Diagnosis of Tuberculous Meningitis

Diagnostic Tests

• The Infectious Diseases Society of America (IDSA) guidelines state that nucleic acid amplification tests (NAAT) for M. tuberculosis in non-respiratory specimens like CSF may have poor sensitivity, with culture remaining the gold standard, having a reported sensitivity of 25-70% for diagnosing tuberculous meningitis 1
• The highest yields for AFB smear and culture occur when large volumes (≥5 mL) of CSF are used, according to the IDSA guidelines 1
• Despite advances in molecular technology, CBNAAT/PCR should always be accompanied by culture requests due to suboptimal sensitivity, as recommended by the IDSA 1
• A negative CBNAAT does not rule out tuberculous meningitis, and culture and empiric treatment should still be considered based on clinical presentation and CSF parameters, according to the IDSA guidelines 1
• Collecting ≥5 mL CSF is optimal for testing, as stated in the IDSA guidelines 1
• The IDSA recommends sending AFB smear, culture, CBNAAT, and ADA simultaneously for optimal diagnosis 1
• If clinical suspicion is high and ADA is elevated, empiric treatment should not be delayed while waiting for culture or CBNAAT results, as advised by the IDSA 1