Micro - Mycology (Systemic & Cutaneous Mycoses) Flashcards
Pg. 143-144 Sections include: Systemic mycoses Cutaneous mycoses
What are the systemic mycoses?
(1) Histoplasmosis (2) Blastomycosis (3) Coccidioidomycosis (4) Paracoccidioidomycosis
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?
All are caused by dimorphic fungi: cold (20 C) = mold, heat (37 C) = yeast; Exception: Coccidioidomycosis = spherule (not yeast) in tissue
What condition do all fungi associated with systemic mycoses cause? What other relevant characteristic do they all share in terms of infection?
All can cause pneumonia and can disseminate
How are the fungi that can cause systemic mycoses treated in the following contexts: (1) Local infection (2) Systemic infection?
(1) Fluconazole or Itraconazole (2) Amphotericin B
What condition can systemic mycoses mimic, and why? How is it different from that condition?
TB (granuloma formation); Unlike TB, have no person-to-person transmission
What is the endemic location for Histoplasmosis?
Mississippi and Ohio River valleys
What disease/condition does Histoplasmosis cause?
Pneumonia
Where is Histoplasma seen on on blood smear?
Macrophage filled with Histoplasma (smaller than RBC); Think: “Histo Hides (within macrophages)”
Where is Histoplasma often found (in nature)?
Bird or bat droppings
What is the endemic location for Blastomycosis?
States east of Mississippi River and Central America
What disease/condition(s) does Blastomycosis cause?
Causes inflammatory lung disease and can disseminate to skin and bone. Forms granulomatous nodules
What characterizes Blastomycosis on blood smear?
Broad-base budding (same size as RBCs); Think: “Blasto Buds (Broadly)”
What is the endemic location for Coccidioidomycosis?
Southwestern US, CA
What disease/condition(s) does Coccidioidomycosis cause?
Causes pneumonia and meningitis; can disseminate to bone and skin; San Joaquin Valley or desert (desert bumps) “valley fever”
What causes an increase in case rates of Coccidioidomycosis, and why?
After earthquakes; Spores in dust are thrown up in the air and become spherules in lungs
What is seen on blood smear in Coccidioidomycosis?
Spherule filled with endospores (much larger than RBC); Think: “Coccidio Crowds”
What causes “valley fever”? More specifically, what kind of valley fever is it?
Coccidioidomycosis; San Joaquin Valley or desert (desert bumps) “valley fever”
What is the endemic location for Paracoccidioidomycosis?
Latin America; Think: “Paracoccidio parasails with the captain’s wheel all the way to Latin America”
What is seen on blood smear in Paracoccidioidomycosis?
Budding yeast with “captain’s wheel” formation (much larger than RBC)
What is the characteristic appearance of Paracoccidioidomycosis?
Captain’s wheel; Think: “Paracoccidio parasails with the captain’s wheel all the way to Latin America”
What are the categories of cutaneous mycoses?
(1) Tinea vesicolor (2) Other tinea
What pathogen is associated with Tinea versicolor?
Caused by Malassezia furfur
What mechanism causes Tinea versicolor, and how does it present?
Degradation of lipids produces acids that damage melanocytes and cause hypopigmented and/or hyperpigmented patches
When does Tinea vesicolor occur?
In hot, humid weather
What are the treatment options for Tinea vesicolor?
Topical miconazole, Selenium sulfide (Selsun)
What kind of prep is used for Tinea versicolor visualization? How does Tinea versicolor appear on this prep?
“Spaghetti and meatball” appearance on KOH prep
Aside from Tinea versicolor, what are 5 other kinds of Tinea and the areas that they affect?
(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)
Aside from Tinea versicolor, how do other kinds of Tina present?
Pruritic lesions with central clearing resembling a ring
Again, what pathogen causes Tinea versicolor? What pathogens cause other Tinea?
Malassezia furfur; Dermatophytes (Microsporum, Trichophyton, & Epidermophyton)
Again, what is seen on KOH prep for Tinea versicolor? What is seen on KOH prep for other Tinea?
Spaghetti and meatballs appearance; See mold hyphae, not dimorphic
Name the 4 kinds of systemic mycoses and how the size of their associated pathogen compares to the size of RBCs.
(1) Histoplasmosis - smaller than RBC (2) Blastomycosis - same size as RBC (3) Coccidioidomycosis - much larger than RBC (4) Paracoccidioidomycosis - much larger than RBC
