CSF For Gram Stain

• Overview:

What is this test?

This laboratory test is performed on a Cerebrospinal fluid sample to detect the presence and identify bacteria and fungi. This test helps the doctor in classifying bacteria grown in culture for starting the appropriate treatment.

Why is this test performed?

This test is performed:

1. To identify the cause of bacterial or sometimes fungal infection
2. To identify the shape and class of bacteria i.e. gram positive or gram-negative.

• Your doctor will ask you to change into a hospital gown and lie on your side with your spine curled forward and your knees drawn up to your chest
• The doctor or nurse will clean the injection site area on your back with a sterile solution and numb the site of injection with an anesthetic
• Lumbar puncture: The doctor will insert a needle in your lower back and collect the required amount of Cerebrospinal fluid sample
• The injection site is cleaned with a sterile solution and bandage is applied
• The fluid sample is sent to the laboratory for analysis.

1. What is gram-staining?

Gram-staining is a method of staining used in microbiology to detect the presence and identify the general type of bacteria or sometimes fungi in a sample taken from the site of a suspected infection; to generally classify bacteria grown in culture so that further identification tests can be performed and appropriate treatment given

2. What is cerebrospinal fluid?

Cerebrospinal fluid is a colorless liquid the bathes the brain and spinal cord. It plays a very important role in cushioning the central nervous system. It also provides nutrients to the spine and eliminates waste products.

3. How to prepare for this test?

Empty your bladder and bowel before the test. Inform your doctor about your completed medical history, especially of medicine such as blood-thinners and allergies.

4. What are the risks of this test?

• Bleeding
• Infection
• Damage to spinal cord nerves
• Headache after the test
• CSF leakage from injection site
• Allergic reaction to anesthetic.

5. Is the procedure painful?

No, a numbing medicine is used to make it a painless procedure. However, pressure is felt from the needle.

Positive or negative

Interpretation of test results:

1. Negative: A negative test result means that either the infection is not caused by bacteria or the bacteria are very less in number to be seen on gram-stain
2. Positive: A positive test result provides the following details about the bacteria:

• Gram-negative or positive
• Shape and size
• Presence of red or white blood cells
• Presence of bacteria inside cells.

WHY GET TESTED?

A gram stain is typically ordered along with a culture when a bacterial or sometimes fungal infection is suspected. A CSF gram stain looks for microorganisms. It is ordered when a doctor suspects meningitis or encephalitis.