Evaluation of molecular tests in diagnosis of osteoarticular tuberculosis

Abstract

Osteoarticular tuberculosis is a relatively uncommon type of extrapulmonary tuberculosis. It is an important cause of mortality and morbidity and accounts for approximately 10-15% of all extrapulmonary forms of tuberculosis. The diagnosis is difficult and hence often late. The disability resulting from osteoarticular tuberculosis is directly related to the time of detection of disease and initiation of treatment. A prospective study of 36 patients suspected with osteoarticular tuberculosis was done from August 2010 to December 2012 was done at St. stephens hospital Delhi. For the purpose of this study, a diagnosis of osteoarticular TB was based on a combination of suggestive clinical features, in conjunction with typical radiological findings associated with osteoarticular TB. The specimens were subjected to ZN staining, Real Time PCR, Bac-T alert culture & Accuprobe. The sensitivity of real time PCR was 100%, specificity was 58.8%, positive predictive value was 73%, negative predictive value was 100%, efficiency was 80.5% considering culture as gold standard. As shown by the study, each diagnostic test including Real time PCR has its own disadvantages and shortcomings and does not provide 100% accuracy in diagnosing osteoarticular tuberculosis, therefore, strong clinical suspicion and correlation along with radiological and laboratory evidence is a must in establishing a diagnosis.