CSF Analysis: Introduction, Culture, Sensitivity and Possible Pathogens

CSF analysis

Introduction of CSF Analysis

As you know, Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in the brain and spinal cord. It is produced by the specialized ependymal cells in the choroid plexuses of the ventricles of the brain and absorbed in the arachnoid granulations. This fluid is useful for diagnosis when the patient is suspected of meningitis either due to bacteria, virus, parasite, or even fungal infections. A clinician draws the CSF fluid in sterile tubes by lumbar puncture and sends it to the Microbiology laboratory for investigation. Therefore CSF analysis is helpful.

 CSF Analysis for Microbial Etiological Agents Identification

A sterile tube having CSF is received for culture and sensitivity.

Now follow the procedure as below-

CSF specimen

Immediate process

Centrifuge at 3000 RPM for 20 min in a sterile  test tube

Pour supernatant back to the vial and preserve

Mix sediment

  1.  Inoculate on chocolate agar, 5%  Sheep blood agar, and MacConkey agar.
  2. Incubate MacConkey agar in BOD incubator at 370C for 24-48 hours.
  3. Resting these two plates (Chocolate agar and blood agar ) in a CO2 incubator for 24-48 hours.
  4. After completion of incubation, check the growth of the organism.


If no growth of organisms, report no growth of organism after 48 hours of incubation (fluid being sterile). If there is the growth of pathogens, perform biochemical tests and antibiotics sensitivity tests.


For example, … isolated


Ampicillin: Resistance

Ceftriaxone: Sensitive

Ciprofloxacin: Intermediate

Ofloxacin: Sensitive

Amikacin: Sensitive

Gentamycin Sensitive

Meropenem: Sensitive

Chloramphenicol:  Sensitive

Co-trimoxazole: Sensitive

Note: Antibiogram uses according to types of pathogens.

Possible pathogens depend on the age of life for CSF Analysis

Neonate:  E. coli, S. agalactiae, Listeria monocytoges, Herpes Simplex Virus (HSV)-2

< months: E. coli, S. agalactiae, L. monocytogenes

<10 years: Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, viruses

Young adults: N. meningitidis, viruses

Adult: Streptococcus pneumoniae, Neisseria meningitidis

Elderly: Streptococcus pneumoniae, Listeria monocytogenes, Coagulase Negative Staphylococci (CoNS)

AIDS patients: Cryptococcus neoformans

Note: According test ordered, you can also do India ink preparation for Cryptococcus capsule observation. similarly Gram stain, fungal culture and sensitivity, antigens detection, CSF wet mount for protozoan parasites Acanthomeba, Naegleria, and so on.

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