.

METHODS

A prospective study evaluating two different tests to help diagnose intraocular tuberculosis.

RESULTS

Thirty-five of 106 patients (33.0%) were diagnosed with intraocular tuberculosis including 11 (31.4%) with HIV infection. Patients were 6.95 times more likely to have intraocular tuberculosis if TST alone was positive (p < 0.001) versus 2.19 times more likely if Quantiferon alone was positive (p = 0.04). Tuberculin skin testing showed superior specificity (60.3% vs 33.3%) (p = 0.001) but similar sensitivity (90.3% vs 85.7%), positive (54.9% vs 40.5%) and negative predictive values (92.1% vs 81.5%) compared to Quantiferon. Specificity did not increase significantly if both skin testing and Quantiferon were positive.

CONCLUSIONS

In South Africa, with its high HIV burden and limited public health resources, Quantiferon testing should not replace tuberculin skin testing as it provides little additional diagnostic information.

Rare case of ocular tuberculosis in a diabetic patient: diagnostic and therapeutic dilemmas

We present the case of a patient who was diagnosed by chance with macular hypopyon during a conventional interdisciplinary examination. The clinical context and the association of a systemic disease, such as uncontrolled type 1 diabetes, rendered further investigations in this patient. Due to his immunocompromised status, etiology such as ocular fungi, lymphomas, tuberculosis was taken into account. Thorough complex investigations oriented the diagnosis towards ocular tuberculosis involvement.

Diagnosis of Ocular Tuberculosis

Ocular tuberculosis remains a presumptive clinical diagnosis, as the gold standard tests for diagnosing ocular tuberculosis are often not useful: Mycobacterium tuberculosis cultures require weeks to process on Lowenstein-Jenson media and have low yield from ocular samples; while acid-fast bacilli smears or polymerase chain reaction detection of M. tuberculosis DNA have low sensitivities. Thus, diagnosis is often based on suggestive clinical signs, which are supported by positive investigations: tuberculin skin test or interferon-gamma release assays; chest X-ray findings suggestive of pulmonary tuberculosis, and/or evidence of associated systemic tuberculosis infections in the absence of other underlying disease. The aim of this review is to provide an update on the methods of diagnosing ocular tuberculosis, and discuss the challenges of its diagnosis. We also suggest a step-ladder approach to a more accurate diagnosis of ocular tuberculosis by combining the available diagnostic tests.

Evaluation of the Accuracy of T-SPOT.TB for the Diagnosis of Ocular Tuberculosis in a BCG-vaccinated, Non-endemic Population

PURPOSE

To determine the performance of T-SPOT.TB, an interferon gamma release assay test, in patients with ocular tuberculosis (TB) in a BCG-vaccinated, non-endemic population.

METHODS

We employed a nested case-control design. In total, 45 subjects were enrolled (23 patients with ocular tuberculosis and 22 patients with other causes of uveitis). A blood sample was collected from each subject, and T-SPOT.TB was executed. Laboratory professionals were blinded to the disease status of each subject.

RESULTS

Five patients were excluded because of indeterminate results. The calculated sensitivity and specificity were 0.80 and 0.85, respectively. The positive likelihood ratio was 5.33 and the negative likelihood ratio was 0.23. The overall accuracy of the test was 0.83.

CONCLUSIONS

T-SPOT.TB adequately diagnosed ocular TB. This technique is particularly useful in populations where BCG vaccinations are still mandatory.

Ocular tuberculosis: current perspectives

The World Health Organization currently estimates that nearly two billion people, or one-third of the world’s population, are infected by tuberculosis, and that roughly 10% of the infected people are symptomatic. Tuberculosis affects the lungs in 80% of patients, while in the remaining 20% the disease may affect other organs, including the eye. Uveitis can be seen concurrently with tuberculosis, but a direct association is difficult to prove. Ocular tuberculosis is usually not associated with clinical evidence of pulmonary tuberculosis, as up to 60% of extrapulmonary tuberculosis patients may not have pulmonary disease. The diagnosis of tuberculous uveitis is often problematic and in nearly all reported cases, the diagnosis was only presumptive. Tuberculous uveitis is a great mimicker of various uveitis entities and it can be considered in the differential diagnosis of any type of intraocular inflammation. It is still unknown if ocular manifestations result from a direct mycobacterium infection or hypersensitivity reaction and this is reflected on the management of tuberculous uveitis. Prevalence of tuberculosis as an etiology of uveitis may reach up to 10% in endemic areas. Tuberculous uveitis is a vision-threatening disease that inevitably leads to blindness if not properly diagnosed and treated. The aim of this review is to illustrate the various clinical features and management of presumed tuberculous uveitis. The current review focuses on the diagnostic criteria, significance of tuberculin skin test, and use of systemic corticosteroids in the management of tuberculous uveitis as recommended in recent publications.

Multicenter clinical evaluation of three commercial reagent kits based on the interferon-gamma release assay for the rapid diagnosis of tuberculosis in China

OBJECTIVE

To evaluate the performance of three interferon-gamma release assay (IGRA) kits in detecting Mycobacterium tuberculosis infection in China.

