Role of Extracellular Mycobacteria in Blood-Retinal Barrier Invasion in a Zebrafish Model of Ocular TB

Intraocular inflammation following mycobacterial dissemination to the eye is common in tuberculosis (TB)-endemic countries. However, the early host–pathogen interactions during ocular dissemination are unknown. In this study, we investigated the early events during mycobacterial invasion of the blood-retinal barriers (BRBs) with fluorescent-tagged Mycobacterium marinum (Mm), host macrophages, and retinal vasculature in a zebrafish model of ocular TB. We found that Mm invaded the vascular endothelium in either the extracellular or intracellular (inside phagocytes) state, typically 3–4 days post-injection (dpi). Extracellular Mm are phagocytosed in the retinal tissue and progress to form a compact granuloma around 6 dpi. Intracellular Mm crossing the BRBs are likely to be less virulent and either persist inside solitary macrophages (in most cases) or progress to loosely arranged granuloma (rarely). The early interactions between mycobacteria and host immune cells can thus determine the course of disease during mycobacterial dissemination to the eye.

A clinical study of optic nerve involvement in patients with tuberculosis attending a tertiary health care center in North East

Background: To screen for ocular finding of optic nerve involvement in patients with tuberculosis and documents these findings.Methods: The hospital based observational study was carried out in a tertiary care hospital in Assam for the duration of July 2018 to June 2019 in 384 diagnosed cases of tuberculosis patients who fulfil the inclusion criteria during the study period.Results: 11 cases with optic nerve involvement was found out of 384 tuberculosis patients. Most common presenting complain was blurring of vision. Unilateral involvement was maximum. Most common finding was disc oedema. Ocular TB cases was higher in extrapulmonary TB patients.Conclusions: Diagnosis of ocular Tb is mainly presumptive, based on history, clinical examination, adjunctive diagnostic tests and response to anti tuberculous therapy. Amongst 384 TB cases ocular manifestations were found in 11 cases and therefore, we can conclude that ocular manifestations hold significance in extra pulmonary manifestations of TB. So, TB patients need to have routine ocular examination for the early diagnosis and timely management.

Role of extracellular mycobacteria in blood-retinal barrier invasion in a zebrafish model of ocular TB

Intraocular inflammation following mycobacterial dissemination to the eye is common in tuberculosis (TB)-endemic countries. However, the early host-pathogen interactions during ocular dissemination are unknown. In this study, we investigate the early events during mycobacterial invasion of the blood-retinal barriers (BRB) with fluorescent tagged Mycobacterium marinum ( Mm ), host macrophages and retinal vasculature in a zebrafish model of ocular TB. We found that Mm invaded the vascular endothelium either in extracellular or intracellular (inside phagocytes) state, typically 3-4 days post-injection (dpi). Extracellular Mm are phagocytosed in the retinal tissue, and progress to form a compact granuloma around 6 dpi. Intracellular Mm crossing the BRB are likely to be less virulent, and either persist inside solitary macrophages (most cases), or progress to loosely arranged granuloma (rare). The early interactions between mycobacteria and host immune cells can thus determine the course of disease during mycobacterial dissemination to the eye.

Intraocular tuberculosis, a challenge in diagnosis and treatment

Ocular tuberculosis (TB) is an extrapulmonary tuberculous condition and has variable manifestations. The incidence of TB is still high in developing countries, and a steady increase in new cases has been observed in industrial countries as a result of the growing number of immunodeficient patients and migration from developing countries. Choroidal granuloma is a rare and atypical location of TB. We present a case of a presumptive choroidal granuloma. This case exposes that diagnosis can be remarkably challenging when there is no history of pulmonary TB. The recognition of clinical signs of ocular TB is extremely important since it provides a clinical pathway toward tailored investigations and decision making for initiating anti-TB therapy and to ensure a close follow-up to detect the development of any complication.

Miliary Tuberculosis with Tubercular Uveitis Presenting as Fever of Unknown Origin: A Case Report

Miliary tuberculosis is a form of disseminated tuberculosis, which is more frequent in immunocompromised patient. Ocular involvement of mycobacterium tuberculosis is also an uncommon presentation of disseminated tuberculosis. Tubercular uveitis is most frequent form of ocular tuberculosis. If treatment is delayed, it may cause loss of vision. In many case of the systemic TB with ocular involvement, there may be no eye symptoms in early stage. On the other hand, many cases of ocular TB may not have any evidence of systemic TB. Here we have described a case of miliary tuberculosis with ocular uveitis who initially presented with fever without any significant physical findings and later developed eye symptoms including diminished vision. Bangladesh J Child Health 2019; VOL 43 (2) :126-130

Bilateral optic neuritis secondary to presumed ocular tuberculosis in immunocompetent adults

This case series aims to discuss cases of bilateral optic neuritis secondary to presumed ocular tuberculosis (TB) in two immunocompetent adults. Ocular TB has been associated with optic neuritis, but bilateral cases in immunocompetent individuals are rarely seen. We report a case series of two young healthy adults with bilateral painless optic neuritis as the presenting feature of ocular TB. Clinical examination, TB tests, and angiographic studies supported the diagnosis. All patients were started on anti-TB medication followed by oral prednisolone and had visual improvement a few weeks after treatment. As a conclusion, these cases highlight an atypical case of ocular TB presentation in immunocompetent individuals and thorough investigation is pertinent to preserve the visual function.

A Zebrafish Model for Ocular Tuberculosis

Ocular tuberculosis (TB) commonly causes severe inflammation and vision loss in TB-endemic countries. The mechanism by which tuberculous infection becomes established in the eye is poorly understood. We used Mycobacterium marinum-infected zebrafish larvae to study the early pathogenesis of ocular TB and found hematogenous bacterial seeding of the eye despite a functional blood retinal barrier. Prototypical early granulomas formed that involved the retinal vasculature and retinal pigment epithelium-choroid complex; characteristic locations for human ocular TB. Peripheral blood monocytes were recruited to the growing granuloma suggesting that the immune privileged nature of the eye is breached by this inflammatory focus.Conflict of interestnone disclosedFundingThis work was supported in part by a ‘Short-term fellowship’ to SB by Department of Health Research, Government of India.

A CASE OF DISSEMINATED TUBERCULOSIS WITH OCULAR INVOLVEMENT

Disseminated Tuberculosis (DTB) refers to tubercular involvement of two or more non-contiguous sites and is commonly associated with immunocompromised state. It is an unusual presentation of Tuberculosis (TB), especially in the absence of immunodeficiency. 1.4% of patients with Pulmonary Tuberculosis (PTB) develop ocular manifestations but many patients with ocular TB have no evidence of PTB. Tuberculosis can cause a wide variety of ophthalmic findings, ranging from the ocular surface through the optic nerve and to the central nervous system. In this article, we report a case of Disseminated Tuberculosis with ocular involvement in a 5years old female. Our case is unique for the presence of bilateral squint, unilateral nebular type of corneal opacity, bilateral iritis with posterior synechiae and cataract at the same time. It lays emphasis on the fact that a patient with tuberculosis should be screened for multiple foci.