QuantiFERON-TB Gold Assay on Plasma for Confirmation of Presumed Tuberculosis-Related Uveitis

Abstract

bThe QuantiFERON-TB Gold assay was used to measure interferon gamma levels in plasma from 4 patients with presumed tuberculosis-related uveitis before, during, and after antitubercular therapy. After treatment, all patients showed clinical improvement. The concentrations showed a reversion to an absence of interferon gamma in one case, decreased in two cases, and remained stable in one case. These results suggest that the QuantiFERON assay may be useful for tuberculosis-related uveitis diagnosis and follow-up.T uberculosis (TB)-related uveitis (TRU) is an uncommon form of extrapulmonary TB. TRU may have multiple clinical presentations, including anterior, intermediate, and posterior uveitis, panuveitis, retinitis and retinal vasculitis, neuroretinitis and optic neuropathy, and endophthalmitis (1). The lack of uniform criteria for the diagnosis of TRU accounts for the confusion concerning its management and the absence of reliable epidemiological data (1). The microbiological diagnosis of TRU is difficult, because most patients have no evidence of Mycobacterium tuberculosis in their ocular specimens. Indeed, in patients with TRU, tests detecting M. tuberculosis growth in cultures, acid-fast bacilli on smears, or M. tuberculosis DNA using PCR often yield no results. This may be due to a low level of inoculum or, more commonly, to immunedriven inflammation in the absence of active disease (latent infection). The lack of microbiological confirmation for presumed TRU makes indirect testing with QuantiFERON-TB Gold (QFT) the main support for this diagnosis (2,3). QFT is an interferon gamma (IFN-␥) release assay (IGRA) that measures the concentration of IFN-␥ obtained in response to the stimulation of whole blood with ESAT-6-, CFP-10-, and TB7.7-specific M. tuberculosis antigens (4). QFT results are not affected by former Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccination or immune reactivity to nontuberculous mycobacteria. Several studies have demonstrated its usefulness in supporting the diagnosis of pulmonary and extrapulmonary TB (5-8). Making the correct diagnosis has important therapeutic implications, since TRU must be treated with antitubercular therapy (ATT) to prevent vision loss (1-3, 9, 10). From this small case series, we present the results of QFT and ATT use in four immunocompetent patients with presumed TRU from an area (Sardinia, Italy) with low TB incidence.Approval from the local ethics committee/institutional review board was obtained. Three men and one woman with presumed TRU were examined at the Department of Surgical, Microsurgical, and Medical Sciences, Ophthalmology Unit, University of Sassari, Sassari, Italy, between September 2014 and September 2015. None had been vaccinated with BCG, and two reported an old close contact with active TB patients. The ophthalmic manifestations included cyclitis, vitreous inflammation, and vasculitis (patients 1 and 2), cyclitis and vitreous inflammation (patient 3), and uveopapillitis (patient 4). Overall, bilateral panuveitis was identified in thr...

The Collaborative Ocular Tuberculosis Study (COTS)-1: A Multinational Review of 447 Patients with Tubercular Intermediate Uveitis and Panuveitis

“…15 Furthermore, drug sensitivity of the presenting OTB strain was not established in most patients, and is not typically done because of the low yield of ocular-fluid derived cultures, long timeframe, and associated risks. 16,17 In TB endemic regions, physicians could be more inclined to initiate rather than withhold ATT because of a greater likelihood of a tuberculous aetiology. 14,18 This is not entirely unwarranted because untreated OTB could place the patient at risk of high visual morbidity.…”