A 4-year-old boy presents with low-grade fever, irritability and neck rigidity for 10 days. CSF shows lymphocytic pleocytosis, protein 150 mg/dL and glucose 35 mg/dL. Which is the most appropriate initial diagnostic test on the CSF sample?
- A Ziehl-Neelsen stain for acid-fast bacilli
- B Lowenstein-Jensen culture reported after 8 weeks
- C CBNAAT (Xpert MTB/RIF Ultra) ✓
- D Adenosine deaminase level
Correct answer: C. CBNAAT (Xpert MTB/RIF Ultra)
Explanation
Under NTEP, cartridge-based nucleic acid amplification test is the recommended initial diagnostic test for extrapulmonary specimens including CSF in suspected tuberculous meningitis, because it gives rapid results and detects rifampicin resistance. Ziehl-Neelsen staining of CSF has very poor sensitivity, culture takes weeks and delays treatment, and adenosine deaminase is nonspecific and cannot confirm the diagnosis or provide susceptibility data.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.