Résumé
Background: Diagnosis of Mycobacterium tuberculosis infection is still a problem in Indonesia. Bacterial culture as the gold standard takes time while acid fast staining has a low sensitivity
Objectives: To develop and assess the diagnostic potential of an ELISA-based test using monoclonal antibodies specific for 20 kDa protein of M. tuberculosis as an alternative for rapid diagnosis of tuberculosis through sputum
Materials and Methods: One hundred sputum samples were collected from suspected pulmonary TB cases using clinical and radiological findings. All specimens were examined with Lowenstein Jensen culture, acid fast staining and polymerase chain reaction. To determine the positive cut-off point for ELISA, samples from 20 tuberculosis patients and 20 healthy controls were used. Diagnostic value was determined on the sensitivity, specificity, positive and negative predictive value using bacterial culture as the gold standard
Results: Positive cut-off value was determined at optical density 0.233. Out of 100 samples tested, 72 were positive by culture. The ELISA method using monoclonal antibodies against the 20 kDa protein had a kappa value, sensitivity and specificity of 54.4%, 81% and 79%, respectively. Kappa for ELISA was better compared to acid-fast staining [51.3%] but poorer than polymerase chain reaction [64.5%]. Sensitivity was higher compared to acid-fast staining [65%] but lower than the polymerase chain reaction [92%] and specificity was better than polymerase chain reaction [71%]. Acid-fast staining had the highest specificity [100%]
Conclusion: ELISA based monoclonal antibodies against 20 kDa protein had the potential for being used as a diagnostic method for M. tuberculosis in sputum sample