Tuberculosis other diagnostic studies: Difference between revisions
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(/* Nucleic Acid Amplification Tests (NAAT) Adapted from CDC {{Cite web: url=http://www.cdc.gov/tb/publications/guidelines/amplification_tests/reccomendations.htm| title= CDC Report of an Expert Consultation on the Uses of Nucleic Acid Amplification T...) |
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====Adenosine Deaminase==== | ====Adenosine Deaminase==== | ||
====Nucleic Acid Amplification Tests (NAAT) <small><small><small> Adapted from CDC <ref name="CDC NAAT"> {{Cite web | ====Nucleic Acid Amplification Tests (NAAT) <small><small><small> Adapted from CDC <ref name="CDC NAAT"> {{Cite web| url=http://www.cdc.gov/tb/publications/guidelines/amplification_tests/reccomendations.htm| title= CDC Report of an Expert Consultation on the Uses of Nucleic Acid Amplification Tests for the Diagnosis of Tuberculosis}}</ref></small></small></small>==== | ||
*This is a heterogeneous group of tests that use p[[olymerase chain reaction]] (PCR) to detect mycobacterial nucleic acid. | *This is a heterogeneous group of tests that use p[[olymerase chain reaction]] (PCR) to detect mycobacterial nucleic acid. | ||
*These test vary in which nucleic acid sequence they detect and vary in their accuracy. | *These test vary in which nucleic acid sequence they detect and vary in their accuracy. | ||
Revision as of 21:07, 5 September 2014
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Other diagnostic studies that could be performed in a patient with tuberculosis are the Adenosine Deaminase Test and Nucleic Acid Amplification Test(NAAT).
Other Diagnostic Studies
Adenosine Deaminase
Nucleic Acid Amplification Tests (NAAT) Adapted from CDC [1]
- This is a heterogeneous group of tests that use polymerase chain reaction (PCR) to detect mycobacterial nucleic acid.
- These test vary in which nucleic acid sequence they detect and vary in their accuracy.
- The two most common commercially available tests are the amplified mycobacterium tuberculosis direct test (MTD, Gen-Probe) and Amplicor (Roche Diagnostics).
- The CDC recommends that NAA testing should be performed on a respiratory specimen from each patient with signs and symptoms of active pulmonary TB disease for whom a diagnosis of TB is being considered (i.e., TB suspect), but has not been established.
- NAA testing does not replace the need for AFB smear and culture. All current guidelines and recommendations for culture-based testing should remain in effect, especially recommended turn around times for culture and DST.
- A single positive NAA test result can support the diagnosis of TB in a patient for whom there is a reasonable index of suspicion. This result should trigger reporting to public health officials, initiation of treatment if not already started, and intensified efforts to obtain an isolate for drug susceptibility testing.
- In a patient with little suspicion of having active TB, a single positive NAA test result should be viewed with suspicion (i.e., a possible false-positive result) and interpreted in the same way as a single culture-positive result, i.e., by correlating the results with other diagnostic findings.
- A single negative NAA test result should never be used as a definitive test to exclude TB, especially in suspects with a moderate to high clinical suspicion of TB. Rather, the negative NAA test result should be used as additional information to aid in making clinical decisions to expedite a work-up for an alternative diagnosis or to prevent unnecessary use of TB treatment in suspects with a low clinical suspicion. .
- The FDA-approved NAA tests for TB have slightly less sensitivity than culture-isolation methods, and the 15% to 20% of U.S. TB cases that are reported with negative culture results may also have negative NAA test results. Thus, a negative NAA test result does not exclude the diagnosis of TB.
- Further research is needed before specific recommendations can be made on the use of NAA testing in the diagnosis of TB in children who cannot produce sputum and in the diagnosis of extrapulmonary TB, although there is much anecdotal evidence of the utility of such testing in individual cases.