Prevalence of Positive QuantiFERON-TB Gold In-Tube Test in Uveitis and its Clinical Implications in a Country Nonendemic for Tuberculosis

Diagnostic Utility of QuantiFERON-Gold Testing in Patients with Ocular Inflammation in a Low-Endemic Tuberculosis Region

PURPOSE

To evaluate the diagnostic value of QuantiFERON Gold (QFT-G) testing for ocular inflammation in a low prevalence tuberculosis (TB) area.

DESIGN

Diagnostic utility analysis.

METHODS

A review was performed for all uveitis patients who underwent QFT-G testing at the University of Colorado Eye Center from 2009 to 2022. Records were reviewed to assess QFT-G positivity rate and to identify which patients were tested for diagnostic purposes, defined as meeting the Standardization of Uveitis Nomenclature (SUN) criteria for tubercular uveitis (TBU): anterior uveitis with iris nodules, serpiginous-like choroiditis, choroidal nodule resembling a tuberculoma, multifocal choroiditis, or occlusive retinal vasculitis.

RESULTS

A total of 388 patients with uveitis underwent QFT-G testing, of which 17 (4.38%) were positive. Only one (5.88%) patient had true TBU with anterior uveitis with iris nodules. The remaining 16 (94.1%) patients did not meet SUN criteria for TBU and were incidentally found to be QFT-G positive during laboratory work-up prior to immunosuppression. The positive predictive value was 100% when QFT-G testing was performed in patients who met SUN criteria for TBU, whereas the positive predictive value was 0% for QFT-G testing performed in patients who did not meet SUN criteria for TBU.

CONCLUSION

In low prevalence areas, the majority of QFT-G positive tests in uveitis patients are coincidental and unrelated to their uveitic disease process. The diagnostic value of a TB test is likely to be minimal unless the SUN clinical criteria for tubercular uveitis are met.

Systemic and ocular outcomes in TB-immunoreactive patients receiving immunomodulatory therapy for non-infectious uveitis: a case-control study

BACKGROUND

Tuberculosis (TB)-immunoreactivity, measured in vivo (tuberculin skin test (TST)) or in vitro (interferon gamma release assay (IGRA)), can be found in latent, active or even following clearance of TB infection. In this case-control study, we compared the systemic and ocular outcomes between patients with or without TB-immunoreactivity, who received immunomodulatory therapy (IMT) for non-infectious uveitis.

METHODS

We retrospectively reviewed charts of patients with (cases) or without (controls) TB-immunoreactivity (TST±IGRA), who received conventional IMT for ≥6 months, for the treatment of non-infectious uveitis. Patients who received prior or concomitant anti-TB therapy were excluded. Systemic and ocular outcomes were compared between both groups.

RESULTS

36 cases and 70 controls (gender-matched and age-matched) were included. New-onset pulmonary or extrapulmonary TB developed in one case and none of the controls. Based on this outcome, the absolute risk increase for systemic TB reactivation was noted to be 0.028 (95% CI 0.005 to 0.051) and the number needed to harm was 36. The incidence of persistent or recurrent (worsening ≥2 grades) intraocular inflammation during IMT was comparable between both groups (cases 18/36, controls 35/70, p=1.0). A change in anatomical site of presentation at recurrence was not seen in any case, but in six controls (p=0.15). No new focal chorio-retinal lesions were noted in either group.

CONCLUSIONS

Conventional IMT has a very low risk of systemic TB reactivation, and no additional detrimental effect on ocular outcomes, in TB-immunoreactive patients with non-infectious uveitis.

Pathogenesis of Bacterial Uveitis

PURPOSE

To describe the pathogenesis and the general immune mechanisms of the most frequent causes of bacterial uveitis.

METHODOLOGY

Narrative review.

RESULTS

Both extra- and intracellular bacteria can induce uveitis, whereas intracellular bacteria are generally transported into the inner eye via cells of the innate immune system, mainly macrophages. Systemic adaptive immunity is usually induced before the bacteria are localized to the inner eye, and once T and B cells have detected the pathogens behind the blood-eye barriers they elicit an acute and/or chronic inflammatory response deteriorating visual acuity that can severely affect the non-regenerating, intraocular tissues.

CONCLUSIONS

An understanding of pathogenic mechanisms, and its correlation with clinical and imaging features, can facilitate early recognition of microbial factors and institution of appropriate therapy.

