Germ tube test is done in mycology laboratories ( microbilogy laboratories that are studying fungi) to determine fungal infection in medical facilities. Germ tube test is a laboratory test which has a purpose to identify a kind of yeast Candida Albicans strains.
Candida Albicans creates a germ tube when they incubated ( waiting in a certain temperature and humidity in a certain time means incubation ) in a liquid media for 3 hours. Other yeast kinds can’t form a germ tube so germ tube test helps us to distinguish candida albicans from other yeast.
How the Germ Tube Test is Done ?
1- Place 0.5 mL of human serum in a sterile tube
2- A little amount of 24 hour incubated yeast culture sample is inoculated ( adding or spreading culture sample into the culture media) in human serum
3- Incubate the germ tube culture sample in laboratory oven at 37° for 3 hours.
4- After 3 hours germ tube test sample will be ready for examination. Take a little drop on a microscope slide and analyse it under the microscope.
Germ Tube Test Results Evaluation
1- Germ tube must be the half width and 3-4 times length of yeast cell.
2- There must not be any constriction at the point of yeast cell’s origin.
3- Germ tube’s edges must be paralel to each other.
4- Germ tube must not be pieced.
After 3 hours of incubation if these signs are seen we can say that Germ Tube Test is positive (+) and the causative microorganism of yeast infection is candida albicans. If results are found negative this doesn’t exactly mean yeast is not candia albicans because % 5 of candia albicans can’t create a germ tube so some other laboratory tests must be done for exact diagnosis.