Fungi Classification (Systemic) Flashcards
Primary systemic mycoses are different from other mycoses in the foll ways
- No risk factors needed to occur
- Etiology = dimorphic fungi
- Begin as respiratory illness -> disseminate to sites of body if not cured
- Symptoms = usually flu signs i.e. cough, fever, chest pain
Systemic mycosis transmission
Inhalation of fungal elements in dust
4 types of systemic mycoses
Histoplasmosis (most like Tb) - smallest size
Blastomycosis - equal size to 3rd in list
Coccidiomycosis - equal size to 2nd in list
Paracoccidiomyosis - largest size
Similarities between all systemic mycoses
- All inhaled
- All can cause pneumonia + dissemination to skin + bone
- All mimic Tb in chronic cases
- All inhaled forms are microconidia
- All treated with Azoles/Amp B if disseminated
- All stained with methylamine silver
List systemic mycoses in order of size
Histoplasmosis
Blastomycosis
Coccidiomycosis
Paracoccidiomyosis
Histoplasmosis transmission
Inhalation of spores in bird/bat droppings
Histoplasmosis symptoms
Acute - Asymptomatic/flu like/ Atypical pneumonia
Chronic - mimics Tb – weight loss, cough with hemoptysis
Define - Granuloma, caseating granuloma, necrosis
Granuloma - collection of macrophages due to inflammation.
Caseating granuloma - necrosis involving dead cells with no nuclei and debris.
Necrosis = tissue death – due to lack of blood supply
Differentiation of Tb and Histoplasmosis
Caseating granuloma mostly in upper lobe - like Tb
Difference on X-Ray:
- Buckshot calcifications (many calcified nodules) - Histoplasmosis
- one primary focus - Tb
Function of RES
Eticuloendothelial system (RES) removes immune complexes from the circulation in healthy persons.
Immunocompromised patients’ response to Histoplasmosis
No cell mediated response = no granuloma formed to contain fungi
Travels via blood and hits cells of RES
Lab ID - Histoplasma
Serum/urine - PCR
Acid fast - to rule out TB
Varieties of Histoplasma
H. capsulatum. Var capsulatum - small (2-3 x 3-4 um) oval yeast cells - classic
H. cap. Var. duboisii - large yeast cells (7-5 um)
Histoplasmosis is rarely disseminated (T/F)
True; mostly occurs in immunocompromised/ with underlying lung issues
Histoplasmosis specimen
Respiratory, biopsy tissue of affected site, blood , bone marrow
Histoplasmosis culture features
Media: SDA, BHI-A Slow growth - weeks White colonies, septate hyphae 2 types of conidia: Tuberculated macroconidia Smooth Microconidia
Blastomycosis etiology
Blastomyces dermatitidis
- Inhalation of microconidia spores in dead/decaying trees/bush
- –Can’t be cultured from soil
Blastomycosis symptoms
Acute - rare; after massive exposure
Presents with lung inflammation
- fever, tachypnea, hypoxemia
Subacute (60% cases)- resembles bacterial pneumonia
- high fever, chills, productive cough
Chronic - Mimics Tb
- night sweats, W loss, cough
Immunocompromised - Disseminated lesions (pulmonary form disseminates to skin)
Blastomycosis - Lab ID
Gold std - Ag test - PCR
Specimen - blood + urine
yeast-extract-phosphate agar
Lung biopsy - Broad Based Budding –> Broad –base attachment of bud to mother cell (yeast)
White with septate hyphae and lateral unicellular conidia (mould)
Skin tests also possible
Serological tests - Blastomycosis
antigen - yeast culture filtrate
Immunodifussion test
Complement Fixation test
cross-reaction occurs in patients having coccidiodomycosis or histoplasmosis
Treatment - Blastomycosis
Amp B - Drug of choice for rapid progression cases
Ketoconazole - less severe cases
Coccidiomycosis - etiology
Coccidiodes immitis
-Found in desert areas, hot, dry
Coccidiomycosis - transmission
Grows in the soil, but inhalation of a single spore can initiate infection.
Coccidiomycosis -
Grows as mycelia in the cold, spherules in the heat