METHODS

A multicenter clinical trial was used to compare the effectiveness and application of the three kits. A total of 1026 participants were enrolled at three hospitals, including 597 tuberculosis (TB) patients diagnosed clinically (517 patients with pulmonary TB and 80 patients with extrapulmonary TB) and 429 negative controls (244 patients with pulmonary disease but not TB, or with non-tuberculosis mycobacterial lung diseases, and 185 healthy people). Detection performance indicators including sensitivity, specificity, and the Youden index (YI) were used to evaluate performance.

RESULTS

Through bacterial culture evaluation, 224 of the 517 pulmonary TB patients were positive and all 429 negative controls were negative. When the gold standard bacterial methods were used, the sensitivity, specificity, and YI were 89.7% (201/224), 91.1% (391/429), and 0.81 for T-SPOT.TB, 86.2% (193/224), 87.2% (374/429), and 0.73 for QB-SPOT, and 83.9% (188/224), 88.6% (380/429), and 0.73 for TB-IGRA, respectively. There were no significant differences in the sensitivity and specificity of the three kits.

CONCLUSIONS

The results showed that the three kits had very high sensitivity and specificity and exhibited a good performance for the detection of M. tuberculosis infection.

Prospective head-to-head study comparing 2 commercial interferon gamma release assays for the diagnosis of tuberculous uveitis

PURPOSE

To perform a head-to-head comparison of 2 commercially available interferon-gamma release assays, QuantiFERON-TB Gold In-Tube (Cellestis, Chadstone, Victoria, Australia) and T-SPOT.TB (Oxford Immunotech, Abingdon, Oxfordshire, UK), in the diagnosis of tuberculous uveitis.

DESIGN

Prospective cohort to study diagnostic accuracy.

METHODS

We recruited consecutive new patients who presented with uveitis to a tertiary institution over a 2-year period. All patients underwent complete ocular examination and systemic evaluation, including T-SPOT.TB, QuantiFERON-TB Gold In-Tube, and tuberculin skin test. Patients were followed-up for a minimum of 1 year after completion of antituberculous therapy where indicated. The main outcome measures were the sensitivity, specificity and accuracy of each test, estimated using Bayesian latent class analysis (presented with 95% Bayesian credible intervals) (Crl). Prior information was obtained from published meta-analyses for diagnostic tests: QuantiFERON Gold In-Tube sensitivity (0.64, 0.59-0.69) and specificity (0.99, 0.99-1.00); T-SPOT. tuberculosis sensitivity (0.50, 0.33-0.67) and specificity (0.91, 0.88-0.93).

RESULTS

From our study in patients with uveitis, QuantiFERON-TB Gold In-Tube was more specific but slightly less sensitive (sensitivity: 0.64, 0.60-0.69; specificity: 0.995, 0.988-0.999) than T-SPOT.TB (sensitivity: 0.67, 0.60-0.74; specificity: 0.91, 0.88-0.93). However, QuantiFERON Gold In-Tube was significantly more accurate in identifying true-positive tuberculous uveitis cases than was T-SPOT.TB among discordant cases (QuantiFERON Gold In-Tube positive 98% vs T-SPOT.TB positive 76%; ratio 1.28, 95% Crl: 1.11-1.72, ie, 95% Crl >1.0, statistically significant).

CONCLUSION

Based on statistical decision theory, our head-to-head study suggests that QuantiFERON-TB Gold In-Tube is the first-line test that should be performed in preference to T-SPOT.TB (and the tuberculin skin test) for diagnosing tuberculous uveitis.

The usefulness of interferon-gamma release assay for diagnosis of tuberculosis-related uveitis in Korea

Purpose

To evaluate the usefulness of the interferon-gamma release assay (IGRA) for diagnosing tuberculosis (TB)-related uveitis (TRU).

Methods

Records from 181 patients with ocular signs and symptoms suggestive of TRU and intraocular inflammation of unknown etiology were reviewed. All subjects underwent clinical and laboratory testing, including IGRA, to rule out presence of underlying disease. A diagnosis of presumed TRU was made based on an internist's TB diagnosis and a patient's response to anti-TB therapy. Sensitivity, specificity, and positive predictive values of IGRA for TRU diagnosis were calculated. Clinical characteristics were compared between patients with positive and negative IGRA results.

Results

The sensitivity and specificity of IGRA for TRU were 100% and 72.0%, respectively. Mean age, percentage of patients with retinal vasculitis, and the anatomic type of uveitis were significantly different between patients with positive and negative IGRA results (all p ≤ 0.001). Positive IGRA rates and false-positive rates were significantly different between age and anatomic type groups (both p = 0.001). The positive predictive value of the IGRA among patients with intraocular inflammation was high (70%) when all of younger age (≤40 years), posterior uveitis, and retinal vasculitis were present.

