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

Syphilis serology: Seroprevalence in a selected population and considerations on the Euroline WB test

Introduction: The clinical diagnosis of syphilis is always supported by appropriate laboratory tests and the test results are interpreted with reference to the patient’s history. In the diagnosis of syphilis, the use of tests based on antibody search that recognize both treponemal and reaginic antigens increases the diagnostic chances. Our study discusses the various serological and alternative tests currently available along with their limitations, and relates their results to the likely corresponding clinical stage of the disease. Methods: in our laboratory were analyzed 264 sera and 4 liquor (123 Females, 145 Males). 187 patients are subject at low risk for luetic infection, including pregnant woman, patient with organ transplant, outpatients or hospitalized undergoing routine serological, and 81 from patients with confirmed syphilis including 4 pregnant women in antibiotic treatment, patients with suspected disease, HIV positive and patients with autoimmune diseases with Cardiolipin positive. All sera were tested with ELISA Anti-Treponema pallidum Screen (IgG / IgM) and in parallel with agglutination tests VDRL and TPHA. On all positive sera was tested Euroline-WB EUROIMMUN and reading done with the program EuroLineScan. Results: by ELISA Anti-Treponema pallidum Screen IgG / IgM 162 sera were negative and 106 sera positive (39.5%), distributed as follows: 45 (42%) with a value greater than 200 RU / ml, 43 (41% ) with a value> 22 RU / ml and 18 (17%) with a borderline value between> 16 to <22 RU / ml. The execution of the Blot IgG showed: 18 negative sera, 6 with borderline value with one only band of specific antigens (p15, p45, p47 or p17), while 82, including 4 liquor (neurolue), were certainly positive showing more than one band antibody to the treponemal antigens. Only one patient had in place at the time of screening, an initial infection; in fact, there was a single clear positivity in the IgM protein bands, while 7 sera was uncertain values. It is reported 11 positivity for IgM Cardiolipin, while Cardiolipin IgG was detected with a high positivity in 34 sera. The presence of borderline values and / or positivity for a single protein band can be attributed to a unspecific reaction caused by autoimmune diseases or related cross-reactions with other Spirochete or to other Borrelia. Conclusions: The immunoblot test gave useful information at epidemiological and clinical level. The deepening with a confirmation test with proteic antigens and cardiolipin identifies false reactivity, but also indicates the specific reactivity to past infection and a better characteriation in the different stages of disease. In our study in the latent forms there are relevant discrepancies among the various tests. Compare to traditional methods, anti-cardiolipin antibodies positivity in our confirmatory test has the advantage of providing non subjective interpretation, being based upon the EuroLineScan program

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