Systemic Mycosis

Systemic Systemic Mycosis Mycosis Dr. Mejbah

Systemic Mycoses • Primary pathogens & opportunistic pathogens cause systemic infection. • May involve any organ or tissue of the body. • When the disease spread to several organs or tissues is referred to as disseminated.

Systemic Mycoses • Soil is the main habitat of most of these fungi. • Inhalation is the most common route of infection.

Systemic Mycoses • Systemic fungi are: Blastomyces dermatidis. Coccidiodes immitis. Histoplasma capsulatum. Paracoccidiodes brasiliensis.

Coccidiodes immitis • Invades through lungs by inhalation of athroconidia. • May widely disseminate in body • Thermally dimorphic fungus, grow as mold in soil, but yeast (spherule) in tissue.

Coccidiodes immitis • Clinical findings: • May be asymptomatic. • Symptoms are: self limiting influenza like illness – fever, malaise, cough, arthralgia, and headache. • Some patients develop hypersensitivity (erythema nodosum and rash).

Coccidiodes immitis Laboratory Identification – Spherules can be identified from sputum or tissues – Culture on Sabouraud Dextrose Agar – Serological identification by rising titer of IgG indicates dissemination.

Coccidiodes immitis

Wet mount

Histoplasma capsulatum • Dimorphic fungus, grows as hyphae in soil with bird-droppings (also bat-droppings) & as yeast in cells. • Transmitted by inhalation of airborne spores

Histoplasma capsulatum • Clinical findings: • Immunocompetent person develop self limiting influenza like illness – fever, malaise, headache, and noprodutive cough. • May disseminate to liver, spleen, bone marrow and lymph node in immunosuppressed persons.

Histoplasma capsulatum • Laboratory Identification • Yeast within macrophages in sputum or biopsy tissues • Culture on Sabouraud Dextrose Agar show hyphae at 25°C and yeast at 37°C. • Detection of antigen and antibody.

Histoplasma capsulatum

Histoplasma capsulatum inside macrophages.

Wet mount

Blastomyces dermatidis • Dimorphic fungus • Organism invades through lungs via inhalation of airborne spores, but becomes disseminated. • Disease may look like TB. • Can produce abscess.

Blastomyces dermatidis Lab Identification – Microscopy: yeast cells in sputum or biopsy specimens. – Culture on Sabourauds Dextrose Agar