Infections Caused by Yeast and Yeast-Like Fungi

Question 1

What types of cryptococcis cause disease?

Answer 1

Neoformans and gattii

Question 2

What does crypto require for virulence?

Answer 2

Polysaccharide capsule.

Question 3

Risk factors for crypto?

Answer 3

HIV, transplant, long-term steroids, cirrhosis

Question 4

CD4 counts risk for crypto?

Answer 4

<100

Question 5

What is neoformans associated with?

Answer 5

Pigeon poop and rotting trees

Question 6

What is gatti associated with?

Answer 6

Eucalyptus in endemic areas [Candida, Pacific Northwest]

Question 7

How does cryptococcis CSF infections present?

Answer 7

1/4 to 1/3 of patients may not have typical meningeal signs and symptoms. Fever in 50%. May have lethargy and encephalopathy due to increased ICP and direct neuroinvasion. CN palsies will occur later in disease typically involving the optic nerves.

Question 8

What is a cryptococcoma

Answer 8

It is a space occupying CNS lesion.

Question 9

What are the skin lesions of crypto?

Answer 9

Looks like molluscum. May be direct innoculation or more likely disseminated.

Question 10

How does crypto effect the prostate?

Answer 10

Can cause chronic prostatitis. Usually subclinical but may serve as a reservoir leading to relapse in inadequately treated patients with disseminated crypto.

Question 11

What is the most common bone related crypto presentation?

Answer 11

Vertebral osteomyelitis

Question 12

Describe the CSF findings of crypto

Answer 12

Mild protein elevation, low to normal glucose, lymphocytic pleocytosis

Question 13

Work up of suspected crypto

Answer 13

CSF antigen and fungal culture.

Question 14

What media is needed to grow crypto?

Answer 14

Grows on most aerobic and fungal media.

Question 15

What is a method to enhance isolation of crypto from the blood?

Answer 15

Lysis centrifugation

Question 16

How is gatti and neoformans differentiated?

Answer 16

Concanavalin-glycine-thymol agar turns blue for C. gattii but not C. neoformans. Also (MALDI-TOF).

Question 17

What does H and E stain show for crypto?

Answer 17

4–10 μm yeasts which appear to have a large clearing around them because the large polysaccharide capsule does not stain.

Question 18

What do fungal stains show in crypto?

Answer 18

Narrow-based budding and variable sizes on Grocott’s methenamine silver (GMS) or periodic acid–Schiff (PAS)

Question 19

What is the purpose of a Mucicarmine stain and a Alcian blue stain?

Answer 19

Can help in the differentiation from other fungi of similar size and morphology, which lack capsules. Alcian stains the capsule blue, mucicarmine stains the capsule red.

Question 20

How is crypto antigen detected?

Answer 20

Lateral flow assay is preferred over older methods as it is more sensitive, specific and less expensive.

Question 21

Who should have routine CrAg testing? Why?

Answer 21

People with HIV with CD4 ≤100 cells/μL in countries with high incidences of cryptococcal meningitis as the antigen is positive months before signs and symptoms of disease

Question 22

What should you do if CrAg screen in an HIV patient with CD4 <100 is positive?

Answer 22

CSF examination to rule out meningitis. If active CM ruled out, pre-emptive fluconazole 400 mg PO daily × ≥12 months.

Question 23

Do CrAg titers correlate to fungal burden?

Answer 23

No. They should not be trended to monitor response as patients can stay positive years following infection.

Question 24

What is the utility of CrAG testing for pulmonary crypto?

Answer 24

It is specific but sensitivity is low.

Question 25

What are the 3 phases of treatment for crypto meningitis?

Answer 25

Induction, consolidation, maintenance.