TB Test Diagnostic Approaches 3

Question 1

In extrapulmonary TB, which diagnostic approach is most reliable for confirming TB lymphadenitis?

Accepted Answer

Fine needle aspiration cytology (FNAC) with culture

Answer

FNAC of the affected lymph node with smear, culture, and histology provides direct microbiological and pathological evidence for confirming TB lymphadenitis.

Question 2

Which characteristic CSF finding is most consistent with tuberculous meningitis?

Accepted Answer

Lymphocytic pleocytosis with elevated protein and low glucose

Answer

TB meningitis classically presents with CSF lymphocytic pleocytosis, elevated protein, and low glucose due to meningeal inflammation and impaired glucose transport.

Question 3

What is the primary advantage of using liquid culture media (MGIT) over solid Lowenstein-Jensen media for TB diagnosis?

Accepted Answer

Faster detection time (1-3 weeks vs. 3-8 weeks)

Answer

Liquid culture systems like MGIT detect mycobacterial growth in 1-3 weeks compared to 3-8 weeks for solid media, significantly reducing time to diagnosis and treatment.

Question 4

A healthcare worker tests TST-negative on initial screening. Under the two-step protocol, a repeat TST 2 weeks later measures 12mm. This is best interpreted as:

Accepted Answer

Boosting effect of waned prior immunity

Answer

A positive result on a second TST shortly after a negative first test in a person with prior TB exposure represents boosting of previously waned delayed hypersensitivity, not new infection.

Question 5

Which molecular test is recommended by WHO as the initial diagnostic test for presumptive TB due to its simultaneous detection of M. tuberculosis and rifampicin resistance?

Accepted Answer

Xpert MTB/RIF (GeneXpert)

Answer

Xpert MTB/RIF is WHO-endorsed as the preferred initial diagnostic test as it simultaneously detects M. tuberculosis DNA and rifampicin resistance mutations within 2 hours.

(TB Test) Tuberculosis Test Certification Practice Test

(TB Test) Tuberculosis Test Certification Practice Test

TB Test Diagnostic Approaches 3