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20 Cards in this Set
- Front
- Back
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Fungi as infectious agents
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molds and yeast found in air, dust, fomites, normal flora
humans relatively resistant fungi relatively non-pathogenic n 300 species known to infect human fungi typically plant pathogen human mycoses are caused by true fungal pathogens and opportunistic pathogens |
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Mycosis
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true fungal pathogens can invade and grow in a health, non compromised host
most striking adaption to survival and growth in human host is the ability to switch from hyphal cells to yeast cells thermal dimorphism is when fungi grow as molds at 30 degrees C and yeast at 37 degrees C |
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opportunistic fungal pathogens
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fungi has little or no virulence factors, host defense must be impaired
vary from superficial and colonization to potentially fatal systemic disease emerging nosocomial infections account for 10% dermatophytes may be undergoing transformation to true pathogens |
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epidemiology of mycoses
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most fungal pathogens do not require host to complete life cycles, and most are not communicable
candida and dermatophytes naturally inhabit human body and can be transmitted true fungal pathogens are distributed in a predictable geographical pattern dermahytosis most prevalent |
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pathogenesis of fungi
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portal of entry respiratory, inhalation of spores
subcutaneous, inoculation of skin, trauma cutaneous, superficial colonization on skin virulence factors thermal dimorphism, toxic like substance, capsule, adherence, inflammatory stimulators, hydrolytic enzymes |
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host defense
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antifungals are integrity of external barriers, respiratory cilia
most important defense is, cell mediated immunity, macrophages, inflammation |
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control of mycotic infections
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immunization not effective
usually controlled by intravenous amphotericin B, azoles, flucytosine, nystatin damaged tissues surgically removed sometimes prevention limited to masks, and clothing |
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Histoplasmosis: Ohio Valley Fever
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Histoplasma capsulatum most common true pathogen, causes hstoplasmosis
dimorphic distributed world wide, mostly in central, eastern US grows in moist soil, high in nitrogen inhaled candida produce pulmonary infection, to chronic lung disease |
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coccidioidmycosis
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Coccidioides immitis cause coccidioidmycosis
distinctive morphology, block like arthroconidias in free living stage and spherules containing endospores in lungs lives in alkaline soils in semiarid hot climates, south western US inhalation of the arthroconidia creates spherules, can form nodules in lungs |
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Blastomyces dermatidis
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Blastomyces dermatidis causes blastomycosis
dimorphic free-living species in soil of Midwestern, southeastern, US. inhaled 10-10000 conidia convert to yeast and multiply in lungs symptoms cough and fever chronic cutaneous, bone, nervous system complications |
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cutaneous mycoses
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dermatophytoses are infections strictly confined to keratinized epidermis: skin, hair, nails
ringworm, tinea 39 species: trichophyton, microsporium, epidermophyton causative agent of ringworm varies case to case |
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dermatophytoses
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natural reservoirs of human, animal, water
hardiness of dermatophyte spore, abrasion of skin, intimate contact promote infection long infection period followed by localized inflammation and allergic reactions to fungal proteins. |
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tineas
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ringworm of scalp, head and hair
ringworm of beard effects chin and beard of adult males ringworm of body occurs as inflamed red ring lesions anywhere on smooth skin ringworm of groin affects groin and scrotal regions ringworm of foot and hand athlete3s foot ringworm of nails, persistent colonization of the nails |
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tineas treatment
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treatment of dermatophyte includes tropical antifungal agents for 1-2 years
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Candida albicans
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wide spread yeast infection cause of 709% nosocomial infections
found in large intestine, organs, genitalia, or skin infections can be short-lived, superficial skin irritations to overwhelmingly fatal systemic disease forms off-white patsy colony with yeasty odor |
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Candida albicans
thrush vulvovaginal cutaneous |
thrush occurs as thick, white, adherent growth on mucous membranes of mouth and throat
vulvovaginal yeast infection is a painful, inflammatory condition of female genitalia, ulceration, and discharge cutaneous infections occurs in chronically moist areas of skin and in burn patients |
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Candida albicans
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presumptive diagnosis if budding yeast and pseudohyphal cell found called a germ tube
growth in selective and differential media differentiates candida species containing corn meal typical antifungals at superficial infections |
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Cryptococcus neoformans
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Cryptococcus neoformans causes cryptococcosis
widespread encapsulated yeast that inhabits soil around pigeon roosts common infection of AIDS, cancer, or diabetic patients infection of lungs leads to cough, fever, and lung nodules dissemination to meninges and brain can cause severe neurological disturbance and death |
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Pneumocystis jiroveci
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small, unicellular, obligate, parasitic fungi causes pneumonia
serious infections in elderly, AID patients, and infants most prominent opportunistic infection in patients causing life threatening pneumonia protozoan and fungal characteristics, lacks ergosterol in its plasma membrane this pneumonia forms secretions in the lungs that block breathing and can be rapidly fatal if not controlled with medication |
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Aspergillus
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Very common airborne soil fungus
8 species involved in human disease A. fumigatus most commonly serious opportunistic threat to AIDS, leukemia, and transplant patients infection usually occurs in lungs where spores germinate and form fungal balls, can colonize in sinuses, ear canals, eyelids, and conjunctiva invasive aspergillosis can produce necrotic pneumonia, infection of brain, heart and other organs |
