India ink stain is used for visualizing the capsule of encapsulated B. anthracis and other capsulated organisms, especially the fungus Cryptococcus neoformans.
Cryptococcus neoformans are identified from blood, blood culture bottles, or cerebrospinal fluid (CSF).
Material for India ink stain procedure
Following are the materials for the procedure.
- Microscope and slid, coverslip
- India ink
India ink stain for cryptococcus procedure
- For the control, transfer a small amount of growth (1 mm ) from each control SBA plate into 0.5ml whole blood OR serum, and mix.
- For the unknown, take 100 microliters of the sample can be blood or CSF.
- Transfer 5 to 10 microliters of unknown or control to a slide. Place a cover slip on the drop.
- Add 5 to 10 microliter India ink to the edge of the coverslip.
- After the ink diffuses across, look at the cell at 100X oil immersion objective with oil drop on the top of the coverslip.
India ink stain result interpretation
Positive control: Capsule will appear as a clear zone around the cells
Negative control: No clear zone will appear.
Control for the procedure
Positive Control: Klebsiella pneumonia or clostridium neoformans use as a positive control.
Negative Control: E.coli ATCA 25922 was used as a negative control.
The control method of India ink
Perform the test with the suspension of the fresh culture of the control strain.
Control should be run each day.
Resolving an out-of-control result. Check the purity and identity of the control strain and repeat the test.