The immune response in tubercular uveitis and its implications for treatment: From anti-tubercular treatment to host-directed therapies

Tubercular uveitis (TB-uveitis) remains a conundrum in the uveitis field, which is mainly related to the diverse clinical phenotypes of TB-uveitis. Moreover, it remains difficult to differentiate whether Mycobacterium tuberculosis (Mtb) is present in the ocular tissues, elicits a heightened immune response without Mtb invasion in ocular tissues, or even induces an anti-retinal autoimmune response. Gaps in the immuno-pathological knowledge of TB-uveitis likely delay timely diagnosis and appropriate management. In the last decade, the immunopathophysiology of TB-uveitis and its clinical management, including experts' consensus to treat or not to treat certain conditions with anti-tubercular treatment (ATT), have been extensively investigated. In the meantime, research on TB treatment, in general, is shifting more toward host-directed therapies (HDT). Given the complexities of the host-Mtb interaction, enhancement of the host immune response is expected to boost the effectiveness of ATT and help overcome the rising burden of drug-resistant Mtb strains in the population. This review will summarize the current knowledge on the immunopathophysiology of TB-uveitis and recent advances in treatment modalities and outcomes of TB-uveitis, capturing results gathered from high- and low-burden TB countries with ATT as the mainstay of treatment. Moreover, we outline the recent progress of HDT development in the pulmonary TB field and discuss the possibility of its applicability to TB-uveitis. The concept of HDT might help direct future development of efficacious therapy for TB-uveitis, although more in-depth research on the immunoregulation of this disease is still necessary.

Usefulness of the QuantiFERON test for the diagnosis of tubercular uveitis and the predictions of response to antituberculosis treatment

AIMS

Few studies have evaluated the contribution of QuantiFERON test for the diagnosis of tubercular uveitis in non-endemic countries for tuberculosis (TB). The objective of the present study was to evaluate the value of the QuantiFERON test in a large cohort of patients with uveitis for both the diagnosis of tubercular uveitis and antituberculosis treatment (ATT) response prediction.

METHODS

A single-centre retrospective study including consecutive adult patients with uveitis who were prescribed a QuantiFERON test between January 2003 and December 2019 was performed. Adjusted ORs (aORs) were calculated between patients with uveitis responding and not responding to ATT according to the Collaborative Ocular Tuberculosis Study (COTS) group diagnostic criteria. Sensitivity (SE), specificity (Sp), and positive and negative predictive values of the QuantiFERON test were calculated.

RESULTS

A total of 1075 patients were included in the study; 178 (16.5%) were found positive using the QuantiFERON test. Among the 178 positive patients, 62 (35%) had a diagnosis of tubercular uveitis according to the updated COTS classification; all received ATT for 6 months; and 44/62 (71%) responded to ATT. A QuantiFERON test value of >2 IU/mL was associated with a greater chance of responding to ATT (aOR=36.7, 95% CI 7.2 to 185.9, p<0.001). The optimal threshold to maximise both Sp and SE for diagnosis of TB uveitis was 4 IU/mL.

CONCLUSION

One-sixth of the patients diagnosed with uveitis had a positive QuantiFERON test. The QuantiFERON threshold with the optimal SE and Sp for the diagnosis of tubercular uveitis was 4 IU/mL.

TRIAL REGISTRATION NUMBER

NCT03863782.

Antigen-Specific Intraocular Cytokine Responses Distinguish Ocular Tuberculosis From Undifferentiated Uveitis in Tuberculosis-Immunoreactive Patients

PURPOSE

To compare antigen-specific intraocular immune responses between different clinical phenotypes of tuberculin skin test (TST)-positive and TST-negative uveitis.

DESIGN

Single center, retrospective cross-sectional study.

METHODS

Patients requiring diagnostic or therapeutic vitrectomy for the management of intraocular inflammation were divided into 3 groups based on Standardization of Uveitis Nomenclature (SUN) classification criteria for tubercular uveitis. Group 1 included patients with ocular tuberculosis (OTB; n = 23) who were TST-positive patients, met the SUN criteria, and/or had a polymerase chain reaction (PCR)-positive test for TB. Group 2 included patients with uveitis of unknown origin (UNK; n = 24) who were undifferentiated TST-positive patients who had not met SUN criteria. Group 3 included non-TB uveitis patients (n = 24) who were TST-negative either with or without a well-defined non-TB diagnosis. Total vitreous cells were activated with Mycobacterium tuberculosis-specific Early Secreted Antigenic Target-6 (ESAT-6) or the retinal autoantigen, interphotoreceptor retinoid-binding protein peptide (pIRBP 1-20), stained for intracellular interferon gamma (IFNγ), tumor necrosis factor-alfa (TNFα), and interleukin 17 (IL-17), and analyzed by flow cytometry. Antigen-specific single and dual (polyfunctional) cytokine responses to ESAT-6 and IRBP were compared between the 3 groups.

RESULTS

All cytokine responses to ESAT-6 were higher in the UNK group compared with the non-TB control subjects, while all except IL-17 were comparable between the OTB and non-TB groups. Polyfunctional responses-IFNγ/IL-17 (P = .002), TNFα/IL-17 (P = .02), and TNFα/IFNγ (P = .01)-were significantly greater for UNK than the OTB group. Polyfunctional cells also produced more cytokine per cell than respective monofunctional cells. IRBP cytokine responses were comparable between different groups and were not affected by the clinical phenotype or duration of disease.

CONCLUSION

The intraocular polyfunctional cytokine response is stronger in undifferentiated TST-positive uveitis than in OTB patients, likely representing an exaggerated anti-TB immune response rather than active infection.

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.

Prevalence of Positive QuantiFERON-TB Test among Sarcoid Uveitis Patients and its Clinical Implications in a Country Non-endemic for Tuberculosis

AIM

To report on the prevalence and clinical implications of positive QuantiFERON-TB (QFT) test results in the diagnostic evaluation of a cohort of consecutive sarcoid uveitis patients in France.

