Opportunistic mycoses

Question 1

Candida morphology

Answer 1

Dimorphic, but primarily yeast

All except glabrata can produce pseudo and true hyphae

Question 2

Candida epidemiology

Answer 2

Commensal on every mucosal surface
Most endogenous
Albicans predominates (esp in genital, oral, and cutaneous)

Question 3

Candida immunity

Answer 3

Innate defenses, opsonized yeast, need TH1 response

Question 4

Candida presentation

Answer 4

Can cause symptomatic disease in any organ system; most commonly thrush, vulvovaginal, cutaneous (can affect scrotum)

Question 5

Candida diagnosis

Answer 5

B-D-glucan test (also for aspergillus)

Yeast and pseudohyphae cultures

Question 6

Candida treatment

Answer 6

Mucosal and cutaneous–topical nystatin or azoles

Deep seated–oral IV azole or echinocandin

Question 7

Aspergillus

Answer 7

Fumigatis, flavus, niger, terreus

Question 8

Aspergillus morphology

Answer 8

Branched septate hyphae (45 degree angle) and distinctive conidiophore (looks like old-fashioned shaving brush)

Question 9

Aspergillus pathogenesis

Answer 9

Conidia are allergenic

Sinuses and lower airways can be colonized into aspergilloma–fungus ball

Question 10

Aspergillus diagnosis

Answer 10

Serum galactomannan–80% sensitive, 90% specific

Question 11

Aspergillus treatment

Answer 11

Azoles and amphotericin B, echinocandins

Question 12

Zygomyces

Answer 12

Rhizopus, mucor

Question 13

Zygomyces morphology

Answer 13

Broad hyaline, sparsely septate coenoccytic hyphae

In tissue, hyphae are ribbon-like, aseptate or sparsely septate, and non-pigmented

Question 14

Zygomyces epidemiology

Answer 14

In soil or decaying vegetation

Acquired by inhalation, ingestion, or contamination with environmental sporangiospores

Question 15

Zygomyces presentation

Answer 15

Rhinocerebral–seen in patients with metabolic acidosis

Pulmonary–rapidly progressive bronchopneumonia

Question 16

Zygomyces diagnosis

Answer 16

Characteristic hyphae in clinical samples

Question 17

Zygomyces treatment

Answer 17

Posaconazole and amphotericin B

Question 18

Pneumocystis

Answer 18

Jiriveci (humans), carinii (rat)

Question 19

Pneumocystis morphology

Answer 19

Free trophic forms, uninuclear sporocyst, or cyst containing up to 8 intracystic bodies

Question 20

Pneumocystis epidemiology

Answer 20

One of the most common infections in HIV patients

Question 21

Pneumocystis presentation

Answer 21

Interstitial pneumonitis with mononuclear infiltrate of plasma cells; can also affect other organs

Question 22

Pneumocystis diagnosis

Answer 22

Oberve in clinical samples stained with PAS, Giemsa, toluidine blue, etc

Question 23

Pneumocystis treatment

Answer 23

Bactrim most effective

Question 24

Cryptococcus

Answer 24

Neoformans, Gattii

Question 25

Cryptococcus morphology

Answer 25

Spherical to oval yeast-like organism
Narrow-based budding
Thick EC polysaccharide capsule

Question 26

Cryptococcus epidemiology

Answer 26

Neoformans–saprophyte assoc w pigeon droppings

Gattii–trees

Question 27

Cryptococcus presentation

Answer 27

Self-limiting in healthy individuals

Meningoencephalitis in immunocompromised patients

Question 28

Cryptococcus diagnosis

Answer 28

Yeast with thick refractive capsules in samples

Test for capsular antigen, latex bead test

Question 29

Cryptococcus treatment

Answer 29

Amphotericin B and flucytosine