Evaluation of Serological Tests for Immunodiagnosis of Pulmonary Tuberculosis using A60 and Lipoarabinomannan Antigens

M, El Kabeer; MN, Seddek; S, El Tayeb; R, El Ridi

doi:10.21608/besps.2011.36121

	Evaluation of Serological Tests for Immunodiagnosis of Pulmonary Tuberculosis using A60 and Lipoarabinomannan Antigens
Bulletin of Egyptian Society for Physiological Sciences
Article 9, Volume 31, Issue 2, June 2011, Page 125-134 PDF (195.58 K)
Document Type: Original Article
DOI: 10.21608/besps.2011.36121
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Authors
El Kabeer M^* ¹; Seddek MN¹; El Tayeb S²; El Ridi R³
¹Faculty of Science , Benha University
²Clinical Pathology Department- Faculty of Medicine Al Azhar University
³Faculty of Science, Cairo University
Abstract
Background: Problems in diagnosis of tuberculosis using smear and culture for acid fast bacilli (AFB) techniques have necessitated the exploration of the utility of serodiagnosis to support the clinical suspicion of tuberculosis. Three serological tests, namely Anti-A60 IgG enzyme-linked immunosorbent assay (ELISA), Anti-A60- IgM (ELISA) using A60 antigen and Mycodot test using lipoarabinomannan (LAM) antigen were evaluated as tools of diagnosing pulmonary tuberculosis against smear and culture methods. Materials and Methods: ELISA was used for the detection of IgG& IgM using A60 antigen, while Mycodot test was performed utilizing Lipoarabinomannan (LAM) antigen bound to plastic combs in parallel with other familiar diagnostic methods in 50 patients with pulmonary tuberculosis (Group I),25 patients with chest diseases other than tuberculosis (Group II) and 25 apparently healthy individuals(Group III) Members of (Group II) & (Group III) participate as control groups. All members of the three groups were examined for Ziehl-Neelsen (ZN) smear stains, culture for acid fast bacilli (AFB) and Tuberculin skin test. Results: ELISA IgG results were positive in 42 (84%) tuberculous patients of Group I compared to 10 (40%) non tuberculous patients in Group II and 8 (32%) individuals in Group III. ELISA IgM results were positive in 30 (60%) tuberculous patients of Group I compared to 3(12%) non-tuberculous patients of Group II and 2 (8%) individuals of Group III. Mycodot test results were positive in 33 (66%) tuberculous patients in Group I compared to 6 (24%) non-tuberculous patients in Group II and 3 (12%) individuals of Group III. The overall sensitivities and specificities of the three tests (Mycodot, IgG and IgM) were obtained on basis of the receiver operating characteristic (ROC) curve for each test and comparison of (ROC) curves of the three tests and they were (66 , 82%) for Mycodot test, (80 , 92%) for Anti-A60 IgG and (82,74%) for Anti-A60 IgM. Positive predictive values and negative predictive values were (78.57, 70.69%) for Mycodot test, (90.91, 82.14%) for IgG and (75.93, 80.43%) for IgM. Results of Ziehl-Neelsen (ZN) smear stains and culture for Acid fast Bacilli (AFB) were positive in all members of group (I), while were negative in all members of control groups { group (II) and group (III) }. Tuberculin skin tests were positive in 46(92%) tuberculous patients of group (I), 7 of 20 (35%) non-tuberculous patients and 3 of 15 (20%) individuals of group III. Conclusion: Anti A60 IgG ELISA was the best serodiagnostic technique compared with Anti 60 IgM ELISA and Mycodot test. The high diagnostic performance of Anti 60 IgG makes it a useful, Simple and rapid supporting tool to confirm the clinical judgment of tuberculosis when used as an adjunct to symptoms and signs together with other investigation tools.


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