Use of the T-spot.TB test for the diagnosis of latent tuberculosis infection

Background:Tuberculosis (TB) represents a major health problem both in developing and both in industrialized countries.The identification of individuals latently infected with Mycobacterium tuberculosis (Mtb) play a key role for the efficacy of TB control. These individuals with a latent tuberculosis infection (LTBI), especially those with high risk of reactivation (e.g. HIV + / AIDS-infected individuals, patients undergoing immunosuppressive therapy and children younger than 5 years) could benefit from a preventive treatment with isoniazid reducing the risk of progression from LTBI to active TB. Until recently, detection of LTBI has relied on the tuberculin skin test (TST), but despite the widespread use in clinical practice,TST does not reliably diagnose LTBI because several drawbacks, e.g. lacking in specificity, particularly in who were exposed to non-tuberculous mycobacteria (NTM) or were vaccinated with Bacille Calmette-Guerin (BCG) In addition, in young subjects,TST sensitivity is hampered by impaired T cell function leading frequently to false negative results.These several drawbacks limit the use of TST for the diagnose an LTBI in patients who may benefit from preventive chemotherapy. On the other hand, an accurate diagnosis of LTBI avoid the over-treatment of those patients with a positive TST results but not latently infected with Mtb. Recently, new tests based on the detection of interferon-gamma (IFN-γ) after stimulation with Mtb-specific antigens: Early secretory Antigenic Target-6 (ESAT-6) and Culture Filtrate Protein-10 (CFP-10) have been proposed for the diagnosis of active TB and LTBI. Methods: During the period from January 2009 to June 2009, in our laboratory 70 patients were tested with T-SPOT.TB (Oxford Immunotech, Abingdon, United Kingdom).We enrolled transplant patients and subjects ongoing transplant, patients immigrants from high prevalence TB countries, patients screened for immunosuppressive treatment, HIV / AIDS – infected individuals.We also tested 3 patients with clinical / radiological suspicion of active TB and 3 patients with positive tuberculin skin test and with a positive direct examination for mycobacteria in the urinary sediment. Results: In 2 patients with symptoms suggestive of TB in place,T-SPOT.TB showed a higher response of (IFN-g), more than 100 spots.Among individuals ongoing renal transplant, 6 patients tested T-SPOT.TB positive and 4 subjects were T.SPOT.TB -negative. Two patients with an autoimmune disease showed an high response to Mtb-specific antigens with T-SPOT.TB test tested before to start any treatment.T-SPOT.TB test tested strongly negative in 4 paediatric patients and in one HIV-infected individuals, regardless a positive response to a internal positive response (phytohaemagglutinin (PHA), suggesting a normal immune response. Conclusions:This preliminary data suggest that the T.SPOT.TB showed high sensitivity and specificity, producing a strongly negative response to Mtb-specific antigens in subjects who had a history of previous BCG-vaccination. In addition, T-SPOT.TB test provides, unlike the TST, indication about the potential immunosuppression of tested patient with an internal positive control that can highlight the production of IFN- γ by lymphocytes resulting in the application of this test in immunocompromised patients, e.g. children and transplantated patients and others

Discovering the coating structure of historic bowed string instruments: an analytical campaign by SR-FTIR microspectroscopy

In many cases, the possibility to analyze a micro sample from an ancient bowed string instrument allows researchers to collect a wealth of information concerning materials used by the great Masters of violin-making and their construction procedures. In fact, the stratigraphic investigation may provide important information about (i) the treatments of the wood, normally involving proteinaceous materials and inorganic fillers such as carbonates, silicates, sulphates, (ii) composition of the different superimposed layers of varnish, and (iii) organic or inorganic pigments dispersed in the binders of the different superimposed layers of varnish [1]. In the present work, a set of four micro-samples - collected from well-preserved violins made by Antonio Stradivari, Francesco Ruggeri and Lorenzo Storioni - have been mounted in cross section and investigated throughout. The analytical approach has been developed on the embedded samples by means of Synchrotron Radiation (SR) FTIR microspectroscopy in reflection mode using a 15X objective, at the Chemical and Life Sciences branch of SISSI beamline (Elettra - Sincrotrone Trieste) [2]. Data have been collected in the MIR range in correspondence of each single layer of the stratigraphy, setting the lateral resolution in order to match the layer thickness (from few microns to tens of microns). A classification model has been constructed and validated to discriminate classes of materials according to the spectral information [3]. Preliminary results obtained from measurements performed by the micro-invasive SR-FTIR approach are elaborated and discussed, together with the analytical procedures, in order to characterize the features of the different samples

Isolation of Listeria monocytogenes in a salami producing plant in Piedmont: use of pulsed field gel electrophoresis to trace contaminations

The ability of Listeria monocytogenes to survive in different environments and establish persistent contaminations is an important issue for food producers. This study aimed to assess the environmental contamination level in an Italian salami producing plant and to identify possible sources of contamination using pulsed field gel electrophoresis (PFGE) on L. monocytogenes isolates obtained from environmental (n=54) and meat samples (n=9) collected over 9 months. Detection of L. monocytogenes was performed using the UNI EN ISO 11290-1 procedure and every isolate was characterised with PFGE, using AscI and ApaI restriction enzymes. The environmental detection frequencies were constant both in the first (22%) and the second (27%) visit, thus suggesting the presence of strains adapted to the processing plant. Equipments can represent a reservoir of L. monocytogenes from which it can spread into the whole producing plant. The reservoir was documented by PFGE results which showed several persistent strains. Moreover, PFGE proved the cross-contamination between surfaces and semiprocessed products like pastes, which furthermore have been contaminated by L. monocytogenes in 100% of samples in the first two visits and in 33% in the last visit. This study gave evidence that detection methods and PFGE characterisation can be effective tools to detect possible sources and routes of contamination