monica Losi

Diagnosing pleural tuberculosis (plTB) might be difficult due to limited sensitivity of conventional microbiology tools. As M. tuberculosis (MTB)-specific T cells are recruited into pleural space in plTB, their detection may provide useful clinical information. To this aim, in addition to standard diagnostic tests, we used the QuantiFERON-TB Gold In-Tube (QFT-IT) test in blood and pleural effusion (PE) samples from 48 patients with clinical suspicion of plTB, 18 (37.5%) of whom had confirmed plTB. Four of them (22.2%) tested positive with a nucleic acid amplification test for MTB. The tuberculin skin test was positive in most confirmed plTB cases (88.9%). Positive QFT-IT tests were significantly more frequent in patients with confirmed plTB, as compared to patients with an alternative diagnosis, both in blood (77.7 vs 36.6%, p=0.006) and in PE samples (83.3% vs 46.6%, p=0.02). In addition, both blood and PE MTB-stimulated IFN-γ levels were significantly higher in plTB patients (p=0....

The tuberculin skin test (TST) does not discriminate between recent and remote latent tuberculosis infection (LTBI). This study was carried out to test two interferon-γ (IFN-γ)-based blood assays in recent contacts with high prevalence of remote LTBI. We performed a contact tracing investigation in a nursing home for the elderly, where elderly patients were exposed to a case of pulmonary tuberculosis. TST, QuantiFERON-TB Gold (QFT-G) and T-SPOT.TB (TS.TB) were performed 8 weeks after the end of potential exposure. IFN-γ measurements were recorded and correlation with exposure was evaluated. Twenty-seven (37.5%), 32 (44.4%) and 16 (22.2%) subjects were TST, TS.TB and QFT-G positive, respectively; agreement between TS.TB and QFT-G was good among exposed subjects only (κ=0.915, 0.218 in unexposed, p<0.001). When amounts of IFN-γ were corrected for the number of producing T cells, specific IFN-γ production was significantly different between exposed and unexposed individuals (16.75±5...

Background. I pazienti affetti da emolinfopatie maligne presentano un aumentato rischio di progressione da infezione tubercolare latente (ITBL) a tubercolosi (TB) attiva dovuto sia alla patologia di base sia a concomitanti trattamenti immunosoppressivi. Il test cutaneo tubercolinico (TCT) presenta una ridotta sensibilità in questi pazienti a causa di una energia cutanea. L’utilizzo dei test basati sulla produzione di interferone-gamma (IFN-γ) dopo stimolazione antigene-specifica potrebbe rappresentare uno strumento diagnostico sia per la diagnosi di ITBL sia di TB attiva in questa popolazione. Scopo dello studio era valutare la sensibilità dei test QuantiFERON-TB Gold-In tube (QFT-G IT, Cellestis,Victoria,Australia) e T-SPOT.TB (TS.TB,Oxford Immunotech,Abingdon,UK) basati sulla produzione “in vitro” di IFN-γ da parte delle cellule-T in risposta alla stimolazione con antigenimicobatterici, ESAT-6 e CFP10, rispetto al TCT in una popolazione di pazienti affetti da emolinfopatia maligna...

Two new blood tests are today available for diagnosing latent tuberculosis infection. Both tests are based on the release of interferon-gamma from M. tuberculosis-specific T cells. These tests, QuantiFERON-TB Gold and T-SPOT.TB, are certainly more specific compared to the tuberculin skin test, and possibly more sensitive in some subgroups of patients; they might represent a crucial tool for tuberculosis control and elimination.

A27 DIAGNOSIS OF ACTIVE AND LATENT TUBERCULOSIS: NOVEL AND IMPROVED TECHNIQUES / Sunday, May 15/8:15 AM-10:45 AM / Room 601 (Street Level), Colorado Convention Center ... Role Of The Qft-It Assay For The Diagnosis Of Latent Tuberculosis Infection Among ...

