STEP 1 Mycology 1 Flashcards
All mycotic infections can cause _______ and have the ability to _______.
They all can cause pneumonia and can all disseminate
Mycotic infections are all caused by what type of fungi?
Dimorphic fungi
If the fungi exist/thrive at 20 degrees C they are called what? 37 degrees C?
at 20 they’re called Mold
at 37 they’re called yeast
What fungi exists as a spherule in tissue and not a yeast?
Coccidioidmycosis
Treatment for localized mycotic infections? (2 possibles)
Treatment for systemic mycotic infections? (1)
Fluconazole or itraconazole for local.
Amphotericin B for systemic
Systemic mycoses can mimic ____ because mycoses cause _____.
Systemic mycoses can mimic TB because mycoses cause granuloma formation
Even if systemic mycoses mimics TB, what does NOT happen in mycotic infections that does occur in TB?
There is no person to person transmission with mycotic infections
Histoplasmosis: Location Causes what disease state What do you see on microscopy What are the sources of histo? (2) Associated with?
Mississippi and Ohio River Valleys
Causes pneumonia
See macrophages laden with histoplasma (smaller than RBCs)
Bird or bat guano
Nickname is “Cave Disease” so spelunking probably
Blastomycosis:
Locations (2)
Causes what exactly? What can form as a result?
What is seen on microscopy
States east of the Mississippi and Central America
Causes inflammatory lung disease and can disseminate to skin and bone. Forms granulomatous nodules (everywhere)
Broad-base budding on microscopy (same size as RBCs)
What is the main difference between Histoplasmosis and blastomycosis?
Histoplasmosis mostly affects the lungs.
Blastomycosis starts in the lungs and disseminates everywhere (mostly skin, bone, lungs, and brain)
Coccidioidmycosis: Location Causes (2)? Disseminates to (2)? Cases increase after what? A coccidioidmycosis spherule is filled with what?
SW U.S. and California
Causes pneumonia and meningitis is bad enough. Can disseminate to bone and skin.
Cases increase after earthquakes–> spores are thrown up in the air, inhaled, and become SPHERULES in the lungs.
Spherules (much larger than RBCs) are filled with endospores
Paracoccidioidmycosis:
Location
What does it look like on microscopy?
Latin America
Budding yeast with “captain’s wheel” formation. Also much larger than RBCs
Mneumonic for paracoccidioidmycosis
PARAcoccidio PARAsails with the CAPTAIN’S WHEEL all the way to LATIN AMERICA…boom
Name 4 systemic mycotic infections
Histo, blasto, coccidioid, and paracoccidioid
Name the only cutaneous mycotic infection STEP 1 cares about
Tinea versicolor
Tinea versicolor:
Causative agent
Pathogenesis of the characteristic red patches
Malassezia furfur
The degradation of lipids produces acids that damage melanocytes and causes hypopigmentation and/or hyperpigmentation patches
Tinea versicolor occurs in what type of climate?
Treatment (2)
What does it look like on microscopy?
- Hot, humid, moist environments/weather
- Topical miconazole or selenium sulfide
- Looks like “spaghetti and meatballs” on microscopy
Name three dermatophytes that can cause other tinea?
What do these dermatophytes cause?
Microsporium, Trichophyton, Epidermophyton.
They cause pruritic lesions with central clearing resembling a ring.
If a KOH prep is done on dermatophytes, what is seen? What is NOT seen?
Mold hypahe is seen. They are not dimorphic
Candida, aspergillus, cryptococcus, mucor, rhizopus, pneumocystis, and sprothrix are all examples of what?
Opportunistic fungal infections
Candida causes which types of infections
Superficial or systemic fungal infections
In terms of candida, what is seen in immunocompromised patients?
Oral and esophageal thrush
Candida: what is seen in diabetics and recent antibiotic use?
Vulvovaginitis
Candida: patients wearing diapers?
Diaper rash
Candida: IV drug users?
Endocarditis
Candida: worst possibilities (2)
Disseminated candidiasis
Chronic mucocutaneous candidiasis
Candida treatment:
Vaginal (1)
Oral/esophageal (2 possible)
Systemic (3)
Vaginal: topical azole
Thrush: Fluconazole or caspofungin
Systemic: amphotericin B, fluconazole, or caspofungin
Microscopy findings in candida
- Dimorphic yeast
- Pseudohyphae
- Budding yeast
Patient population to look for invasive aspergillosis:
Immunocompromised and those with chronic granulomatous disease
You see bronchiectasis and eosinophilia in a patient with asthma (or CF). You notice “septate hyphae” that branch at 45 degrees…what do they have
Allergic bronchopulmonary aspergillosis
A patient was just treated for TB infection and the infection cleared. The granulomas remain…what may be keeping the granulomas thriving?
Aspergillomas in the lung cavities
Aflatoxins are detected in your patient’s urine. He has a history of hepatitis…what should you look for?
Some species of aspergillus produce aflatoxins which are associated with hepatocellular carcinoma
*The hepatitis bit isn’t in First Aid…I was just getting at a predisposition to HCC
Microscopy findings for aspergillus?
***Septate hyphae that branch at 45 degrees
Not dimorphic
What can cryptococcus neoformans cause: 2
- Cryptococcal meningitis
2. Cryptococcosis
What kind of yeast is cryptococcus? Dimorphic?
A heavily encapsulated yeast
Not dimorphic
Where is cryptococcus found? How is it acquired and how does it disseminate?
Found in soil and pigeon droppings.
Acquired through inhalation with hematogenous spread to the meninges
Best stain for cryptococcus neoformans?
India Ink stain dammit
Microscopy findings in cryptococcus?
“Soap bubble lesions” in the brain
Wide capsular halos and unequal budding
