Estimating diagnostic accuracy of tests for latent tuberculosis infection without a gold standard among healthcare workers

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Higher Frequency of T-Cell Response to M. tuberculosis Latency Antigen Rv2628 at the Site of Active Tuberculosis Disease than in Peripheral Blood

RATIONALE: Due to the invasive nature of the procedures involved, most studies of Mycobacterium tuberculosis (Mtb)-specific immunity in humans have focused on the periphery rather than the site of active infection, the lung. Recently, antigens associated with Mtb-latency and -dormancy have been described using peripheral blood (PB) cells; however their response in the lung is unknown. The objective of this report was to evaluate, in patients prospectively enrolled with suspected active tuberculosis (TB), whether the latency antigen Rv2628 induces local-specific immune response in bronchoalveolar lavage (BAL) cells compared to PB cells. MATERIAL/METHODS: Among the 41 subjects enrolled, 20 resulted with active TB. Among the 21 without active disease, 9 were defined as subjects with latent TB-infection (LTBI) [Quantiferon TB Gold In-tube positive]. Cytokine responses to Rv2628 were evaluated by enzyme linked immunospot (ELISPOT) assay and flow cytometric (FACS) analysis. RD1-secreted antigen stimulation was used as control. RESULTS: There was a significantly higher frequency of Rv2628- and RD1-specific CD4+ T-cells in the BAL of active TB patients than in PB. However the trend of the response to Rv2628 in subjects with LTBI was higher than in active TB in both PB and BAL, although this difference was not significant. In active TB, Rv2628 and RD1 induced a cytokine-response profile mainly consisting of interferon (IFN)-γ-single-positive over double-IFN-γ/interleukin (IL)-2 T-cells in both PB and BAL. Finally, BAL-specific CD4+ T-cells were mostly effector memory (EM), while peripheral T-cell phenotypes were distributed among naïve, central memory and terminally differentiated effector memory T-cells. CONCLUSIONS: In this observational study, we show that there is a high frequency of specific T-cells for Mtb-latency and RD1-secreted antigens (mostly IFN-γ-single-positive specific T-cells with an EM phenotype) in the BAL of active TB patients. These data may be important for better understanding the pathogenesis of TB in the lung

Methylated HBHA produced in <i>M. smegmatis</i> discriminates between active and non-active tuberculosis disease among RD1-responders

Background. A challenge in tuberculosis (TB) research is to develop a new immunological test that can help distinguish, among subjects responsive to QuantiFERON TB Gold In tube (QFT-IT), those who are able to control Mtb replication (remote LTBI, recent infection and past TB) from those who cannot (active TB disease). IFN-γ; response to the Heparin-binding-hemagglutinin (HBHA) of Mtb has been associated with LTBI, but the cumbersome procedures of purifying the methylated and immunological active form of the protein from Mtb or M. bovis Bacillus Calmette et Guerin (BCG) have prevented its implementation in a diagnostic test. Therefore, the aim of the present study was to evaluate the IFN-γ response to methylated HBHA of Mtb produced in M. smegmatis (rHBHAms) in individuals at different stages of TB who scored positive to QFT-IT. Methodology/Principal Findings. 87 individuals at different stages of TB who scored positive to QFT-IT were selected. IFN-γ response to in vitro whole blood stimulation with rHBHAms was evaluated by short-term and long-term tests and detected by ELISA or flow cytometry. We demonstrated that the IFN-γ response to rHBHAms is mediated by CD4+ T-cells with an effector-memory phenotype. This response, evaluated by short-term-tests, is significantly lower in active TB than in remote LTBI (p = 0.0010) and past TB (p = 0.0152). These results were confirmed by long-term tests. The qualitative data confirmed that IFN-γ responses higher than the cut-off point identified by ROC analysis are associated with the status of non-active disease. Conclusions. In this study we show that the T-cell response to a recombinant and methylated HBHA of Mtb produced in M. smegmatis is useful to discriminate between active and non-active TB disease among those responsive to QFT-IT in a whole blood system. Further studies are needed to improve the accuracy of the assay

Methylated HBHA Produced in M. smegmatis Discriminates between Active and Non-Active Tuberculosis Disease among RD1-Responders

A challenge in tuberculosis (TB) research is to develop a new immunological test that can help distinguish, among subjects responsive to QuantiFERON TB Gold In tube (QFT-IT), those who are able to control Mtb replication (remote LTBI, recent infection and past TB) from those who cannot (active TB disease). IFN-\u3b3 response to the Heparin-binding-hemagglutinin (HBHA) of Mtb has been associated with LTBI, but the cumbersome procedures of purifying the methylated and immunological active form of the protein from Mtb or M. bovis Bacillus Calmette et Guerin (BCG) have prevented its implementation in a diagnostic test. Therefore, the aim of the present study was to evaluate the IFN-\u3b3 response to methylated HBHA of Mtb produced in M. smegmatis (rHBHAms) in individuals at different stages of TB who scored positive to QFT-IT

New tools for detecting latent tuberculosis infection: evaluation of RD1-specific long-term response

