Mycobacterium tuberculosis nucleic acid probe (qualitative, cerebrospinal fluid)
This test checks for genetic material from *Mycobacterium tuberculosis*—the bacteria responsible for tuberculosis—in your cerebrospinal fluid (CSF). It helps determine if infection has spread to the central nervous system.
["A simple test to assess potential CNS tuberculosis infection using a genetic probe."]
Key facts at a glance
- LOINC
- 42716-1
- Short code
- Mycobacterium rRNA Islt NAA+probe
- Synonyms
- Mycobacterium rRNA Islt NAA+probe
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- probe-amp-tar
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your doctor may recommend this test if you have symptoms like severe headaches, neck stiffness, fever, confusion, or neurological issues, especially if you have a known or suspected history of tuberculosis. It’s also used in cases where other tests for meningitis or brain infections are inconclusive.
How the Test Works
A small sample of your CSF is collected via a lumbar puncture (spinal tap). The lab uses a specialized probe to detect genetic material from *M. tuberculosis* if present. The result is either positive (indicating possible infection) or negative (no detectable genetic material).
What the Results Mean
A positive result suggests a high likelihood of *M. tuberculosis* in your CSF, warranting further medical evaluation, including additional tests or treatment. A negative result means no genetic material was found, but other causes of symptoms (like viral meningitis) could still be present.
Preparation and Procedure
No special preparation is needed. The procedure involves a brief spinal tap under sterile conditions. You may feel mild discomfort, but it’s usually over quickly. The sample is sent to the lab for analysis.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
TB DNA in CSF probe
Frequently asked questions
This test is critical for diagnosing tuberculosis in the brain or spinal cord, where symptoms may overlap with other serious conditions. Early detection can guide treatment decisions, including antibiotics or anti-tuberculosis medications, to prevent progression.
The probe method is highly sensitive and specific for *M. tuberculosis* DNA, but false negatives can occur if the infection is very early or if the sample is contaminated. False positives are rare.
If you have a history of bleeding disorders or take blood-thinning medications, inform your doctor before the procedure to discuss precautions.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy