LABORATORY Flashcards
refer to bacteriological diagnosis to confirm TB; requires collection of the necessary specimens for testing, performing the test, and making the
diagnosis based on the results.
Primary diagnostic tools
Once a presumptive TB case is identified by symptom-based screening or by chest Xray, diagnosis through [?] must be conducted.
bacteriologic confirmation
shall be the primary diagnostic test for PTB and EPTB in adults and children.
Xpert MTB/RIF
who are at high risk for Multidrug-resisant TB (MDRTB) shall be referred for Xpert MTB/ RIF testing.
All presumptive TB patients
shall be the alternative diagnostic test if Xpert is not accessible. Unavailability of Xpert MTB/RIF test shall not be a deterrent to diagnose TB disease bacteriologically.
Smear microscopy or loop mediated TB LAMP
may be utilized to process large sample loads especially in ACF activities, but not for children, PLHIV and MDR-TB risk groups.
TB LAMP
[?], patients shall be evaluated by the health facility physician who shall decide on clinical diagnosis
based on best clinical judgment.
If bacteriologic testing is negative or not available/accessible
[?] practices and procedures, containment equipment and facilities are required for non-aerosol-producing manipulations of clinical specimens such as preparation of acid-fast smears.
Biosafety Level 2
must be conducted in a Class I or II biological safety cabinet.
All aerosol-generating activities
[?] practices, containment equipment and facilities are required for laboratory activities in the propagation and manipulation of cultures of M. tuberculosis and M. bovis.
Biosafety Level 3
for screening are rapid, sensitive molecular tests for detecting TB.
Molecular WHO-recommended rapid diagnostics (mWRD)
Currently, mWRD available in the country and will be utilized by the National Tuberculosis Control Program( NTP) are:
- Xpert MTB/RIF (Cepheid, USA)
- TB LAMP (Eiken Chemical, Japan)
- Line Probe Assay (LPA)
B. Conventional tests
- Direct Sputum Smear Microscopy (DSSM)
- Cultural method
- Biochemical tests
an automated molecular a s s a y b a s e d o n t h e
extraction and amplification of genetic material in clinical
specimens.
Xpert MTB/RIF (Cepheid, USA)
used for the rapid and direct detection of MTBC; and simultaneously detects genes that encode rifampin
resistance.
Xpert MTB/RIF (Cepheid, USA)
Specimens for Xpert MTB/RIF test and corresponding volume
Sputum
Respiratory specimen other than sputum
Non-respiratory
Spot (at time of consultation) sputum collected by expectoration
Sputum
Other [?] and [?] can only be submitted to specifically designated laboratories equipped with certified biosafety cabinets such as in TB culture laboratories.
fluid aspirates and biopsy specimens
[?] are currently not accepted specimens for Xpert MTB/RIF testing.
Blood, urine and stools
a manual molecular assay to detect MTBC based on LAMP (loop-mediated isothermal amplification) techniques, a unique temperature-independent technique for amplifying DNA. It requires less than 1 hour to perform and can be read with the naked eye under ultraviolet light.
TB LAMP (Eiken Chemical, Japan)
can replace smear microscopy, especially in remote areas.
TB LAMP (Eiken Chemical, Japan)
it cannot detect rifampicin resistance and there is limited evidence of performance in comparison to Xpert MTB/RIF in children and people living with HIV (PLHIV) who have more smear negative pulmonary TB.
TB LAMP (Eiken Chemical, Japan)
It is family of DNA stripbased tests that determine the drug resistance profile of a MTBC through the pattern
of binding of amplicons ( D N A a m p l i f i c a t i o n
p r o d u c t s ) t o p r o b e s targeting the most common r e s i s t a n c e a s s o c i a t e d mutations to first- and second-line agents.
Line Probe Assay (LPA)
It is used for rapid detection o f d r u g r e s i s t a n c e t o rifampicin and isoniazid.
Line Probe Assay (LPA)