Detection of Mycobacterium tuberculosis (MTB) in fecal specimens from adults diagnosed with pulmonary tuberculosis using the Xpert MTB/rifampicin test
Abstract
Background
The Xpert Mycobacterium tuberculosis (MTB)/rifampicin (RIF) is a
fully automated diagnostic test that allows for the detection of
MTB including its RIF resistance. Although the test is used for
the diagnosis of tuberculosis (TB) in sputum samples worldwide,
studies using fecal specimens are scarce. We therefore evaluated
the efficacy of the Xpert MTB/RIF test for detection of MTB in
fecal specimens obtained from adult pulmonary TB patients,
confirmed by culture and/or molecular diagnostic methods.
Methods
We conducted a retrospective case-control study to provide
proof-of-concept regarding the efficacy of the Xpert MTB/RIF
test using fecal samples for diagnosing pulmonary TB via
detection of MTB in adult patients (≥20 years) at the
Fukujuji Hospital in Tokyo, Japan.
Results
Fecal specimens were obtained from 56 active pulmonary TB
patients (including 48 sputum smear-positive and 8 sputum
smear-negative patients), 10 non-TB patients (including 4
Myocobacterium avium complex infections), and 27 healthy
individuals who were exposed to active pulmonary TB patients.
The sensitivity of the fecal Xpert MTB/RIF was 100%
(81.7%–100%) for detection of MTB in specimens from sputum
smear-positive (1+ to 3+) patients, 81.0% (58.1%–94.6%) in
specimens from sputum smear scanty positive patients, and 50.0%
(15.7%–84.3%) in specimens from sputum smear-negative
patients. Meanwhile, each of the fecal specimens from the non-TB
group was negative for MTB (specificity 100%; 95% confidence
interval, 86.2–100).
Conclusions
The fecal Xpert MTB/RIF test could detect MTB in a large proportion of smear-positive pulmonary TB patients, without frequent false-positive results at a TB referral hospital in Japan.
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Source:
Open Forum Infectious Diseases
