IFN-γ showed the highest sensitivity as an individual diagnostic test. When a combination of tests was used, positivity of 'either IFN-γ or real-time PCR' appeared valuable for the diagnosis of pleural TB.

Existing diagnostic tests for pleural tuberculosis (TB) have inadequate accuracy and/or turnaround time. Interferon-gamma (IFNg) has been identified in many studies as a biomarker for pleural TB. Our objective was to develop a lateral flow, immunochromatographic test (ICT) based on this biomarker and to evaluate the test in a clinical cohort. Because IFNg is commonly present in non-TB pleural effusions in low amounts, a diagnostic IFNg-threshold was first defined with an enzyme-linked immunosorbent assay (ELISA) for IFNg in samples from 38 patients with a confirmed clinical diagnosis (cut-off of 300pg/ml; 94% sensitivity and 93% specificity). The ICT was then designed; however, its achievable limit of detection (5000pg/ml) was over 10-fold higher than that of the ELISA. After several iterations in development, the prototype ICT assay for IFNg had a sensitivity of 69% (95% confidence interval (CI): 50-83) and a specificity of 94% (95% CI: 81-99%) compared to ELISA on frozen samples. Evaluation of the prototype in a prospective clinical cohort (72 patients) on fresh pleural fluid samples, in comparison to a composite reference standard (including histopathological and microbiologic test results), showed that the prototype had 65% sensitivity (95% CI: 44-83) and 89% specificity (95% CI: 74-97). Discordant results were observed in 15% of samples if testing was repeated after one freezing and thawing step. Inter-rater variability was limited (3%; 1out of 32). In conclusion, despite an iterative development and optimization process, the performance of the IFNg ICT remained lower than what could be expected from the published literature on IFNg as a biomarker in pleural fluid. Further improvements in the limit of detection of an ICT for IFNg, and possibly combination of IFNg with other biomarkers such as adenosine deaminase, are necessary for such a test to be of value in the evaluation of pleural tuberculosis.

AIMS: The purpose of this study is to evaluate the A-60 antigen-based enzyme-linked immuno sorbent assay (ELISA) test for its sensitivity, specificity, and other related statistical parameters. SETTINGS AND DESIGN: Sera from 114 healthy volunteers, 105 bacteriologically confirmed cases of pulmonary tuberculosis (PTB), 59 sera from family contacts of PTB, and 40 sera from cases of lung infections other than tuberculosis collected from September to December 2003 were used for the kit evaluation. METHODS AND MATERIALS: Enzyme-linked immuno sorbent assay test using tuberculosis A-60 antigen-based kit manufactured by Anda Biologicals, France was used for the evaluation. STATISTICAL ANALYSIS: Differences in the optical density (OD) values for immunoglobulins G (IgG), and immunoglobulins M (IgM) antibodies in various groups were studied using t-test. RESULTS: On the basis of the findings the threshold value was setup as 400 U for IgG and mean OD for sera from healthy volunteers +2SD as the threshold for IgM. The sensitivity was 80% and specificity 95.8% for the IgG antibody test. The efficiency and predictive values were also high. The sensitivity for IgM was low (28.5%) but the specificity was high (95.7%). None of the 40 nontubercular lung infection cases were positive for the IgG and IgM antibody test for A-60, whereas five and three cases of 59 family contacts of PTB were positive for IgG and IgM antibody test. The test reproducibility was good for both IgG and IgM. CONCLUSION: IgG antibody test using A-60 antigen has good sensitivity and specificity, whereas IgM antibody test had high specificity but low sensitivity. Multicentric trials suggested evaluation of the diagnostic utility of the test for the extra-PTB.

India has experienced a massive surge of COVID 19 cases and death since its appearance in January 2020. In the present cohort study, the percent positivity of non-hospitalized COVID-19 cases among male and female of different age group were analysed, during both first and second wave. A total of 1,75,739 patients, from non-hospitalised settings, were referred/walked-in to our diagnostic centre in the present cohort study between August 2020-June 2021. The collection and testing were approved by NABL, Government of India.: Of the tested samples, 40999 (39.15%) males and 28730 (40.46%) females were positive for COVID-19. The second wave (February 2021-June 2021) detected higher number of positive cases (13,922 vs 55,807, p<0.001). During the first wave (August 2020-January 2021), percent positivity was more amongst male (31.28±10.75%), but second wave recorded higher percent positivity amongst female (56.8±12.24%). Asymptomatic female cases were higher during both waves (2,769; 54.05±5.85% vs 14,166; 59.48±9.88%). The highest percent positivity was amongst older >60 years of age (37.47±16.69) in both waves and lowest amongst 18-30 years (23.17±13.86%). Fever was the predominant symptom in both waves (95%) followed by cough (70% vs 86%). Abdominal pain, nausea and chest pain were prominent in the first wave. Few reports are available from India on non-hospitalized COVID-19 patients. This study will help for developing knowledge on the role of symptomatic and asymptomatic cases in transmission of SARS-CoV-2 in Central part of India amongst non-hospitalized cases and will help for developing strategies to prepare for impending subsequent waves in disparate population groups across India.