Systemic Mycoses
Dr.HudaThese infections result from inhalation of the spores of dimorphic fungi that have their mold forms in the soil.
Within the lungs, the spores differentiate into yeasts or other specialized forms.
Most lung infections are asymptomatic and self-limited.
However, in some persons, disseminated disease develops in which the organisms grow in other organs, cause destructive lesions, and may result in death.
Infected persons do not communicate these diseases to others.
Present in endemic area…Ohio , Missisipi.Diagnosed by skin test (delayed hypersensitivity reaction) & negative result can reflect dissemiation of disease.Serolgy ( CFT ,Radioimmunoassey) is a good method but cross reaction can occur.
Treatment & Prevention of Coccidioide
No treatment is needed in asymptomatic or mild primary infection. Amphotericin B (Fungizone) or Itraconazole is used for persisting lung lesions or disseminated disease. Ketoconazole is also effective in lung disease. Fluconazole is the drug of choice for meningitis. There are no means of prevention except avoiding travel to endemic areas.COCCIDIOIDE
HISTOPLASMABLASTOMYCES
PARACOCCIDIOIDES
Systemic Mycoses
COCCIDIOIDE
COCCIDIOIDEDisease Coccidioides immitis causes coccidioidomycosis. Properties C. immitis is a dimorphic fungus that exists as a mold in soil and as a spherule in tissue
Transmission & pathogenesis
. In soil, it forms hyphae with alternating arthrospores which is light & carried by the wind and inhaled by lung In the lungs, arthrospores form spherules that are large, have a thick, doubly refractive wall, and are filled with endospores. Upon rupture of the wall, endospores are released and differentiate to form new spherules. .Pathogenesis of Coccidioide
Asymptomatic or mild influanza like illness. Granulomatous lesions can occur in virtually any organ but are found primarily in bones and the central nervous system (meningitis) Dissemination from the lungs to other organs occurs in people who have a defect in cell-mediated immunity. 10% develop erythema nodosum or arthralgias. This syndrome is called "valley fever" or "desert rheumatism"; it tends to subside spontaneously.*
Spherules of Coccidioides immitis
Figure 22.8HISTOPLASMA
Properties of Histoplasma
H. capsulatum ,the causative agents is a dimorphic fungus that exists as a mold in soil and as a yeast in tissue. It forms two types of asexual spores (1) tuberculate macroconidia, with typical thick walls and fingerlike projections that are important in laboratory identification, (2) microconidia, which are smaller, thin, smooth walled spores that, if inhaled, transmit the infection.
Pathogenesis & Clinical Findings of Histoplasma
Inhaled spores are engulfed by macrophages and develop into yeast forms. In tissues, H. capsulatum occurs as an oval budding yeast inside macrophagesPathogenesis & Clinical Findings of Histoplasma
It grows in soil, particularly if the soil is heavily contaminated with bird dropping With intense exposure (eg, in a chicken house or bat infested cave), pneumonia may become clinically manifest. The organisms spread widely throughout the body; especially to the liver and spleen Severe disseminated histoplasmosis develops in a small minority of infected persons with a reduced cell-mediated immunity, such as AIDS patients.*
Laboratory Diagnosis of Histoplasma
Zarqa Private UniversityBiology 4223 – The Fungi Histoplasma capsulatumBLASTOMYCES
Disease of Blastomyces
Blastomyces dermatitidis causes blastomycosis, known as North American blastomycosis.Properties of Blastomyces
B. dermariridis is a dimorphic fungus that exists as a mold in soil and as a yeast in tissue. The yeast is round with a doubly refractive wall and a single broad-based budNote that this organism forms a broad-based bud, whereas Cryptococcus neoformans is a yeast that forms a narrow-based bud.
Cutaneous blastomycosis
Figure 22.6Laboratory Diagnosis of Blastomyces
In tissue biopsy specimens, thick-walled yeast cells with single broad-based buds are seen microscopically. Hyphae with small pear-shaped conidia are visible on culture. The skin test lacks specificity and has little value. Serologic tests have little value.PARACOCCIDIOIDES
Disease of ParacoccidioidesParacoccidioides brasiliensis causes paracoccidioidomycosis, also known as South American blastomycosis.
Properties of Paracoccidioides
P. brasiliensis is a dimorphic fungus that exists as a mold in soil and as a yeast in tissue. The yeast is thick walled with multiple buds, in contrast to B. derrnatitidis, which has a single bud .