A pilot study on sensitivity and specificity of QuantiFERON-TB GOLD test on newly diagnosed mycobacterium tuberculosis infection in Kelantanese population

Diagnosis of tuberculosis infection has not been simple, commonly diagnosis been made after reviewing several investigation results. Unfortunately delay in diagnosis and hence treatment has made tuberculosis infection not treated early. Therefore a new test with reliability and rapidity is requir...

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Bibliographic Details
Main Author: Adnan, Azree Syazril
Format: Thesis
Language:English
Published: 2006
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Online Access:http://eprints.usm.my/47656/1/DR.%20AZREEN%20SYAZRIL%20B.%20ADNAN-24%20pages.pdf
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Summary:Diagnosis of tuberculosis infection has not been simple, commonly diagnosis been made after reviewing several investigation results. Unfortunately delay in diagnosis and hence treatment has made tuberculosis infection not treated early. Therefore a new test with reliability and rapidity is required. This study was carried out to compare between QuantiFERON-TB GOLD test and sputum culture for the detection of active Mycobacterium tuberculosis infection. Twenty four suspected active tuberculosis infected patients enrolled in this pilot cross sectional study and each patient was required to provide sputum and 5 mls of blood. _The T-cells from the patient's, serum were stimulated in-vitro with antigens specific for M tuberculosis (ESAT -6 and CFP-10). Hence, interferon gamma, (a cytokine that is released during tuberculosis infection) was detected after the in-vitro stimulation and using the QuantiFERON-TB GOLD kit, the level was quantified via ELISA method. It was analyzed using a computer software provided by the Cellestis (Manufacturer of QuantiFERON-TB GOLD test). Simultaneously sputum samples were obtained from the same patient and cultured for M tuberculosis. The results showed that when compared to sputum Acid Fast Bacillii culture, QuantiFERON-TB GOLD assay is 94.7 % sensitive and 80% specific, positive and negative predicitive values of 94% and 80%. While the likelihood ratios were 4.73 for positive cases and 16.7 for negative cases for M tuberculosis infection. Our study suggests that QuantiFERON-TB GOLD assay is a useful diagnostic kit for diagnosis of active tuberculosis infection in our country which is endemic for M tuberculosis infection and in which most of the population had been vaccinated with BCG. The sensitivity 94.7% obtained in this study is high in comparison to other study carried out in Japan,USA and Australia in which each represents 89.5%, 91.3% and 83.3% (in pulmonary TB cases). While the specificity of 80% in this study is considered low as compared to other studies, 98.1% (Japan), 97.8% (Australia) and 99.8% (USA). The increasing numbers of reported cases and delay in diagnosis due to delay in obtaining culture results are reasons for carrying out this study. Delay in diagnosis has made tuberculosis difficult to eradicate in our country. Therefore this study will provide evidence on the usefulness of QuantiFERON-TB GOLD assay as a rapid diagnostic tool kit in diagnosing new tuberculosis cases in our country. It will provide a useful supporting diagnostic instrument to the clinician for fast and accurate result.