DESIGN

Retrospective cross-sectional study.

METHODS

This study included consecutive sarcoid uveitis patients who all underwent QFT testing.

RESULTS

A total of 234 patients were included in the study, among them 28 (12%) were QFT-positive. Previously treated tuberculosis (TB) was documented in 2 patients. QFT-positive patients were older (59 ± 16 years vs. 51 ± 18 years, p = .025) and more in proportion to suffer from chronic uveitis and panuveitis compared to QFT-negative patients. Moderate and severe visual impairment were significantly more frequent in the QFT-positive group (35.7% vs. 18.9%, p = .049 and 25.0% vs. 9.2%, p = .022, respectively).

CONCLUSION

The significant proportion of QFT-positive patients (12%) in this large series of sarcoid uveitis patients makes us suggest not to exclude the diagnosis of sarcoidosis in case of positive QFT in a low-endemic country for tuberculosis, and to manage these patients early by initiating without delay systemic steroids associated with latent tuberculosis therapy.

Absence of Evidence as The Evidence Of Absence: The Curious Case of Latent Infection Causing Ocular Tuberculosis

Ocular tuberculosis (TB) is frequently considered as intraocular inflammation in the setting of latent TB, owing mainly to the absence of microbiological evidence of Mycobacterium tuberculosis in ocular fluid samples. Even though such lack of microbiological evidence, and of systemic signs of active TB disease, are suggestive of latent TB infection, molecular and rare histopathologic evidence of mycobacteria in the eye, and favourable response of ocular inflammation to anti-TB therapy point to the presence of active infection in ocular TB. Here, we discuss how intraocular inflammation in ocular TB is not merely an immunologic response to bacilli, but an active tuberculosis infection. We will discuss the reason for the frequent absence of microbiological evidence of TB in the eye in ocular TB and the diagnostic hierarchy to arrive at the diagnosis of this infectious uveitis entity.

BTS clinical statement for the diagnosis and management of ocular tuberculosis

The BTS clinical statement for the diagnosis and management of ocular tuberculosis (TB) draws on the expertise of both TB and and ophthalmic specialists to outline the current understanding of disease pathogenesis, diagnosis and management in adults. Published literature lacks high-quality evidence to inform clinical practice and there is also a paucity of data from animal models to elucidate mechanisms of disease. However, in order to improve and standardise patient care, this statement provides consensus points with the currently available data and agreed best practice.

The Association between QuantiFERON-TB Gold Test and Clinical Manifestations of Uveitis in the United States

PURPOSE

To report the prevalence of QuantiFERON-TB Gold (QFT-G) positivity among uveitis patients compared to general population and to evaluate the differences in clinical features of uveitis.

DESIGN

Retrospective cohort study.

METHODS

SETTING: Institutional.

PATIENT POPULATION

418 consecutive new uveitis patients, regardless of clinical suspicion, were tested for QFT-G.

OBSERVATION PROCEDURES

Demographics, TB risk factors, clinical characteristics of uveitis were collected.

MAIN OUTCOME MEASURES

The frequency of QFT-G positivity among uveitis patients and characteristic clinical features among QFT-G positive patients.

RESULTS

QFT-G positivity was found in 60/418 patients with uveitis (14.4%, 95% CI: 11.18 - 18.14) higher than the general US population (5%, 95% CI: 4.2 - 5.8, p<.001). Age, gender and residence were similar between QFT-G positive and negative groups. Uveitis patients with positive QFT-G were more likely to be foreign born or have a recent travel history (OR:5.84; 95% CI: 2.83 - 12.05; p<.001). QFT-G positive patients were more likely to present with granulomatous uveitis (OR 2.90; 95%CI 1.36 - 6.21; p=.006). No significant association was found with specific clinical features such as choroiditis, retinal vasculitis, occlusive vasculitis, and serpiginoid choroiditis (p>.05 for each). Prevalence of TB-uveitis based on treatment response was 1.19%.

CONCLUSIONS

Our study demonstrates significantly higher prevalence of QFT-G positivity among uveitis patients compared to average US population. Characteristic signs of TB uveitis reported in endemic countries were not seen in this cohort. Implications of higher prevalence of QFT-G positivity among uveitis patients require further investigation.

Characterization of and advanced diagnostic methods for ocular tuberculosis and tuberculosis

Tuberculosis (TB) is an airborne infection caused by Mycobacterium tuberculosis that usually affects the lungs. Timely treatment of active TB, diagnosis and prevention of latent TB are very important. However, extrapulmonary TB affects almost any tissues around the eye and orbit, and it then requires a high degree of suspicion to accurately diagnose. Diagnostic delays are common and may lead to morbidity. For ophthalmologists and infectious disease specialists, it is important to work together to accurately diagnose and treat ocular tuberculosis (OTB) to prevent vision loss. This review reports the latest advanced diagnostic methods for active TB and latent TB as well as various known manifestations of OTB. Important elements of diagnosis and treatment are also reviewed.

[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.