Authors: Ruvandhi Nathavitharana, MD, MPH—Author; Madhukar Pai, MD, PhD—co-author and Series Editor
Number of pages: 6
Download (2018, pdf, 113kb)
Overview: Clinical presentations of extrapulmonary TB (EPTB) is diverse, leading to missed cases and delayed diagnoses. Since the diagnosis of EPTB is often compromised by the paucibacillary nature of the disease, new diagnostic tools and policies have been eagerly awaited. At long last, new tools, and new policies are here. The International Standards for TB Care (ISTC) recommends that all patients, including children, who are suspected of having EPTB, should have appropriate specimens obtained from the suspected sites of involvement for microbiological and histological exam. The World Health Organization (WHO) has endorsed the use of Xpert MTB/RIF assay (Cepheid Inc., Sunnyvale, California), a cartridge based nucleic acid amplification test (NAAT), for EPTB. Xpert MTB/RIF is now considered a central test in the work-up of EPTB, and should be used along with existing tools such as microscopy, liquid cultures (which are the most sensitive technologies for MTB detection), and histopathology (biopsy) to arrive at the final diagnosis. Xpert is particularly useful in cerebrospinal fluid samples and in lymph node and other tissues. Once diagnosed, EPTB must be treated with standardized treatment regimens, as recommended by ISTC.
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Extrapulmonary Tuberculosis: New Diagnostics and New Policies
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Question 1 of 6
1. Question
Which of the following samples is not appropriate for a case of suspected tuberculous pleural effusion?
Correct
The correct answer is (a). There is no validated blood test for pleural or any form of extrapulmonary tuberculosis. Other samples listed are useful to collect.
Incorrect
The correct answer is (a). There is no validated blood test for pleural or any form of extrapulmonary tuberculosis. Other samples listed are useful to collect.
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Question 2 of 6
2. Question
Which of the following diagnostics tests is endorsed by WHO for extrapulmonary TB?
Correct
The correct answer is (c). In 2013, WHO endorsed the use of Xpert MTB/RIF for extrapulmonary TB.
Incorrect
The correct answer is (c). In 2013, WHO endorsed the use of Xpert MTB/RIF for extrapulmonary TB.
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Question 3 of 6
3. Question
Which of the following tests are banned by the government of India:
Correct
The correct answer is (d). The Indian Government has banned the use, sale and import of all commercial serological (antibody-detection) TB tests. This includes ELISA as well as rapid antibody tests. The ban applies to domestic as well as imported serodiagnostics kits. The ban is based on a WHO policy that strongly recommends against the use of serological, antibody tests for TB) The International Standards for TB Care, and Standards for TB Care in India also discourage the use of serological TB tests.
Incorrect
The correct answer is (d). The Indian Government has banned the use, sale and import of all commercial serological (antibody-detection) TB tests. This includes ELISA as well as rapid antibody tests. The ban applies to domestic as well as imported serodiagnostics kits. The ban is based on a WHO policy that strongly recommends against the use of serological, antibody tests for TB) The International Standards for TB Care, and Standards for TB Care in India also discourage the use of serological TB tests.
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Question 4 of 6
4. Question
Interferon-gamma release assays (e.g., TB Gold) and Mantoux skin test cannot distinguish between latent infection and active (pulmonary or extrapulmonary) disease. True or False?
Correct
The correct answer is TRUE. Neither Mantoux nor TB Gold can separate latency from active TB disease. Thus, they are discouraged for active TB diagnosis.
Incorrect
The correct answer is TRUE. Neither Mantoux nor TB Gold can separate latency from active TB disease. Thus, they are discouraged for active TB diagnosis.
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Question 5 of 6
5. Question
Of the following tests, which has the highest sensitivity for TB?
Correct
The correct answer is (c). Liquid cultures have the highest sensitivity.
Incorrect
The correct answer is (c). Liquid cultures have the highest sensitivity.
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Question 6 of 6
6. Question
In which of the following specimens does Xpert MTB/RIF have the lowest sensitivity?
Correct
The correct answer is (d). Xpert does not have high sensitivity in pleural fluid samples, and therefore should not be used alone. It should be used in combination with other tests such as pleural fluid/tissue cultures and biopsy.
Incorrect
The correct answer is (d). Xpert does not have high sensitivity in pleural fluid samples, and therefore should not be used alone. It should be used in combination with other tests such as pleural fluid/tissue cultures and biopsy.
How many samples would we need for pleural fluid culture?
Ideally, one pleural fluid sample for culture and one pleural biopsy sample for culture and histopathology.
Sir, for tubercular lymphadenitis, would FNAC coupled with Mantoux or IGRA be a reasonable option in a resource limited setting to confirm a diagnosis?
For suspected TB lymphadenitis, biopsy or FNAC is necessary. The tissue should be sent for histopathology and Xpert MTB/RIF (GeneXpert) testing (liquid cultures can also be done). Mantoux or IGRA are not indicated, since many Indians are latently infected, and these tests cannot separate latency from active TB. Xpert MTB/RIF has high accuracy on lymph node tissues and are recommended by WHO.
What should be the method for proper diagnosis of spinal TB?
Biopsy is already done but not conclusive.
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