Journal of Clinical Microbiology, Jun 1995, 1435-1441, Vol 33, No. 6
JS Shah, J Liu, D Buxton, A Hendricks, L Robinson, G Radcliffe, W King, D Lane, DM Olive and JD Klinger
We report the results of a study conducted to evaluate the performance of
manual Q-Beta replicase-amplified Mycobacterium tuberculosis complex assay
compared with that of culture for detecting M. tuberculosis directly from
digested sputum pellets. A total of 261 specimens submitted to three
tuberculosis testing laboratories were analyzed. Culture and acid-fast
bacillus smear results were provided by the tuberculosis testing
laboratories. Of these 261 specimens, 34 (13% prevalence rate) were
positive for M. tuberculosis by culture. The samples were digested and
decontaminated by the testing laboratories by using their standard
digestion and decontamination procedures. An aliquot of the digested and
decontaminated pellet was sent to GENE- TRAK. The digested and
decontaminated pellet was neutralized by washing it with 0.067 M phosphate
buffer (pH 6.8), and the bacteria present in the washed pellet were heat
inactivated at 100 degrees C for 15 min. The samples were combined with
sample processing buffer containing GuSCN and were treated for 6 min in the
GENE-TRAK Sample Processing Instrument to release the nucleic acids. The
release rRNA was analyzed in a manual Q-Beta replicase assay format which
incorporates elements of sandwich hybridization, reversible target capture,
and Q-beta replicase signal amplification technologies. In comparison with
culture, the overall assay sensitivity and specificity were 97.1 and 96.5%,
respectively. The positive predictive value was 80.5%, and the negative
predictive value was 99.5%. After analysis of discrepant results, the assay
sensitivity and specificity were 97.3 and 97.8, respectively, and the
prevalence rate was 14%. The positive predictive value and the negative
predictive value were 87.8 and 99.5%, respectively.(ABSTRACT TRUNCATED AT
250 WORDS)
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Q-beta replicase-amplified assay for detection of Mycobacterium tuberculosis directly from clinical specimens
GENE-TRAK, Framingham, Massachusetts 01701, USA.
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