Abstract
(1) Background: Tuberculosis (TB) in humans is a serious chronic epidemic disease caused by Mycobacterium tuberculosis (M. tb). The diagnosis of TB, especially extra-pulmonary TB (EPTB), is difficult. Isolation of M. tb from culture has a low sensitivity in patients with TB and an even lower sensitivity in cases of EPTB. Although Xpert MTB/RIF assays and serological tests are more sensitive than the above tests, they still lack sensitivity for EPTB diagnosis. (2) Methods: To improve the accuracy of TB diagnosis, a Rv0222-Rv2657c-Rv1509 fusion protein based iELISA was constructed, the diagnosis of TB, pulmonary TB (PTB) and EPTB was then evaluated. Sera of 40 TB patients including 14 with PTB, 14 with EPTB and 12 with no information about the form of TB, and five pneumonia patients were investigated. (3) Results: The sensitivity of the ELISA in TB, PTB and EPTB patients was 80% (95% CI: 64.4, 90.9%), 85.7% (95% CI: 57.2, 98.2%) and 92.8% (95% CI: 66.1, 99.8%), respectively, with a specificity of 70% (95% CI: 53.5, 83.4%). Both the sensitivity and specificity with this fusion protein were higher than for CFP10/ESAT6 (used as reference antigen) fusion protein (71.4%; 95% CI: 41.9, 91.6%, and 67.5%; 95% CI: 50.9, 81.4%), respectively, in cases of EPTB. All pneumonia patients’ sera tested negative in both ELISAs. (4) Conclusion: use of these new fusion proteins as antigens in serological assays has the potential to improve the diagnosis of all forms of TB in humans, especially EPTB.
Highlights
Tuberculosis (TB) in humans remains a major health problem in developing countries and is responsible for the highest mortality globally of all infectious diseases [1]
pulmonary TB (PTB) [6,21], their use in the diagnosis of extra-pulmonary TB (EPTB) has rarely been reported to our knowledge
As use of a single dominant protein-based antigen has resulted in a poor diagnostic capacity for TB, serological assays using fusion proteins as antigens has the potential to increase the accuracy for the diagnosis of TB [24]
Summary
Tuberculosis (TB) in humans remains a major health problem in developing countries and is responsible for the highest mortality globally of all infectious diseases [1]. The diagnosis of TB, especially EPTB, remains challenging as there is no single method suitable for its diagnosis. Mycobacterium tuberculosis (M. tb), from a specimen obtained from the patient and detection of acid-fast Bacillus (AFB) in smears of sputum or tissue are two conventional methods used to diagnose tuberculosis; in all cases of TB they have a low reported sensitivity (20–60%) [3]; which is even lower for the diagnosis of [2,4]. In order to improve the sensitivity of TB diagnosis, the Xpert MTB/RIF assay wa developed in 2006, it has the disadvantage of high cost and low sensitivity o
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