Performance of the BD ProbeTec ET direct detection assay for the analysis of Mycobacterium tuberculosis in respiratory and non-respiratory clinical specimens
الخلاصة
Early detection of Mycobacterial tuberculosis
infection (MTB) is pivotal for the treatment of tuberculosis
(TB).
Background: This study was performed to evaluate the
performance of BD ProbeTec ET direct detection assay
(DTB) against the gold standard culture technique for
confirmation of MTB infection.
Methods: A total of 266 consecutive and non-duplicate
clinical specimens for detection of MTB were included
in this study. There were 118 respiratory and 148 nonrespiratory
samples. All samples were tested by microscopy
for acid-fast bacillus (AFB), MTB culture and
biochemical identification with simultaneous testing by
DTB.
Results: A total of 88 samples (33%) were culturepositive
for MTB including 39/118 respiratory, 29/99
fluid and 20/49 tissue samples. DTB sensitivity for
respiratory samples was 97% and specificity was 96%
with a positive predictive value (PPV) of 93% and
negative predictive value (NPV) of 99%. Sensitivity of
DTB in fluid samples was 80%, specificity 88%, PPV
69% and NPV 93% whereas sensitivity of DTB for tissue
samples was 25%, specificity 90%, PPV 63% and NPV
63%. Of the 50 (56.8%) smear-positive samples, DTB
sensitivity was 100% for respiratory, 85% for fluid and
100% for tissue samples.
Conclusion: DTB performed within acceptable limits for
the rapid detection of MTB in respiratory samples
compared to fluid and tissue specimens.