CSF Culture and Sensitivity

Function

The Cerebrospinal Fluid (CSF) Culture and Sensitivity (C/S) test is a critical diagnostic tool used to identify the presence of pathogenic microorganisms, such as bacteria, fungi, or viruses, within the central nervous system. The CSF acts as a protective cushion for the brain and spinal cord, and it is normally sterile. When an infection occurs, pathogens breach the blood-brain barrier, leading to serious inflammation.

Why it is Ordered

This test is primarily ordered when a patient presents with symptoms of meningitis or encephalitis. Symptoms often include:

• Severe headache and sudden high fever
• Nuchal rigidity (stiff neck)
• Altered mental status or confusion
• Photophobia (sensitivity to light)
• Seizures or unexplained lethargy

Associated Conditions

The most common conditions detected via CSF culture include:

• Bacterial Meningitis: Caused by organisms like Neisseria meningitidis, Streptococcus pneumoniae, or Haemophilus influenzae. This is a medical emergency.
• Fungal Meningitis: Often seen in immunocompromised patients (e.g., Cryptococcus).
• Brain Abscess: Localized infections that may leak pathogens into the CSF space.
• Viral Encephalitis: While cultures specifically look for bacteria/fungi, the lack of growth alongside high white cell counts may suggest a viral etiology.

Identifying the specific organism through culture allows clinicians to perform 'sensitivity' testing, which determines which antibiotics or antifungals will most effectively kill the specific strain of pathogen involved, ensuring targeted and effective treatment.