In idiopathic pulmonary fibrosis (IPF), lung accumulation of excessive extracellular iron and macrophage haemosiderin may suggest disordered iron homeostasis leading to recurring microscopic injury and fibrosing damage.The current study population comprised 89 consistent IPF patients and 107 controls. 54 patients and 11 controls underwent bronchoalveolar lavage (BAL). Haemosiderin was assessed by Perls' stain, BAL fluid malondialdehyde (MDA) by high-performance liquid chromatography, BAL cell iron-dependent oxygen radical generation by fluorimetry and the frequency of hereditary haemochromatosis HFE gene variants by reverse dot blot hybridisation.Macrophage haemosiderin, BAL fluid MDA and BAL cell unstimulated iron-dependent oxygen radical generation were all significantly increased above controls (p<0.05). The frequency of C282Y, S65C and H63D HFE allelic variants was markedly higher in IPF compared with controls (40.4% versus 22.4%, OR 2.35, p=0.008) and was associated with...

/ Thematic Poster Session / Sunday, May 16/8:15 AM-4:00 PM / Area A51 DIAGNOSIS OF LATENT AND ACTIVE TUBERCULOSIS ... L, Hall G (First Level), Morial Convention Center ... ROLE OF QUANTIFERON-TB GOLD TEST IN THE DIAGNOSIS OF ACTIVE TUBERCULOSIS

IP-10 has potential as a diagnostic marker for infection with Mycobacterium tuberculosis, with comparable accuracy to QuantiFERON-TB Gold In-Tube test (QFT-IT). The aims were to assess the sensitivity and specificity of IP-10, and to evaluate the impact of co-morbidity on IP-10 and QFT-IT. 168 cases with active TB, 101 healthy controls and 175 non-TB patients were included. IP-10 and IFN-γ were measured in plasma of QFT-IT stimulated whole blood and analyzed using previously determined algorithms. A subgroup of 48 patients and 70 healthy controls was tested in parallel with T-SPOT.TB IP-10 and QFT-IT had comparable accuracy. Sensitivity was 81% and 84% with a specificity of 97% and 100%, respectively. Combining IP-10 and QFT-IT improved sensitivity to 87% (p < 0.0005), with a specificity of 97%. T-SPOT.TB was more sensitive than QFT-IT, but not IP-10. Among non-TB patients IP-10 had a higher rate of positive responders (35% vs 27%, p < 0.02) and for both tests a positive response was associated with relevant risk factors. IFN-γ but not IP-10 responses to mitogen stimulation were reduced in patients with TB and non-TB infection. This study confirms and validates previous findings and adds substance to IP-10 as a novel diagnostic marker for infection with M. tuberculosis. IP-10 appeared less influenced by infections other than TB; further studies are needed to test the clinical impact of these findings.

Young children exposed to tuberculosis have a high risk of progression to severe tuberculosis disease, but diagnosis of recent infection is hindered by the poor sensitivity of the tuberculin skin test. Whether new blood tests can detect latent infection in this vulnerable group is unknown because there is no gold standard. We monitored a tuberculin skin test–negative infant whose mother had infectious multidrug-resistant tuberculosis with enzyme-linked immunospot, a blood test that enumerates Mycobacterium tuberculosis–specific T cells. The enzyme-linked immunospot test became persistently positive by 6 months, and 18 months later the child developed active tuberculosis despite appropriate chemoprophylaxis. At this point, the magnitude of the enzyme-linked immunospot response increased >10-fold. Our findings demonstrate that this blood test detected latent infection with dormant, yet viable, bacilli and illustrate how enzyme-linked immunospot could improve diagnosis of childhood ...

BACKGROUND. The accurate diagnosis of latent tuberculosis infection reduces the risk of progression to severe disseminated disease. However, in young children, a major limitation of the standard tuberculin skin test is that false-negative results cannot be detected. The new interferon-γ release assays QuantiFERON-TB Gold (Cellestis Carnegie Victoria, Australia), QuantiFERON-TB In-Tube (Cellestis), and T-SPOT.TB (Oxford Immunotec, Abingdon, United Kingdom) show promise of greater accuracy, but they may also be affected by impaired cellular immunity, resulting in indeterminate results (ie, insufficient response in positive-control wells). OBJECTIVE. To evaluate the impact of age on the performance of interferon-γ release assays when used in a routine hospital setting among children tested for suspected active or latent TB infection. METHODS. We retrospectively studied 496 children 0 to 19 years of age who had been tested with the tuberculin skin test and at least 1 interferon-γ releas...

