Principle of the Germ Tube Test
This test allows the detection of the Germ Tubes which are the initial stage of hyphae formation. These are the short, non-septate germinating hyphae which are one half the width and three to four times the legnrh of the yeast from which they originate. Approximately 95-97% of Candida albicans isolate develop germ tube when incubated in a proteinaceous media at 35C for 2.5-3 hours.
- Sheep serum or pooled human serum
- Test tube
- Wooden applicator stick
- Microscopic glass slide
- Cover slip
- Pasteur pipette
Procedure of germ tube test
- Put about 0.5 ml of sheep serum or pooled human serum in a test tube
- With a sterile wooden applicator stick, lightly touch a yeast colony (1-2 large colonies or 3-4 small colonies) and then place the stick into the serum
- Suspend the yeast in serum and discard the stick
- Incubate the tube for 2-3 hours in a 35-37C incubator
- After incubation, place a drop of suspension on a clean microscopic slide and coverslip it
- Examine the wet mount microscopically using low power objective. Use high power objective to confirm the presence or absence of germ tubes.