Download VII. Fungal Diseases

VII. Fungal Diseases
A.
B.
C.
D.
Basic Properties of the Fungi
Candidiasis
Dermatomycoses
Respiratory Fungal Infections
VII. A. Basic Properties of the Fungi
• Cellular Structure
– Eukaryotic Cells
– Fungal Cell Wall Structure
• Chitin
• Cellulose
– Heterotrophic Metabolism
• Decomposers
• Some parasitic species
VII. A. Basic Properties of the Fungi
• Cell Arrangement
– Molds & Fleshy Fungi
• Hyphae
• Septate & nonseptate hyphae
• Mycelium
– Yeasts
– Dimorphic fungi
VII. A. Basic Properties of the Fungi
• Classification of the Fungi
– By Reproductive Structures
– Oomycetes
• Water Molds
• Motile sexual spores
• Example: Potato blight Phytophthora
VII. A. Basic Properties of the Fungi
• Classification of the Fungi (cont.)
– Zygomycetes
• Unenclosed zygospores produced at ends of
hyphae
• Example: Black bread mold Rhizopus
– Ascomycetes
• Ascospores are enclosed in asci (sac-like
structures) at the ends of hyphae or yeasts
• Examples: Penicillium, Saccharomyces
VII. A. Basic Properties of the Fungi
• Classification of the Fungi (cont.)
– Basidiomycetes
• Basidiospores are produced on a club-shaped
structure called a basidium
• Example: Mushrooms, Cryptococcus
– Deuteromycetes
• “Imperfect fungi”
• No sexual stage is known for these fungi
• Many parasitic fungi fall into this class
• Examples: Candida, Epidermophyton
VII. B. Candidiasis
• Cause: Candida albicans
– Dimorphic fungus of the class
Deuteromycetes
– Grows as yeast or pseudohyphae
– Spread by contact; often part of normal flora
– Opportunistic infections common
– Vulvovaginitis
– Oral candidiasis (thrush)
– Intestinal candidiasis
VII. C. Dermatomycoses
• Cause: Several genera of dermatophytic
fungi
– Trichophyton, an ascomycete
– Microsporum, an ascomycete
– Epidermophyton, a deuteromycete
– Grow on skin, hair, nails
– Transmitted by contact with infected persons
or animals
VII. C. Dermatomycoses
• Tinea infections: Red, scaly or blister-like
lesions; often a raised red ring; “ringworm”
– Tinea pedis
– Tinea corporis
– Tinea capitis
– Tinea favosa
– Tinea barbae
– Tinea cruris
– Tinea unguium
VII. D. Respiratory Fungal Infections
• Cryptococcosis
– Cryptococcus neoformans
– A yeast of class Basidiomycetes
– Soil; esp. contaminated with bird droppings
– Airborne to humans
– Gelatinous capsules resist phagocytosis
– Respiratory tract infections
– Occasional systemic infections involving
brain & meninges
VII. D. Respiratory Fungal Infections
• Histoplasmosis
– Histoplasma capsulatum, an ascomycete
– Airborne infection
– Transmitted by inhalation of spores in
contaminated spores
– Associated with chicken & bat droppings
– Respiratory tract symptoms; fever, headache,
cough, chest pains
VII. D. Respiratory Fungal Infections
• Blastomycosis
– Blastomyces dermatitidis, an ascomycete
– Associated with dusty soil & bird droppings
– Skin transmission: via cuts & abrasions
– Raised, wart-like lesions
– Airborne transmission: via inhalation of
spores
– Respiratory tract symptoms
– Occasional internal infections with high
fatality rate