Comparison of in-house PCR with conventional techniques and Cobas Amplicor M. tuberculosis kit for detection of Mycobacterium tuberculosis.
OBJECTIVE
Polymerase chain reaction (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 Cobas Amplicor M. tuberculosis kit.


METHODS
We retrospectively assessed the diagnostic yield of in-house PCR method employed for the amplification IS6110 sequences in 2,973 specimens. We also compared in-house PCR with Cobas Amplicor M. tuberculosis kit in 120 specimens collected from June to July 2006. Routine acid-fast stain (AFS) 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, AFS and culture methods, whereas 141 (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 PCR; 49.2%, 100%, 100%, and 95.7%, respectively, for AFS method; and 80.7%, 100%, 100%, and 98.3%, respectively, for culture assay. Consistent results between PCR and 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 PCR and 71.9%, 100%, 100%, and 90.7%, respectively, for Cobas Amplicor kit.


CONCLUSIONS
In-house PCR and Cobas Amplicor kit show high sensitivity and specificity, and are reliable tests in the diagnosis of tuberculosis.
Kim
Myeong-Hee
MH
Department of Laboratory Medicine, Kyung Hee University College of Medicine, Seoul, Korea.
Yang
Hee-Young
HY
Suh
Jin-Tae
JT
Lee
Hee Joo
HJ
D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity