Insights into the molecular pathogenesis of ocular tuberculosis

Validation of the Online Collaborative Ocular Tuberculosis Study Calculator for Tubercular Uveitis

Importance

This was the first study, to the authors' knowledge, to statistically evaluate the predictive accuracy of Collaborative Ocular Tuberculosis Study (COTS) calculator in guiding initiation of antitubercular therapy (ATT) in patients with clinically suspicious tubercular uveitis (TBU) in an international cohort.

Objective

To evaluate the accuracy of a score of 4 or greater on the online COTS calculator in recommending ATT initiation.

Design, Setting, and Participants

This study was an evaluation of a diagnostic test or technology. Data input required for the COTS calculator were extracted from the COTS-1 study dataset, which comprised retrospective, observational records of patients with TBU who were monitored for 12 months after treatment. Patients were recruited from international ophthalmic centers. In the absence of a traditional criterion standard, the 12-month treatment response to ATT was used to classify patients as disease positive or negative. The accuracy of clinicians at the ATT decision-making stage in the COTS-1 study was set against COTS calculator scores of 4 or greater. Diagnostic accuracy metrics, including sensitivity, specificity, positive predictive value (PPV), precision, recall, and F1 score, were computed. Data collected from January 2004 to December 2014 were analyzed.

Exposures

COTS calculator to guide initiation of ATT in patients with TBU.

Main Outcomes and Measures

Comparison of accuracy between clinician judgment and the COTS calculator, analyzed at varying scores and further stratified by tuberculosis endemicity.

Results

Of the 492 participants (mean [SD] age, 42.3 [19.0] years; 233 male [47.3%]), application of the COTS calculator identified 225 (45.7%) with high or very high probability to start ATT (score = 4 or 5) and 111 (22.5%) with very high probability alone (score = 5). COTS-5 exhibited the highest specificity (88.7%; 95% CI, 81.4%-93.8%) compared with clinician judgment (29.6%; 95% CI, 21.4%-38.8%), and clinician judgment led in sensitivity (95.5%; 95% CI, 92.9%-97.4%) compared with COTS-5 (26%; 95% CI, 21.6%-30.7%). COTS-4 and COTS-5 balanced specificity (64.3%; 95% CI, 54.9%-73.1%) and sensitivity (48.8%; 95% CI, 43.7%-54%). PPV and sensitivity were consistently higher in the endemic group for all 3 tests.

Conclusions and Relevance

Results of this diagnostic study suggest that the COTS calculator (score ≥4) was more specific than clinician judgment for ATT initiation. Although clinician judgment is a good first step to identify all potential true positives (with high sensitivity), a second consultation with COTS-5 (with high PPV) may lead to less false positives. This tool, apt for high-prevalence, low-resource settings, recommends ATT more selectively for genuine TBU cases. Large prospective studies are essential to explore potential improvements in the calculator's sensitivity.

Epidemiology and Clinical Characteristics of Ocular Tuberculosis in the United States, 1993-2019

Background

Data regarding ocular tuberculosis (OTB) in the United States have not been previously reported. We evaluated trends of OTB compared with other extrapulmonary TB (EPTB).

Methods

We estimated the proportion of all EPTB cases (with or without concurrent pulmonary involvement) with OTB reported to the National Tuberculosis Surveillance System during 1993-2019. We compared demographics and clinical characteristics of people with OTB and other EPTB during 2010-2019. P values were calculated by chi-square test for categorical variables and Kruskal-Wallis for continuous variables.

Results

During 1993-2019, 1766 OTB cases were reported, representing 1.6% of 109 834 all EPTB cases: 200 (0.5% of 37 167) during 1993-1999, 395 (1.0% of 41 715) during 2000-2009, and 1171 (3.8% of 30 952) during 2010-2019. In contrast to persons with other EPTB, persons with OTB were older (median, 48 vs 44 years; P < .01), more likely to be US-born (35% vs 28%; P < .01), more likely to have diabetes (17% vs 13%; P < .01), and less likely to have HIV (1% vs 8%; P < .01). OTB was less likely to be laboratory confirmed (5% vs 75%; P < .01), but patients were more likely to be tested by interferon gamma release assay (IGRA; 84% vs 56%; P < .01) and to be IGRA positive (96% vs 80%; P < .01).

