Candida presentation

1. ISOLATION AND IDENTIFICATION OF YEAST FROM ORAL SWAB OF ORAL
THRUSH SUSPECTED PATIENTS
PRESENTEDBY- SANJU SAH
ST. XAVIER’S COLLEGE, MAITIGHAR, KATHMANDU
DEPARTMENT OF MICROBIOLOGY

2. OBJECTIVES
• To isolate the yeast from oral swab of oral thrush suspected patient.
• To identify the isolated yeast.

3. INTRODUCTION
• Oral thrush also known as oral candidiasis, is a yeast/fungi infection of the Candida that
develops on the mucus membrane of the mouth.
• It is most commonly caused by Candida albicans, but may also caused by Candida
glabrata, Candida tropicalis.
• The risk group for oral thrush are those who have diabetes, anaemia or HIV ,who have an
illness that cause dry mouth, who use chemotherapy, radiations or drugs to treat cancer.

4. Candida albicans
• C. albicans is an opportunistic fungus (or form of yeast), or normal part of gut flora of
human.
• Budding yeast cell, 3-6µm .
• It produces true hyphae called pseudohyphae or germ tube.
• Disease that attack immune system such as HIV, AIDS and leukemia also increase the risk
for oral thrush .

5. CONTD…
• APPEARANCE OF ORAL THRUSH
• Oral thrush in adult generally appears as thick, white or cream color deposits (spots) on
the mucus membrane of the mouth.
• The mucus may appear swollen and slightly rod, spot may be raised, there may be
discomfort or burning sensation.
• Oral thrush is sometimes divided into 3 groups based on their appearance:
a) Pseudomembranous- White or cream colour spots.
b) Erythematous- Red spot usually associated with HIV infected patients.
c) Hyperplastic- Also referred to as ̎plaque-like candidiasis” or ̎̎nodular candidiasis” due
to presence of hard solid white plague.

6. PRINCIPLE
Candida albicans is an opportunistic pathogen found in the gut of the human but sometimes
it causes growth on the lining of the buccal mucosa, tongue, hard and soft palate, inner
cheeks etc causing oral thrush. It is isolated by taking oral swab and culture on SDA and
identified by microscopic examination and germ tube test.
Formation of germ tube is associated with increased synthesis of protein and
ribonucleic acid. Germ Tube solutions contains tryptic soy broth and fetal bovine serum,
essential nutrients for protein synthesis. It is lyophilized for stability. Germ tube is one of the
virulence factors of Candida albicans. This is a rapid test for the presumptive identification
of C. albicans.

7. PROCEDURE
• The sterile cotton swab will be taken and the lesional tissue will be rubbed gently over the
oral area.
• Firstly direct microscopic examination will be performed from the specimen collected on a
swab and then cultured on SDA .
• The plates will be inoculated at 37ºC for 24-48 hours.
• On the next day colony morphology will be noted .

8. GERM TUBE TEST
• 0.5ml sheep or human serum is put into a small tube
• Using a Pasteur pipette, a colony of yeast was touched and was emulsified gently.
• The tube was then inoculated at 37ºC for 3-4 hours.
• A drop of serum was transferred to a sterile slide and examined microscopically under the
low and high power objectives.

11. INTERPRETATION

12. PRACTICAL SIGNIFICANCE
• It is useful in study purpose.
• It helps in the isolation and identification of candida causing oral thrush.
• It is useful in diagnosis and treatment of oral thrush.
PRECAUTION
• Oral swab should be taken from lesional area.
• Small inoculum should be taken, large inoculum may inhibit germ tube formation.

13. REFERENCES
• https://microbiologyinfo.com/germ-tube-test-principle-procedure-results-
interpretation-and-limitations/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205665/
• https://microbeonline.com/candida-albicans-pathogenesis-diagnosis/