Cryptococcus neoformans

Question 1

Morphology

and virulence factors

Answer 1

spherical yeast (not dimorphic), about 5-10um oval/spherical with a wide capsule.

Heavy thick capsule, which gives it 5 different serotypes

These capsules repeating polysaccharide antigens are its main virulence factor, becuase they are anti-phagocytic.

Urease positive.

Melanin in its cell wall also gives it a strong negative charge and protects it from immune system.

Question 2

Habitat and transmission of C neoformans

Answer 2

Found in soil and within pigeon droppings.

By inhalation

Question 3

Diseases caused

Answer 3

In Immunocompromised, mainly in AIDS.

Pneumonia, Fever, coughing,
then disseminated disease.

Meningitis. #1 cause of fungal meningitis.

Occular lesions

Ulcerative raised skin lesions.

Question 4

Diagnosis of C neoformans

3 methods

Answer 4

Bronchial washings of the lung, and staining with:
Mucicarmine, a red stain for the capsule, or
Grocotts silver stain.

CSF puncture and stain with India ink.

Latex agglutination test for the polysaccharide capsule

Question 5

C neoformans treatment

Answer 5

Strong treatment.

Join treatment with Amphotericin B + FLUCYTOSINE

Then maintenance therapy with FLUCONAZOLE

Question 6

What does the meningitis look like on radiology?

Answer 6

Soap bubble lesions in the brain.