301-0191 Rev. C, May 2012
1
English
In Vitro
Diagnostic Medical Device
P
ROPRIETARY
N
AME
Xpert® MTB/RIF Assay
C
OMMON
OR
U
SUAL
N
AME
Xpert MTB/RIF Assay
A.
I
NTENDED
U
SE
The Xpert MTB/RIF Assay for use with the Cepheid GeneXpert® system is a semi-quantitative,
nested real-time PCR
in-vitro
diagnostic test for the detection of:
•
Mycobacterium tuberculosis
complex DNA in sputum samples or concentrated sediments prepared
from induced or expectorated sputa that are either acid-fast bacilli (AFB) smear positive or
negative
• Rifampin-resistance associated mutations of the
rpoB
gene in samples from patients at risk for
rifampin resistance
The Xpert MTB/RIF Assay is intended for use with specimens from untreated patients for whom
there is clinical suspicion of tuberculosis (TB). Use of the Xpert MTB/RIF Assay for the detection of
M. tuberculosis
(MTB) or determination of rifampin susceptibility has not been validated for patients
who are receiving treatment for tuberculosis.
B.
S
UMMARY
AND
E
XPLANATION
Globally, about 2 billion people are infected with MTB.
1
Every year almost 9 million people develop
active disease, and 2 million people die of the illness. Active MTB, which is predominantly
pulmonary in nature, is a highly infectious airborne disease. Given the infectious nature of MTB, fast
and accurate diagnosis is an important element of MTB treatment and control.
Treatment involves prolonged administration of multiple drugs and is usually highly effective.
However, MTB strains can become resistant to one or more of the drugs, which makes cure difficult
to achieve. Four common first-line drugs used in anti-tuberculosis therapy are:
• Isoniazid (INH)
• Rifampin (RIF or Rifampicin)
• Ethambutol (EMB)
• Pyrazinimide (PZA)
RIF resistance rarely occurs in isolation and usually indicates resistance to a number of other anti-TB
drugs.
2
RIF resistance is most commonly seen in multi-drug resistant (MDR-TB) strains and has a
reported frequency of greater than 95% in such isolates.
3, 4, 5
MDR-TB is defined as a tuberculous
disease caused by a bacterial strain that is resistant to at least INH and RIF. Resistance to RIF or
other first-line drugs usually indicates the need for full susceptibility testing, including testing against
second-line agents.