Conclusions

Reported OTB increased during 1993-2019 despite decreasing TB, including EPTB; the largest increase occurred during 2010-2019. OTB was rarely laboratory confirmed and was primarily diagnosed in conjunction with IGRA results. More research is needed to understand the epidemiology of OTB to inform clinical and diagnostic practices.

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.

Presumed tuberculosis-related scleritis

AIMS

To evaluate the clinical characteristics and therapeutic outcome of patients with recurrent scleritis of unknown demonstrable aetiology and positive QuantiFERON-TB Gold In-Tube test (QFT).

METHODS

Retrospective chart review of the demographic, clinical, laboratory and therapeutic outcome data of 15 patients. Clinical characteristics as well as remission rate after standard antituberculous therapy (ATT) were assessed.

RESULTS

There were 9 men and 6 women with a mean age of 48.9 years (range, 32-73). Scleritis was diffuse in 10 patients (66.6%) and nodular in 5 patients (33.3%), 1 of them with concomitant posterior scleritis. It was bilateral in 7 patients (46.6%) and recurrent in all of them. Scleritis appeared after prior uveitis (10 patients, 66.6%) and/or with concomitant uveitis (5 patients, 33.3%) or peripheral keratitis (5 patients, 33.3%). Previous ocular surgery was found in 7 patients (46.6%). Previous extraocular tuberculosis (TB) infection or previous TB contact was detected in 11 patients (73.3%). No radiologic findings of active extraocular TB were detected. ATT was used in 15 patients, sometimes with the addition of systemic corticosteroids (5 patients) and methotrexate (1 patient); 14 patients achieved complete remission (93.3%).

CONCLUSION

Presumed TB-related scleritis may appear in recurrent scleritis of unknown origin and positive QFT. It may occur after prior uveitis and/or concomitantly with uveitis or peripheral keratitis, and it may be triggered by previous ocular surgery. No patients had evidence of concurrent active extraocular infection, although many had previous TB infection or TB contact. ATT was effective, sometimes with the addition of systemic corticosteroids and methotrexate.

Histological Diagnosis of Ocular and Periocular Tuberculosis 1945 - 2020

BACKGROUND

Ocular tuberculosis is a rare but important differential diagnosis for inflammatory conditions of all eye tissues, including the ocular surface and adnexa. Tissue diagnostics may prove challenging as some ocular tissues are difficult to biopsy and the detection of pathogens may be insensitive. We were interested in how many cases in the archive of the ophthalmopathological laboratory had been diagnosed with (peri)ocular tuberculosis since 1945.

MATERIALS AND METHODS

Retrospective analysis of historical records and specimens of the ophthalmopathology laboratory of the eye department at Freiburg university hospital. Systematic re-evaluation of available slides for presence of granuloma, necrosis, giant cells, acid fast bacteria, and chronic as well as acute inflammation, plus comparison of current and historic evaluations. In addition, we describe a recent case with tuberculoma of the iris.

RESULTS

There were 50,418 records archived since 1945, of which 23 specimens taken from 22 patients had been diagnosed as (peri)ocular tuberculosis. Of these, 22 (96%) were archived and available for re-interpretation. Four specimens (17%) had been excised from children. The most common tissues were enucleated eye globes (10/23, 44%), followed by the lacrimal sac (5/23, 22%) and conjunctiva (2/23, 9%). The most frequent histopathological findings were granulomas (23/23, 100%), chronic inflammation (22/23, 96%), giant cells (21/23, 91%), and necrosis (14/23, 61%). An acute inflammatory response was found in 4/23 specimens (17%). Ziehl-Neelsen stains for acid-fast bacteria had been performed in five cases, of which three were positive (60%). The greatest discrepancy between current and historical findings related to the presence of necrosis (59% consensus). In other findings, the consensus was high (78 - 96%). In a recent case of a patient with wasting syndrome attributed to lymphoma, histopathological workup of an iris tumour led to the diagnosis of tuberculosis.

CONCLUSION

Ocular tuberculosis is a rare but important histopathological differential diagnosis. In the available specimens, the classic finding of necrotizing inflammation was rarest and showed least consensus on histological re-evaluation. Other typical findings, such as giant cells and a predominantly lymphocytic infiltrate, are sometimes not found even with proven presence of Mycobacterium tuberculosis. They should not be considered essential in cases where there is strong clinical suspicion.

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.