<p>Abstract</p> <p>Background</p> <p>Interferon-gamma (IFN-γ) release assays (IGRAs) were designed to detect latent tuberculosis infection (LTBI). However, discrepancies were found between the tuberculin skin test (TST) and IGRAs results that cannot be attributed to prior Bacille Calmètte Guerin vaccinations. The aim of this study was to evaluate tools for improving LTBI diagnosis by analyzing the IFN-γ response to RD1 proteins in prolonged (long-term response) whole blood tests in those subjects resulting negative to assays such as QuantiFERON-TB Gold In tube (QFT-IT).</p> <p>Methods</p> <p>The study population included 106 healthy TST⁺individuals with suspected LTBI (recent contact of smear-positive TB and homeless) consecutively enrolled. As controls, 13 healthy subjects unexposed to <it>M. tuberculosis </it>(TST^-, QFT-IT^-) and 29 subjects with cured pulmonary TB were enrolled. IFN-γ whole blood response to RD1 proteins and QFT-IT were evaluated at day 1 post-culture. A prolonged test evaluating long-term IFN-γ response (7-day) to RD1 proteins in diluted whole blood was performed.</p> <p>Results</p> <p>Among the enrolled TST⁺subjects with suspected LTBI, 70/106 (66.0%) responded to QFT-IT and 64/106 (60.3%) to RD1 proteins at day 1. To evaluate whether a prolonged test could improve the detection of LTBI, we set up the test using cured TB patients (with a microbiologically diagnosed past pulmonary disease) who resulted QFT-IT-negative and healthy controls as comparator groups. Using this assay, a statistically significant difference was found between IFN-γ levels in cured TB patients compared to healthy controls (p < 0.006). Based on these data, we constructed a receiver operating characteristic (ROC) curve and we calculated a cut-off. Based on the cut-off value, we found that among the 36 enrolled TST+ subjects with suspected LTBI not responding to QFT-IT, a long term response to RD1 proteins was detected in 11 subjects (30.6%).</p> <p>Conclusion</p> <p>These results indicate that IFN-γ long-term response to <it>M. tuberculosis </it>RD1 antigens may be used to detect past infection with <it>M. tuberculosis </it>and may help to identify additional individuals with LTBI who resulted negative in the short-term tests. These data may provide useful information for improving immunodiagnostic tests for tuberculosis infection, especially in individuals at high risk for active TB.</p

Accuracy of Immunodiagnostic Tests for Active Tuberculosis Using Single and Combined Results: A Multicenter TBNET-Study

The clinical application of IFN-gamma release assays (IGRAs) has recently improved the diagnosis of latent tuberculosis infection. In a multicenter study of the Tuberculosis Network European Trialsgroup (TBNET) we aimed to ascertain in routine clinical practice the accuracy of a novel assay using selected peptides encoded in the mycobacterial genomic region of difference (RD) 1 for the diagnosis of active tuberculosis in comparison with tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (Cellestis Ltd., Carnegie, Australia) and T-SPOT.TB (Oxfordimmunotec, Abingdon, UK)

Results of anti-Toxoplasma gondii IgG, IgM, IgA and IgG Avidity testing in pregnant women in Rome, Italy

To evaluate the incidence of Toxoplasma gondii infection, the detection of specific IgG, IgM, IgA and IgG avidity was performed on 1424 pregnant women referred to the “L. Spallanzani” Hospital in Rome (Italy). Of the 1424 women screened, 20 (1.40%) were likely to have been recently infected (presence of IgM/IgA, and/or low IgG avidity), 29 (2.04%) had positive IgM coupled with high IgG avidity, 7 (0.49%) had an unspecific result for IgM alone, 1339 (94.0%), were negative for both IgG and IgM, 29 (2.04%) showed evidence of past infection (IgG positive, IgM negative, high IgG avidity). In Conclusion our results underscore the importance of efficient antenatal screening and appropriate treatment for Toxoplasma infection in Italy

Melody transcatheter pulmonary valve implantation. results from the registry of the Italian Society of Pediatric Cardiology (SICP).

Abstract BACKGROUND AND AIMS: Percutaneous implantation of pulmonary valve has been recently introduced in the clinical practice. Our aim was to analyse data of patients treated in Italy by using the Melody Medtronic valve. METHODS: Prospective, observational, multi-centric survey by means of a web-based database registry of the Italian Society of Pediatric Cardiology (SICP). RESULTS: Between October 2007 and October 2010, 63 patients were included in the registry (median age: 24 years; range 11-65 years). Forty subjects were in NYHA class I-II while 23 were in NYHA class III-IV. Patients included had a history of a median 3 previous surgeries (range 1-5) and a median of 1 previous cardiac catheterization (range 0-4). A cono-truncal disease was present in 39 patients, previous Ross operation in 9, other diagnosis in 15. Indication to valve implantation was pure stenosis in 21 patients, pure regurgitation in 12, association of stenosis and regurgitation in 30. Implantation was performed in 61 subjects (97%). Pre-stenting was performed in 85% of cases. Median procedure time was 170 minutes (range 85-360). No significant regurgitation was recorded after procedure while the trans-pulmonary gradient reduced significantly. Early major complications occurred in 7 subjects (11%). One death occurred in the early post-operative period in a severely ill subject. At a median follow-up of 30 months (range 12-48 months) three patients died due to underlying disease. Major complications occurred in 6 patients during follow-up (external electric cardioversion: 1 pt; herpes virus encephalitis: 2 pts; Melody valve endocarditis needing surgical explant: 2 pts; major fractures of the stent and need second Melody valve implantation: 2 pts). Freedom from valve failure at latest follow-up was 81.4%?9%. CONCLUSION: Early results of the SICP registry on transcatheter Melody pulmonary valve implantation show that the procedure is safe and successful. Major concerns are related to the occurrence of stent fracture and bacterial endocarditis. Longer follow-up and larger series are needed

Cardiotoxic effects of moderate acute carbon monoxide poisoning in the rabbit

The study shows that even moderate CO poisoning can produce heart damage in the rabbit as demonstrated by long lasting alterations in myocardial metabolism and acute blood levels increase of necrosis markers