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21 Cards in this Set
- Front
- Back
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There are 4 true fungal pathogens. What makes them true pathogens and what are they?
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A true fungal pathogen is able to infect an immunocompetent person. The four are:
Histoplasma capsulatum (histoplasmosis) Coccidioides immitis (coccidiomycosis) Blastomyces dermatidis (blastomycosis) Paracoccidioides brasiliensis (paracoccidiomycosis) |
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What is the mechanism of histoplasma capsulatum lung infection?
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We inhale the spores (conidia)--> most are caught up in the mucous in the upper respiratory tract (that's why we rarely see fungal URTI)--> if the spores make it through the URT, they can get all the way down to the LRT--> transform into yeast and multiply
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Fungi can be dimorphic. What does this mean?
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They change between mycelia and yeast forms. The yeast form is what survives phagocytosis and can divide to cause a larger infection
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Histoplasma capsulatum is commonly found where geographically?
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Infection is common in endemic areas (Ohio, Mississippi Valley, Midwest)
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Histoplasma growth is particularly associated with what? (aka, what stimulates their growth)
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Associated with GUANO of birds (commonly Starlings), chickens (on farms) and bats (in caves and attics); they looooove the nitrogen in bird shit.
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What does histoplasmosis look like on a CT or x ray?
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granulomatous, calcifications, patchy pneumonia, 'snowstorm pattern' on CXR
even in an asymptomatic infection, can see a ton of calcifications in anyone who has ever lived in the midwest |
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What drugs treat histoplasmosis?
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itraconazole (most common anti fungal for everything), ketoconazole, amphotericin B
these drugs are for the infection, and remember 95% of people infected are asymptomatic |
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Coccidiodies immitis is commonly found where geographically?
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Southwestern US and in the desert. The spores are disseminated in the dust.
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What is the mechanism of Coccidiodies immitis infection?
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inhalation of arthrospores (these are just walled off mycelia with thick wall to survive in the desert) --> convert to a yeast form called a spherule --> in the spherule are tons of endospores (infective) --> convert back to yeast and continue cycle
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What is a virulence factor of coccidiodies immitis, specifically the spherule?
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After inhalation of the arthrospores, they convert to spherules. Those spherules are antiphagocytic.
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How would a patient infected with coccidioidies present?
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most of them are asymptomatic
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What drugs treat coccidioidies immitis infections?
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azole drugs, Amphotericin B
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Geographically, were would we mostly likely find Blastomyces dermatiditis?
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Endemic to Mississippi and Ohio River valleys, Arkansas, Great Lakes, Missouri River, St Lawrence Basin
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What is the mechanism of infection of Blastomyces dermatiditis?
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Inhalation of condida (spores) --> convert to yeast
pulmonary disease follows same pattern as Histoplasma capsulatum |
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What is the carrier for Blastomycosis?
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DOGS
not cats DOGS (it's in their drool or mud that gets on their coats) |
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Blastomycosis is very similar to Histmycosis and difficult to distinguish clinically. What is one way that we are able to?
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Histomycosis rarely disseminates to other organs. Blastomycosis frequently disseminates to the skin. So if you see cutaneous lesions, you would think Blastomycosis over Histomycosis.
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How do you treat Blastomycosis?
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Ketoconazole, Amphotericin B
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Geographically, where would you find Paracoccidiomycosis?
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limited to tropical and subtropical areas of Central and South America
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What is the hallmark of Paracoccidiomycosis over the other three true fungal pathogens?
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You will see cutaneous and mucocutaneous ulcers, especially the oral and nasal cavities!!
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What causes the symptoms seen when you are effected by blasto...?
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non-specific immune response
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if you see a snowstorm pattern on CXR what do you think it is?
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histoplamosis
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