Micro - Mycology (Systemic & Cutaneous Mycoses)

Question 1

What are the systemic mycoses?

Answer 1

(1) Histoplasmosis (2) Blastomycosis (3) Coccidioidomycosis (4) Paracoccidioidomycosis

Question 2

In general, what kind of fungi cause systemic mycoses? More specifically, define cold versus heat and the kind of fungi associated with each condition? What is the exception to these associations?

Answer 2

All are caused by dimorphic fungi: cold (20 C) = mold, heat (37 C) = yeast; Exception: Coccidioidomycosis = spherule (not yeast) in tissue

Question 3

What condition do all fungi associated with systemic mycoses cause? What other relevant characteristic do they all share in terms of infection?

Answer 3

All can cause pneumonia and can disseminate

Question 4

How are the fungi that can cause systemic mycoses treated in the following contexts: (1) Local infection (2) Systemic infection?

Answer 4

(1) Fluconazole or Itraconazole (2) Amphotericin B

Question 5

What condition can systemic mycoses mimic, and why? How is it different from that condition?

Answer 5

TB (granuloma formation); Unlike TB, have no person-to-person transmission

Question 6

What is the endemic location for Histoplasmosis?

Answer 6

Mississippi and Ohio River valleys

Question 7

What disease/condition does Histoplasmosis cause?

Answer 7

Pneumonia

Question 8

Where is Histoplasma seen on on blood smear?

Answer 8

Macrophage filled with Histoplasma (smaller than RBC); Think: “Histo Hides (within macrophages)”

Question 9

Where is Histoplasma often found (in nature)?

Answer 9

Bird or bat droppings

Question 10

What is the endemic location for Blastomycosis?

Answer 10

States east of Mississippi River and Central America

Question 11

What disease/condition(s) does Blastomycosis cause?

Answer 11

Causes inflammatory lung disease and can disseminate to skin and bone. Forms granulomatous nodules

Question 12

What characterizes Blastomycosis on blood smear?

Answer 12

Broad-base budding (same size as RBCs); Think: “Blasto Buds (Broadly)”

Question 13

What is the endemic location for Coccidioidomycosis?

Answer 13

Southwestern US, CA

Question 14

What disease/condition(s) does Coccidioidomycosis cause?

Answer 14

Causes pneumonia and meningitis; can disseminate to bone and skin; San Joaquin Valley or desert (desert bumps) “valley fever”

Question 15

What causes an increase in case rates of Coccidioidomycosis, and why?

Answer 15

After earthquakes; Spores in dust are thrown up in the air and become spherules in lungs

Question 16

What is seen on blood smear in Coccidioidomycosis?

Answer 16

Spherule filled with endospores (much larger than RBC); Think: “Coccidio Crowds”

Question 17

What causes “valley fever”? More specifically, what kind of valley fever is it?

Answer 17

Coccidioidomycosis; San Joaquin Valley or desert (desert bumps) “valley fever”

Question 18

What is the endemic location for Paracoccidioidomycosis?

Answer 18

Latin America; Think: “Paracoccidio parasails with the captain’s wheel all the way to Latin America”

Question 19

What is seen on blood smear in Paracoccidioidomycosis?

Answer 19

Budding yeast with “captain’s wheel” formation (much larger than RBC)

Question 20

What is the characteristic appearance of Paracoccidioidomycosis?

Answer 20

Captain’s wheel; Think: “Paracoccidio parasails with the captain’s wheel all the way to Latin America”

Question 21

What are the categories of cutaneous mycoses?

Answer 21

(1) Tinea vesicolor (2) Other tinea

Question 22

What pathogen is associated with Tinea versicolor?

Answer 22

Caused by Malassezia furfur

Question 23

What mechanism causes Tinea versicolor, and how does it present?

Answer 23

Degradation of lipids produces acids that damage melanocytes and cause hypopigmented and/or hyperpigmented patches

Question 24

When does Tinea vesicolor occur?

Answer 24

In hot, humid weather

Question 25

What are the treatment options for Tinea vesicolor?

Answer 25

Topical miconazole, Selenium sulfide (Selsun)

Question 26

What kind of prep is used for Tinea versicolor visualization? How does Tinea versicolor appear on this prep?

Answer 26

“Spaghetti and meatball” appearance on KOH prep

Question 27

Aside from Tinea versicolor, what are 5 other kinds of Tinea and the areas that they affect?

Answer 27

(1) Tinea pedis (foot) (2) Tinea curis (groin) (3) Tinea corporis (ringworm on body) (4) Tinea capitis (head, scalp) (5) Tinea unguium (onychomycosis = fungal infection of fingernails, on fingernails)

Question 28

Aside from Tinea versicolor, how do other kinds of Tina present?

Answer 28

Pruritic lesions with central clearing resembling a ring

Question 29

Again, what pathogen causes Tinea versicolor? What pathogens cause other Tinea?

Answer 29

Malassezia furfur; Dermatophytes (Microsporum, Trichophyton, & Epidermophyton)

Question 30

Again, what is seen on KOH prep for Tinea versicolor? What is seen on KOH prep for other Tinea?

Answer 30

Spaghetti and meatballs appearance; See mold hyphae, not dimorphic

Question 31

Name the 4 kinds of systemic mycoses and how the size of their associated pathogen compares to the size of RBCs.

Answer 31

(1) Histoplasmosis - smaller than RBC (2) Blastomycosis - same size as RBC (3) Coccidioidomycosis - much larger than RBC (4) Paracoccidioidomycosis - much larger than RBC