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Journal of Clinical Microbiology, 10 1995, 2582-2586, Vol 33, No. 10
KG Beavis, MB Lichty, DL Jungkind and O Giger
We evaluated the Amplicor PCR assay (Roche Molecular Systems, Branchburg,
N.J.) for direct detection of Mycobacterium tuberculosis in sputum. A total
of 532 specimens from 270 patients were decontaminated and stored at 4 or
-75 degrees C until assayed by PCR. This assay used three-step sample
preparation, biotinylated primer pairs, AmpErase, and a microtiter format
for amplicon capture and detection. Amplicor PCR results were compared with
clinical history, culture from a Lowenstein- Jensen slant, and results from
the BACTEC TB-460 system. Eighty-seven cultures from 15 patients grew M.
tuberculosis; of these, 83 (95%) were positive with the Amplicor PCR test.
The false negatives were most likely due to sample variation and
inhibitors. Of the 445 specimens from which M. tuberculosis was not
isolated, 428 (96%) were negative with the Amplicor PCR test. Of the 17 M.
tuberculosis culture-negative, Amplicor-positive specimens, 15 were
reclassified as true positives because previous cultures grew M.
tuberculosis. Of the 445 specimens which did not grow M. tuberculosis,
Mycobacterium spp. other than M. tuberculosis were isolated from 150
specimens. Three of these 150 specimens were Amplicor positive; two were
from a patient with a history of tuberculosis, and one specimen gave a
false-positive result. We do not feel that this represents
cross-reactivity, because repeated Amplicor testing of the isolate gave
negative results. The microtiter plate has 96 wells. Allowing for six
controls, 90 decontaminated specimens can be tested by one technologist in
7.5 h. This PCR assay took 7.5 h to complete and is a sensitive and
specific, rapid method for the direct detection of M. tuberculosis from
sputum.
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Evaluation of Amplicor PCR for direct detection of Mycobacterium tuberculosis from sputum specimens
Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
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