Comparison of various microbiological tests including polymerase chain reaction for the diagnosis of osteoarticular tuberculosis.

PURPOSE To evaluate the utility of the polymerase chain reaction (PCR) test for diagnosing osteoarticular tuberculosis (TB). METHODS Clinical samples (synovial tissue and synovial fluid) obtained from 23 cases of suspected osteoarticular tuberculosis were subjected to Ziehl Neelsen (ZN) smear examination, radiometric BACTEC culture and PCR test for tuberculosis by amplifying 65 kDa antigen coding region of Mycobacterium tuberculosis (M.tb) genome. RESULTS PCR test was found to be much sensitive than the ZN smear examination and BACTEC culture (p<0.05) in the diagnosis of osteoarticular TB. In synovial fluid samples, PCR was positive in 73.9%, ZN smear examination in 17.39% and BACTEC culture in 39.13% of cases. The positivities were relatively lower with synovial tissue samples, the corresponding figures being 60.8, 8.6 and 26.08% respectively. Moreover, on combining the results of synovial fluid and tissues, the corresponding figures further increased to 78.2, 21.7 and 43.3% respectively. Further, sensitivity and specificity for PCR employing BACTEC culture as the "gold standard" was 100% respectively. Using BACTEC culture, the earliest positivity was seen in three days using synovial tissue specimen and 13 days with synovial fluid, the average detection times being 23.2 days and 32.6 days respectively. On the other hand, PCR test gave a positive result within 24 hours. CONCLUSIONS PCR test was shown to be much more sensitive than ZN smear examination and BACTEC culture test for diagnosing osteoarticular tuberculosis.