What is a CSF Culture?
CSF Culture (Cerebrospinal Fluid Culture) is a laboratory test which is done to identify pathogens in the central nervous system (CNS) such as in bacterial meningitis, fungal infections and other microbial invaders. CSF is a sterile fluid that is found in the sub arachnoid space surrounding the brain and spinal cord and has an important role in providing nourishment to the brain and spinal cord and in regulating the environment around these organs.
CSF culture is a very useful test in serious CNS infections since conditions such as meningitis and encephalitis are extremely dangerous if not treated early. It is used to determine the specific cause of the infection in order to provide the most appropriate treatment.
Types of Microorganisms Detected in CSF Culture
- Bacterial Pathogens: These include Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, Escherichia coli and Mycobacterium tuberculosis.
- Viral Pathogens: Enteroviruses, Herpes Simplex Virus (HSV), Varicella-Zoster Virus (VZV) and Cytomegalovirus (CMV).
- Fungal Pathogens: Cryptococcus neoformans, Candida species and Aspergillus species.
Parasitic Infections: Rare but possible including Naegleria fowleri (primary amoebic meningoencephalitis).
How is the Test Performed?
The CSF test is performed by an expert healthcare provider in a sterile environment. The patients are advised to stay hydrated and doing rest after the test to avoid the onset of headache that is a common side effect of it.
Preparation
- For the collection procedure the patient is positioned in a leaning forward while sitting position or the knees folded towards the chest.
Collection
- The test consists in drawing a sample of cerebrospinal fluid from the spine through a procedure known as lumbar puncture after administering a local anesthesia
Laboratory Analysis
- This specimen is then placed in a culture media and incubated in a controlled environment to identify bacterial, viral or fungal pathogens.
- It is then examined under a microscope
What are the symptoms that prompt this test?
General Symptoms
- Headaches
- Otorrhea drainage
- Changes in vision, taste and hearing
- Vomiting
- Nausea
- Pain in the neck
- Problem with balance
- Sensitivity to sound and light
- Behavior changes
- Seizures
What are Normal Ranges for This Test?
Analysis of CSF include various parameters, the generally accepted parameters are given below;
- Appearance – Clear or colorless
- White Blood Cells – 0 to 5 cells/mL
- Protein – 15 to 45 mg/dL
- Glucose – 50 to 80 mg/dL
- Culture Results – Negative (no bacterial, fungal, or viral growth)
**The parameters mentioned above depends on the assay of the test and vary betwee laboratories. **
What Happens if Test Results Show Abnormal Levels?
Abnormal result of CSF culture test is indicative of the following infections and conditions
- Bacterial infection
- Viral infection
- Fungal infection
- Tuberculosis meningitis
If abnormalities are diagnosed further testing is suggested such as further CSF analysis, MRI, CT scan, and other blood tests to detect the systemic infection.
