C-207. Comparison of in-House PCR with Conventional Techniques, and Cobas Amplicor M. tuberculosis™ kit for the Detection of Mycobacterium tuberculosis

M. Kim, H. Lee, H. Yang, J. Suh;
Kyung Hee Univ., Seoul, REPUBLIC OF KOREA.

Background: PCR assay, introduced as a fast and sensitive diagnostic method, is useful in detecting Mycobacterium tuberculosis. The purpose of this study was to evaluate the usefulness of in-house PCR assay in the detection of Mycobacterium tuberculosis by comparing PCR results with conventional diagnostic techniques and the Cobas Amplicor M. tuberculosis™ kit. Methods: We retrospectively assessed the diagnostic yield of the in-house PCR method employed for the amplification of IS6110 sequences in 2,973 specimens. We also compared the in-house PCR with the Cobas Amplicor M. tuberculosis™ kit in 120 collected specimens from June to July 2006. Routine acid-fast stain and culture assay were also performed and analyzed. Results: Of 2,973 cases, 2,832 cases (95.3%) showed consistent results between in house PCR, acid-fast stain and culture methods. One hundred and forty one cases (4.7%) displayed inconsistent results. The sensitivities, specificities and positive and negative predictive values of each method were as follows: 77.5%, 99.7%, 95.5%, and 98.0% respectively for the PCR; 49.2%, 100%, 100%, and 95.7% respectively for the acid-fast stain method; and 80.7%, 100%, 100%, and 98.3% respectively for the culture assay. Consistent results between the PCR and the Cobas Amplicor M. tuberculosis™ kit were shown in 109 cases (90.8%). The sensitivities, specificities and positive and negative predictive values of each method were as follows: 81.3%, 98.9%, 96.3%, and 93.5% respectively for the PCR; 71.9%, 100%, 100%, and 90.7% respectively for the Cobas Amplicor™ kit. Conclusion: The in-house PCR and Cobas Amplicor™ kit shows high sensitivity and specificity and is a reliable test in the diagnosis of tuberculosis.