L21/22 Flashcards
sporebearing, lack chlorophyl, have absorptive nutrition and reproduce both sexually and asexually
eukaryotic organism
Fungi range from____ forms (yeasts) to____ moulds and mushrooms
unicellular
multicellular
Yeasts and moulds
microscopic fungi consisting of solitary cells that reproduce by budding. Moulds, in contrast, occur in long filaments known as hyphae, which grow by apical extension
Moulds
occur in long filaments known as hyphae, which grow by apical extension
Yeasts
are microscopic fungi consisting of solitary cells that reproduce by budding
Heterotrophic fungi
- use reduced, preformed organic molecules as carbon source
Osmotrophic fungi
soluble nutrients are absorbed through the cytoplasmic membrane
Saprophytic - fungi
derive nutrition from degradation of dead organic matter
Dimorphic – fungi
have two different morphological form
Thermally dimorphic fungus exists in the environment in its hyphal/_____form. In the host, the change in temperature induces changes and switch to____-phase
mycelial
yeast
Dimorphic fungal pathogens are a significant cause of human disease worldwide and are known as primary_____ pathogens that cause disease in immunocompetent individuals with over 650 000 new infections occurring each year in the United States.
pulmonary
Human fungal infections
- 300 known for humans
- Superficial, cutaneous and subcutaneous mycosis are direct contact infections of the skin, hair and nails.
- Systemic mycosis - disseminate to visceral tissue
- Opportunistic mycosis - fungi with low virulence affect immunosuppressed
- Cause hypersensitivities and poisoning.
Superficial, cutaneous and subcutaneous mycoses are transmitted by___ contact
direct
dermatophytes and ringworm
The fungi involved in superficial and cutaneous mycosis are also known as this.
* disease known as tinea or ringworm
- Category for mycoses
*Scalp, beard, nack, face and arms - Piedras and tineas
Superficial mycoses
- Category for mycoses
- Hair of beard, scalp, skin, buttocks, feet, nails
- Dermatomycoses (ringworm and tineas)
Cutaneous mycoses
- Category for mycoses
- legs, feet, puncture wounds
- Sporotrichosis
Subcutaneous mycoses
The skin is composed of two distinct layers: the
epidermis - outermost
and dermis.
The outermost layer (the epidermis) is composed of layers of differentiated____. The top layer, or ______ ____, is composed of terminally differentiated, enucleated keratinocytes that are chemically crosslinked to fortify the_____ of the skin
keratinocytes
stratum corneum
barrier
Superficial mycoses
▪ invade only the stratum corneum and the superficial layers of the skin
▪ Dead tissue is invaded and there is no cellular response from the host
▪ Malassezia furfur cause tinea versicolor brownish-red scales on skin of trunk, neck, face, arms
▪ Trichosporon ssp. cause white Piedra, a superficial cosmetic fungal infection of the hair shaft
Malassezia furfur
cause tinea versicolor brownish-red scales on skin of trunk, neck, face, arms
superficial mycoses
Trichosporon ssp.
cause white Piedra, a superficial cosmetic fungal infection of the hair shaft
superficial mycoses
Cutaneous mycoses
▪ Infections of skin cells - require keratin as carbon source for growth
▪ Most com fungal diseases- humans
▪ Common genera of dermatophytes are **Microsporum and Trichophyton **
▪ Tinea corporis
ringworm of the body - circular red itchy lesions
▪ Tinea pedis
Cutaneous mycoses
athlete’s foot - scaling, fissuring, itchy lesions
▪ Tinea unguinum
Cutaneous mycoses
nail infection - nail discoloured, separates from nail bed
▪ Tinea cruris
Cutaneous mycoses
Jock itch - proximal medial thighs, genital, pubic, perineal, and
perianal skin
Cutaneous mycoses
Tinea is transmitted via the
- feet by desquamated skin scales in substrates like carpet and matting.
- Desquamated skin scales may remain infectious in the environment for months or years
Subcutaneous mycoses
▪ Caused by dermatophytes that infect under the skin
▪ Fungi normally saprophytic inhabitants of soil and decaying vegetation
▪ Introduced via puncture wound
▪ Disease develops slowly, often over years
Osmotrophic microorganisms feed by secreting extracellular ____into the environment to degrade complex polymers, such as cellulose, lignin and proteins and by transporting the resulting simple, monomeric sugars and amino acids into their own cells.
depolymerizing enzymes
Subcutaneous mycoses - Sporotrichosis caused by
Sporothrix schenckii, a dimorphic fungus (filamentous form in environment, yeast form in host)
Subcutaneous mycoses - Sporotrichosis information
▪ Caused by Sporothrix schenckii
▪ Occurs worldwide, most common in USA
▪ Found on plants – roses, hay, pine bark mulch etc.
▪ Disease is occupational hazard for florists, forestry workers
▪ Secondary spread to articular surfaces, bone and muscle is not infrequent,. Infection occasionally involve the central nervous system, lungs or genitourinary tract.
Systemic mycosis
▪ acquired by an air-borne route when spores are inhaled from the soil where the free-living fungi are found
▪ Caused by thermally dimorphic fungi: Coccidioides, Histoplasma, Blastomyces, Paracoccidioides, Emmonsia, and Emergomyces
Systemic mycosis caused by thermally dimorphic fungi:
- Coccidioides,
- Histoplasma,
- Blastomyces,
- Paracoccidioides,
- Emmonsia, and
- Emergomyces
Coccidioidomycosis
▪ Valley fever, San Joaquin fever, desert rheumatism
▪ Coccidioides (C.) immitis and Coccidioides posadasii
▪ C. immitis, primarily endemic in California, and C. posadasii, endemic elsewhere throughout the Western Hemisphere.