Conclusions

The IGRA is useful for diagnosing TRU in the Korean population, especially when it is used as a screening test. Clinical characteristics, including younger age (≤40 years), posterior uveitis, and retinal vasculitis in IGRA-positive patients, increase the likelihood of the patient having TRU.

Diagnostic techniques for inflammatory eye disease: past, present and future: a review

Investigations used to aid diagnosis and prognosticate outcomes in ocular inflammatory disorders are based on techniques that have evolved over the last two centuries have dramatically evolved with the advances in molecular biological and imaging technology. Our improved understanding of basic biological processes of infective drives of innate immunity bridging the engagement of adaptive immunity have formed techniques to tailor and develop assays, and deliver targeted treatment options. Diagnostic techniques are paramount to distinguish infective from non-infective intraocular inflammatory disease, particularly in atypical cases. The advances have enabled our ability to multiplex assay small amount of specimen quantities of intraocular samples including aqueous, vitreous or small tissue samples. Nevertheless to achieve diagnosis, techniques often require a range of assays from traditional hypersensitivity reactions and microbe specific immunoglobulin analysis to modern molecular techniques and cytokine analysis. Such approaches capitalise on the advantages of each technique, thereby improving the sensitivity and specificity of diagnoses. This review article highlights the development of laboratory diagnostic techniques for intraocular inflammatory disorders now readily available to assist in accurate identification of infective agents and appropriation of appropriate therapies as well as formulating patient stratification alongside clinical diagnoses into disease groups for clinical trials.

Perspectives of Quantiferon TB Gold test among Indian practitioners: a survey

BACKGROUND

The aim of this study is to determine the preferences and perspectives regarding the Quantiferon TB Gold test for the diagnosis of tuberculosis (TB) in India. A survey was distributed among 46 uveitis specialists, rheumatologists, and pulmonologists with a minimum of 2 years experience in the management of tuberculosis, in order to restrict the respondents to specialists who have used this test in their practice in the diagnosis of tuberculosis. Topics included demographics, usage, logistics, effectiveness, and preferences related to the Quantiferon TB Gold test.

RESULTS

Among the 37 responders, there were 19 uveitis specialists, 9 rheumatologists, and 9 pulmonologists with the majority having more than 7 years of experience in treating tuberculosis. Latent TB was the most common type of tuberculosis reported by 81% of the responders. Although 92% agree that Quantiferon TB Gold assay is used for the diagnosis of latent TB, only 32% use this test always in their practice. Limiting factors include the higher cost (35.14%), limited data from countries endemic for TB and hence limited interpretation of results (32.43%), the inability to differentiate active and latent TB (32.43%), and technical issues related to the test (18.92%). A combination of the Mantoux test and Quantiferon TB Gold test was the preferred test for investigation in 51% of the responders rather than solo tests.

CONCLUSIONS

Within this group of specialists dealing with different forms of tuberculosis, perspectives of this test and preferences are many. The increased cost and limited data from India with respect to interpretation of the results are the most common limiting factors in using this test.

Aqueous cytokine and chemokine analysis in uveitis associated with tuberculosis

PURPOSE

The aim of this study was to study the aqueous cytokine and chemokine composition in patients with uveitis associated with tuberculosis (TAU).

METHODS

We present a prospective case series of consecutive new patients with active uveitis presenting at a single tertiary center (January 1, 2008-January 1, 2010). Patients with no ocular pathology other than cataracts were enrolled as non-inflammatory controls. Aqueous samples were taken from all study subjects and analyzed using a magnetic color-bead-based multiplex assay for cytokine and chemokine concentrations.

RESULTS

Twenty-five eyes of 25 patients with active uveitis with suspected tuberculosis (TB) and 23 non-inflammatory controls were enrolled. Ten patients tested positive on a tuberculin skin test and interferon-gamma release assay; all ten patients responded to anti-TB treatment with no recurrences (TAU). The remaining 15 eyes were negative for the above tests and had no other underlying causes for uveitis found on clinical evaluation and investigations; therefore, they were classified as "idiopathic uveitis" (IU). The TAU group showed significantly higher levels of interleukin-6 (IL-6; p=0.047), interleukin-8 (CXCL8; p=0.001), monokine induced by interferon-gamma (CXCL9; p=0.001), and interferon-gamma-induced protein 10 (IP-10 or CXCL10; p=0.002), compared to the controls. The IU group showed significantly higher levels of IL-6 (p=0.008), monocyte chemotactic protein-1 (CCL2; p=0.036), CXCL8 (p=0.001), and IL-9 (p=0.045), and significantly lower levels of IL-2 (p=0.011), IL-12 (p=0.001), and tumor necrosis factor (TNF)-α (p=0.001), compared to the controls. Heat map analysis revealed significant differences in aqueous cytokine and chemokine concentrations among the TAU patients, the IU patients, and the controls.

CONCLUSIONS

In our study population, aqueous cytokine and chemokine analyses suggest that subjects with uveitis associated with TB who respond to anti-TB therapy do not have an active ocular tuberculous infection, but rather an autoimmune-related ocular inflammation that may be triggered by TB.