[Detection of mycobacterium tuberculosis complex using real-time polymerase chain reaction].
BACKGROUND
For the detection of Mycobacterium tuberculosis complex (MTB), PCR is known to be sensitive, specific, and rapid compared to the conventional methods of acid-fast-bacilli (AFB) smear and culture. We evaluated a new approach for MTB detection using real-time PCR.


METHODS
The specificity of real-time PCR was evaluated using 20 MTB isolates and 37 nontuberculous mycobacteria (NTM) isolates identified by AccuProbe Mycobacterium tuberculosis complex colony identification test (Gen-Probe Inc., USA) and Myco-ID (M&D, Korea). One hundred sputum specimens (50 AFB smear-positive and 50 negative specimens) were analyzed using real-time PCR and Amplicor Mycobacterium tuberculosis test (Roche, Germany). The results of real-time PCR positives (55 samples) and negatives (598 samples) were analyzed by AFB smear and culture.


RESULTS
The real-time PCR assay accurately discriminated between MTB and NTM species. Realtime PCR and Amplicor test yielded the same results in 96.0% (96/100) of the sputum specimens tested. The sensitivity and specificity of real-time PCR based on AFB culture were 97.4% and 88.5%, respectively. Of the 55 real-time PCR positive specimens, 83.6% (46/55) were culture-positive, 30.9% (17/55) were smear-positive, 52.7% (29/55) were smear-negative and culture-positive, and 14.5% (8/55) were both smear and culture-negative. Among the 598 real-time PCR negative specimens, 60 were not tested for AFB smear or culture and 10 were contaminated. Of the remaining 528 specimens, 478 (90.5%) were both smear and culture-negative and 39 (7.4%) were culture-positive.


CONCLUSIONS
For the detection of MTB, real-time PCR was sensitive and specific and comparable to conventional methods. It can be used for rapid identification of M. tuberculosis in clinical laboratories.
Chang
Ho Eun
HE
Department of Laboratory Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
Heo
Se Ran
SR
Yoo
Kwang Cheol
KC
Song
Sang Hoon
SH
Kim
Sung Han
SH
Kim
Hong Bin
HB
Park
Kyoung Un
KU
Song
Junghan
J
Lee
Jae Ho
JH
Park
Sung Sup
SS
Kim
Eui Chong
EC
D015373:Bacterial Typing Techniques; D003199:Computer Systems; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000382:microbiology*
D011933:Reagent Kits, Diagnostic