A simple and sensitive diagnostic test for active tuberculosis would greatly improve the efficacy of tuberculosis control strategies especially in developing endemic countries. Such a test would be particularly useful in patients in whom microbiological diagnosis using the traditional tools is either difficult or delayed such as immunosuppressed patients and very young children. On the basis of our findings M A Phadke and N A Kshirsagar consider the tuberculin skin test although less specific more sensitive and suitable for resource-limited settings than the new interferongamma-based assays. Both types of test identify individuals with latent tuberculosis infection; however only a few people latently infected also have (or will have in the future) active disease. Thus figure 1 of our paper does not show that the blood tests are less sensitive but indicates that the skin test is less specific for diagnosing latent tuberculosis. (excerpt)

Accurate detection and adequate treatment of latent tuberculosis infection represent a fundamental cornerstone to reduce the incidence of tuberculosis, in particular in low-incidence countries and among high-risk (i.e., immunosuppressed) individuals. Until recently, however, only the century-old tuberculin skin test was available as a diagnostic tool; its poor specificity and low sensitivity among immunosuppressed individuals has been a major limit to the implementation of effective tuberculosis control strategies. In the last years, the achievements of basic research on the genetics and immunology of Mycobacterium tuberculosis infection rapidly translated into clinical practice two elements of the vast amounts of knowledge acquired. First, the identification and use of specific antigens, which are absent in the tuberculosis vaccine and in most nontuberculous mycobacteria; and second, the identification of IFN-gamma as the main fundamental cytokine implicated in the effective immune response against M. tuberculosis. In an incredibly powerful combination, this new knowledge has been applied to enzyme-linked immunospot (ELISpot) technology, the most sensitive technique to quantify an in vitro antigen-specific cellular immune response. In only a few years, a new commercial, regulatory-approved, diagnostic assay has entered clinical practice as a substitute to the tuberculin skin test. The T-SPOT.TB test has already been applied to several hundreds of patients in the context of controlled clinical trials in different countries and prevalence areas, showing improved specificity and sensitivity in the diagnosis of latent tuberculosis infection over the skin test, in particular in those settings where the diagnosis is most needed.

A new immunochromatographic membrane assay for detecting Legionella pneumophila serogroup 1 antigen in urine samples (Binax Now Legionella Urinary Antigen Test; Binax, USA) was evaluated. Its sensitivity, specificity and level of agreement with the Binax enzyme immunoassay were compared using nonconcentrated and concentrated urine samples. The overall agreement between the two tests was 98.1%; the specificity of both was 100%.

Immunocompromised persons infected with Mycobacterium tuberculosis (MTB) have increased risk of tuberculosis (TB) reactivation, but their management is hampered by the occurrence of false-negative results of the tuberculin skin test (TST). The T-cell interferon (IFN)-gamma release blood assays T-SPOT.TB (TS.TB) [Oxford Immunotec; Abingdon, UK] and QuantiFERON-TB Gold In-Tube (QFT-IT) [Cellestis Ltd; Carnegie, VIC, Australia] might improve diagnostic accuracy for latent TB infection (LTBI) in high-risk persons, although their performance in different groups of immunocompromised patients is largely unknown. Over a 1-year period, we prospectively enrolled patients in three different immunosuppressed groups, as follows: 120 liver transplantation candidates (LTCs); 116 chronically HIV-infected persons; and 95 patients with hematologic malignancies (HMs). TST, TS.TB, and QFT-IT were simultaneously performed, their results were compared, and intertest agreement was evaluated. Overall, TST provided fewer positive results (10.9%) than TS.TB (18.4%; p < 0.001) and QFT-IT (15.1%; p = 0.033). Significantly fewer HIV-infected individuals had at least one positive test (9.5%) compared with LTCs (35.8%; p < 0.001) and patients with HMs (29.5%; p < 0.001). Diagnostic agreement between tests was moderate (kappa = 0.40 to 0.65) and decreased in the HIV-infected group when the results of the TS.TB were compared with either TST (kappa = 0.16) or QFT-IT (kappa = 0.19). Indeterminate blood test results due to low positive control values were significantly more frequent with QFT-IT (7.2%) than with TS.TB (0.6%; p < 0.001). Blood tests identified significantly more…

... despite limitations in test specificity, it may currently be the best option to rapidly diagnose smear negative TB ... CHRISTOPH LANGE MARTIN ERNST ULF GREINERT CLAUDIA JAFARI BARBARA KALSDORF ALAN STRASSBURG Research Center Borstel Borstel, Germany AIK ...