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BACKGROUND: This paper aims to explore the application value of tuberculosis-specific enzyme-linked immunospot assay (T-SPOT.TB) in the diagnosis of tuberculosis. METHODS: Fifty one patients with tuberculosis (TB) admitted to Wuxi No.5 People's Hospital, Wuxi, China from June 2015 to June 2017 were selected as the TB group, and 40 patients without tuberculosis admitted in the same period were randomly selected as the non-TB group. Patients in the two groups received T-SPOT.TB, TB antibody (TB-Ab) test and mycobacterium TB deoxyribonucleic acid (TB-DNA) test, and the results were compared. RESULTS: Comparisons of the sensitivity of the three methods showed that the sensitivity of T-SPOT.TB was the highest, followed by TB-DNA from sputum samples, and that of TB-Ab was the lowest. The specificity of TB-Ab was the highest, followed by T-SPOT.TB, and that of TB-DNA from sputum samples was the lowest. In the receiver operating characteristic (ROC) curve analysis, the area under curve (AUC) of T-SPOT.TB (0.896) was the highest, followed by TB-DNA from sputum samples (0.772), and that of sputum smears (0.698) was the lowest. CONCLUSION: T-SPOT.TB can quickly and accurately determine the presence of tuberculosis infection, and it is a non-invasive examination, which can further assist in the diagnosis and guide the treatment.
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Objective This study aims to explore the application value of tuberculosis T lymphocytes enzyme-linked immune SPOT test (T-SPOT.TB) on early diagnosis of tuberculosis.Methods The TB infection in 189 inpatients suspected tuberculosis in pneumology department of Shaanxi Provincial People's Hospital was detected with T-SPOT.TB,fluorescence RQPCR,tuberculosis (TB-Ab)protein chip and PPD methods.Results The sensitivity of four methods was 91.54％ (119/130),73.85％(96/130),63.08％(82/130) and 57.69％ (75/130) respectively and the specificity of those was 89.83％ (53/59),86.44％(51/59),67.79％(40/59) and 66.10％(39/59),respectively.The sensitivity of T-SPOT.TB method was statistically higher than those of other three tests,respectively (P＜0.05).The specificity of T-SPOT.TB was significantly higher than those of TB-AB and PPD (P＜0.05),but there was no statistical difference between RQ-PCR and T-SPOT.TB (P＞0.05).The positive predictive values of T-SPOT.TB,fluorescent quantitative PCR,TB-Ab and PPD assays were 95.2％ (119/1250),92.3％ (96/104),81.2％ (82/101) and 78.9％ (75/95) respectively while the negative predictive values of those were 82.8％ (53/64),60％ (51/85),45.5％ (40/88) and 41.5％ (39/94),respectively.The false-positive rates (misdiagnosis rate) of four assays were 10.2％ (6/59),13.6％ (8/59),32.2％ (19/59) and 33.9％ (20/59) respectively and the false-negative rates (rates of missed diagnosis) of those were 8.5％ (11/130),26.2％ (34/130),36.9％ (48/130)and 42.3 ％ (55/130),respectively.The negative likelihood ratios of T SPOT.TB,fluorescent quantitative PCR,TB-Ab and PPD assays were 0.11,0.16,0.48 and 0.51 respectively,meanwhile the positive likelihood ratios of T-SPOT.TB,fluorescent quantitative PCR,TB-Ab andPPD assays were 9.0,5.4,2.0 and 1.7,respectively.What' s more,the diagnostic accordance rates of the four assays were 91.0％ (172 189),77.8％ (147 189).64.6％ (122/189) and 60.3％ (114/189),respectively.Conclusion T-SPOT.TB test is a more sensitive and specific method and of great significance to the early diagnosis of TB,which has more clinical value in different stages of tuberculosis diagnosis.
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OBJECTIVE: Multidrug-resistant tuberculosis (MDR-TB) is caused by Mycobacterium tuberculosis strains that do not respond to isoniazid and rifampicin, the two most effective first-line anti-TB drugs. Here, we designed and produced antibodies based on biomarkers that exist only in MDR-TB. METHODS: Bacilli were cultured for 4weeks at 37°C, and protein extraction was performed by sequential extraction. Bacterial cells were sonicated, centrifuged at 5000rpm for 45min, and the supernatant was collected and subjected to multiple rounds of treatment to prior to protein isolation. Protein concentration was determined using the Bradford method, and extracted proteins (50µg) from each strain (drug-sensitive- and MDR-TB isolates) were visualized on polyacrylamide gels (5-15%) with Coomassie Brilliant Blue R-250 staining. Three extracts were mixed and dialyzed against 0.1M ammonium bicarbonate (pH 8.0), followed by mass spectrometry. Specific polyclonal antibodies against purified MDR-TB proteins were purified by affinity chromatography and prepared in rabbits using three booster injections. The ELIZA test was performed for evaluation the antibody production. The antibody was treated with normal oral flora to remove any non specificity and cross reactivity. Analyses of different protein patterns (drug-sensitive- and MDR-TB) were performed by western blot. RESULTS: Our revealed that the MDR-TB strains contained specific antigens, and that the protein profiles of drug-sensitive TB strains differed from those of the MDR-TB isolates. Five bands from the MDR-TB fractions were detected as diagnostic antigens and were not observed in drug-sensitive-TB fractions. Western blot results showed that the MDR-TB antigenic fractions showed immunogenic bands at 50.0kDa and 70.0kDa, with the five antigenic MDR-TB-specific bands were identified as Rv3248c, Rv0350, Rv0440, Rv0475, and Rv3588c. CONCLUSION: Western blot data revealed dynamic properties of antibody responses that led to actionable findings for further research. Moreover, specific anti-mycobacterial antibodies, such as MDR-TB antibodies, can be essential tools in the identification of species-restricted antigens, such as drug-resistant TB antigens. The MDR-TB antibodies described here might promote identification of mycobacterial antigens during the course of infection, which could be helpful for the development of newer TB-vaccine candidates or therapeutic agents for improved TB treatment or diagnosis.
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Objective To evaluate the clinical application of the whole blood interferon γ(IFN-γ) release assay of QuantiFERON TB Gold in tube (QFT-GIT) in diagnosis of tuberculosis. Methods From October 2014 to October 2015, 109 patients with tuberculosis (45 cases of confirmed patients and 64 cases of clinically diagnosed patients) and 70 patients with non-tuberculosis were enrolled in Tianjin Medical University General Hospital. In order to evaluate diagnosis value between two kinds of tests, and to compare the differences between two groups, QFT-GIT test and colloidal gold anti tuberculosis antibody (TB-Ab) were employed to detect in two groups of patients. The ROC curve of IFN-γrelease quantity was analyzed in two groups. Results The sensitivity and specificity of QFT-GIT were 93.58% and 85.71% respectively. The positive rate was significantly higher in QFT-GIT than that of TB-Ab (χ2=43.68,P<0.01). The sensitivity of combined detection of the two methods decreased to 52.3% (57/109), but the specificity increased to 90.0% (63/70). The release quantity of IFN-γwas significantly higher in tuberculosis group than that in the non-tuberculosis group (U=330,P<0.05). The area under the ROC curve of IFN-γrelease quantity was 0.913 (95%CI:0.864-0.963). Conclusion The whole blood IFN-γrelease assay of QFT-GIT is a sensitive and specific assay for detecting tuberculosis infection. The combination QFT-GIT with TB-Ab can improve the specificity further, which could be a useful tool for the diagnosis of tuberculosis .
