SYSTEMIC AND OPPORTUNISTIC MYCOSES Flashcards
SYSTEMIC MYCOSES
● Blastomyces dermatitidis
● Paracoccidioides brasiliensis
● Coccidioides immitis
● Histoplasma capsulatum
Blastomyces dermatitidis causes
North American Blastomycosis
Gilchrists disease
Chicago disease
Human infection is initiated in the lungs
Blastomyces dermatitidis
Blastomyces dermatitidis can be acquired through
Inhalation of the conidia or hyphal fragments.
Blastomyces dermatitidis specimen
Specimens consist of sputum, pus, exudates, urine, and biopsies from lesions.
Blastomyces dermatitidis mold form
round or pyriform conidia
Resembling lollipops
Blastomyces dermatitidis yeast phase
Thick- walled, large yeast cells with single bud on
broad-base; broad isthmus at constriction
Show broadly attached buds on thick-walled yeast cells
Blastomyces dermatitidis wet mount
Blastomyces dermatitidis culture
Sabouraud’s agar or enriched blood agar
Treatment
○ Severe cases of blastomycosis are treated with
amphotericin B
Paracoccidioides brasiliensis
● Causes
South American Blastomycosis
Causes South American Blastomycosis
Paracoccidioides brasiliensis
Inhaled, and initial lesions occur in the lung
Paracoccidioides brasiliensis
Most patients are 30-60 years of age, and over 90% are men.
Paracoccidioides brasiliensis
Specimen for Paracoccidioides brasiliensis
Specimens consist sputum, exudates, biopsies or other material from lesions
Paracoccidioides brasiliensis
Mold phase
intercalary and terminal chlamydoconidia; few pyriform
microconidia
Paracoccidioides brasiliensis yeast phase
resembles a ship wheel or pilot wheel or mariner’s wheel
Most useful for diagnosis in Paracoccidioides brasiliensis
Serologic testing
KOH or calcofluor white
■ Yeasts are often apparent
Paracoccidioides brasiliensis
Causes Coccidioidomycosis
Coccidioides immitis
Coccidioides immitis
● Causes
Coccidioidomycosis
Coccidioides immitis acquire through
Inhalation of arthroconidia leads to a primary infection
Major biologic hazard among laboratory personnel
Coccidioides immitis
Specimen for Coccidiodes immitis
sputum
exudate from cutaneous lesions
spinal fluid
blood
urine
tissue biopsies.
Coccidioides immitis mold phase
thick-walled, barrel-shaped, rectangular arthroconidia
Coccidioides immitis yeast phase
thick-walled spherules with endospores
Coccidioides immitis
● Microscopic Examination
○ KOH or calcofluor white stain:
spherules and endospores
Coccidioides immitis culture media
Inhibitory mold agar
Sabouraud’s agar, or blood agar slants
‼️REMINDER‼️
Coccidioides immitis
Since arthroconidia are highly infectious, suspicious cultures are examined only in a biosafety cabinet.
Identification must be confirmed by detection of C. immitis
specific antigen
animal inoculation
use of a specific DNA probe
Causes Histoplasmosis
Histoplasma capsulatum
most prevalent pulmonary infection in
humans and animals
Histoplasmosis
Histoplasmosis begins at
primary and begins in the lung and eventually
invades the reticuloendothelial system.
Histoplasmosis causative agent
Histoplasma capsulatum
Histoplasma capsulatum can be acquired through
inhalation of the conidia
Histoplasma capsulatum mold form
round to pyriform microconidia
round,thick-walled knobby, tuberculated macroconidia forms
Histoplasma capsulatum Yeast phase
round to oval yeast cells; intracellular to mononuclear cells
Histoplasma capsulatum
● Microscopic Examination
Observe for small ovoid cells within macrophages
Histoplasma capsulatum fungal stains
Gomori methenamine silver, periodic
acid-Schiff or calcofluor white stain
Giemsa-stained smears of bone marrow or blood
Histoplasma capsulatum
Cultured in
rich media: glucose-cysteine blood agar at 37°C and on Sabouraud’s agar or inhibitory mold agar at 25–30°C