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
What mycoses is also known by the following names:
Desert fever,
Valley fever,
San Joaquin fever
Coccidiomycosis
Coccidiomycosis pathogenesis
- Inhalation of arthroconidia
- Invasion of lung septae = growth into spherules containing endospores
- Mature endospores = nodules
- Burst nodules = caused symptoms
- Second gen - isotropic growth stage
Isotropic growth defined
Growth rates are same in all directions
Skin test - Coccidiomycosis
Delayed hypersensitivity rxn
-Similar to Tb test
Positive result: coin like lesions/ coccidioidoma (diff from Tb test result)
Risk factors - Coccidiomycosis
- Race: Filipinos > African American> Caucasian
- Age: Extremes more susceptible
- Sex: Males more susceptible
- Pregnancy
- Immunosuppression
Lab ID - Coccidiomycosis
Specimens: respiratory (sputum, bronchoscopic), biopsy tissue from site of infection, blood and CSF for serology)
Direct microscopy – presence of spherules, mature spherules with endospores
Culture – grows readily on SDA at rtp
Reduced O2 = spherules readily produced
Biopsy = calcofluor stain
Spherule + Mold phase in Coccidiomycosis
Mature spherule phase = large spherules (30-60 um)
- produces barrel-shaped arthrospores (2.5 -4x 3-6 um)
- arthrospores alternate with disjunctor cells (fungi cells undergoing lysis)
Mold phase has white colonies with septat hyphae
Serology Tests for Coccidiomycosis and signs of infection and remission based on tests
Serology tests:
Tube preciptin
Latex particle agglutination
Complement fixation assay(CSF)
Serology Is good rising titers—infection
Declining titers —remission
Cross-reaction does not occur in patients with histoplasmosis for Coccidiomycosis (T/F)
False
Treatment for Coccidiomycosis
Amphotericin B, Fluconazole
Paracoccidiomycosis
Paracocccidioides brasiliensisi
Transmission - Paracoccidiomycosis
Inhale microconidia
Symptoms - Paracoccidiomycosis
Subacute - 60% present like Tb
Fever, chills, cough, W loss
Symptoms - Paracoccidiomycosis
Subacute - 60% present like Tb
Fever, chills, cough, W loss
Additional symptom: ulcers in buccal mucosa/mouth and lymphoadenopathy (abnormal sized lymph nodes)
Differential diagnoses - Paracoccidiomycosis
Tb
Leishmania
Lab ID - Yeast and mold - Paracoccidiomycosis
Skin scrapings = yeast cells
Result - ‘Mariner’s wheel’ - Large buds radiating from central vacuole (blood agar)
Mold grows as white colonies with septate hyphae , chlamydospores and lateral unicellular conidia (SDA)
Paracoccidiomycosis - Specimens
Specimens
respiratory , aspirates, ulcerative material, biopsy tissue from site of infection, blood for serology
Serology - Paracoccidiomycosis
Test for AB
Treatment - Paracoccidiomycosis
Amphotericin B.
Mild cases - Sulphonamides
