Microbiology Exam 4 (Mycology-Fungi, Yeasts, Molds) – Flashcards
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Fungi have cell walls made of
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Chitin or cellulose
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Fungi cell walls do not have ______ in their cell walls
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Peptidoglycan
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Because fungi do not have peptidoglycan in their cell walls, _______ or other beta-lactam drugs can not be used to treat fungal infections
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Penicillin/other beta-lactams
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Fungi are
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Eukaryotic
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Fungi cell membranes contain
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Ergosterol
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Fungi include
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Molds, yeasts, and higher fungi (mushrooms)
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Live on dead organic matter
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Saprophytes
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Yeasts are _____ and ________
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Unicellular; facultative anaerobes
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Yeasts are ______ than bacteria
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Bigger
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Yeasts reproduce by
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Budding
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A string of yeasts that forms due to incomplete budding
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Pseudohyphae
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Yeast that is used to make breads and beer
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Saccharamyces
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Yeast that is normal flora on the skin but can cause vaginal yeast infections and thrush
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Candida
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Molds are ______ and _____
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Multicellular; aerobic
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Molds have ______ hyphae
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Branching
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A lot of mold hyphae
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Mycelium
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Vegetative mycelium (molds) are for
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Nutrition
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Reproductive mycelium (molds) form
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Spores
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What are yeasts' main portal of entry?
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Usually contact but may be inhaled
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What are molds main portal of entry?
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Inhalation of spores (or inoculation)
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What are the only two fungi that are communicable (able to catch from someone else)
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Candida and Dermatophytes (Tinea)
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Some yeasts and molds produce
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Toxins
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_______ to yeasts and molds is seldom protective
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Antibody response
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In fungal and yeast infections, ______ is very important
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Cell-mediated immunity
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Are there vaccines for fungal or yeast infections?
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No
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_______ fungal infections are localized to skin and hair; often have no immune response
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Superficial
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_______ fungal infections are those such as athlete's foot, nail bed infections, ring worm, and dermatophytes
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Cutaneous
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______ fungal infections are found under the skin, in the lymphatics; often associated with punctures or lesions
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Subcutaneous
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______ fungal infections are deep infections of internal organs
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Systemic
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______ fungal infections are sen in immunocompromised patients
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Opportunistic
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A patient may not even be aware of a ______ fungal infection because there is no cellular response and little pathology
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Superficial
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Superficial fungal infection that affects the chest, abdomen, neck, etc.
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Tinea versicolor
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Superficial fungal infection that causes discoloration of the skin (palms of hands/soles of feet)
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Tinea nigra
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Superficial fungal infection that affects the hair shaft
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Tinea piedra
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Superficial fungal infection that affects the skin and mucous membranes
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Thrush
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Superficial fungal infections respond well to
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Topical anti-fungals
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Is tinea a genus?
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No
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Invade only the superficial layers of skin, hair, and nails (cutaneous)
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Dermatophytes (Ringworm-Tinea)
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What are the (3) geneses of dermatophytes that affect the superficial layers of skin, hair, or nails?
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1) Trichophyton 2) Microsporum 3) Epidermophyton
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Cutaneous tinea (ringworm) infections are
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Communicable
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Infection caused by dermatophytes that affects the scalp
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Tinea captitis
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Infection caused by dermatophytes that affects the beard
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Tinea barbae
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Infection caused by dermatophytes that causes athlete's foot
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Tinea pedis
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Infection caused by dermatophytes that causes jock itch
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Tinea cruris
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Infection caused by dermatophytes that causes nail bed infections
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Tinea unguim
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Subcutaneous fungal infections are mostly seen in
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Tropical countries
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What is an example of a subcutaneous fungal infection?
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Sporothrix schenckii
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A subcutaneous fungal infection that is often seen in florists, farmers, and gardeners; causes ulcerative lesions and infected lymph nodes
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Sporothrix schenckii
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_______ fungal infections are caused by soil fungi and caused by inhalation of spores
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Systemic
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Systemic fungal infections invade the
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Lungs, GI tract, or blood
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Systemic fungal infections can be
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Lethal
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What are the (4) primary pathogenic fungi?
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1) Histoplasmosis 2) Blastomycosis 3) Coccidiomycosis 4) Paracoccidiomycosis
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People become infected with pathogenic fungi by
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Inhalation of spores
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What does it mean for a fungus to be dimorphic?
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It can either take the form of a mold or a yeast
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Histoplasma capsulata is a _______ fungus
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Dimorphic
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How is Histoplasma capsulata dimorphic?
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Mold grows in the soil and inhaled spores convert to yeast in host
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Histoplasma capsulata primarily infects the
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Lungs
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Infections of histoplasma capsulata resemble
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TB
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Where is blastomyces dermatitis found?
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Southeastern US (except Florida)
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Where does blastomyces dermatitidis grow?
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Soil, rotting wood, bird droppings
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How do people become infected with blastomyces dermatitidis?
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Inhalation of spores
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Blastomyces dermatitis usually cause
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Localized or disseminated infections
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Coccidioides immitis (fungus) causes
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Valley Fever
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Where is coccidioides immitis found?
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Western and Southeastern US
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How do people become infected with coccidioides immitis/how do people get Valley Fever?
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Inhalation of spores
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Coccidioides immitis causes a
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Self limiting upper respiratory disease (Valley Fever); however, some develop disseminated disease which can be fatal
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Where is paracoccidioides brasiliensis (fungus) found?
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South America
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Where does paracoccidioides brasilensis (fungus) grow?
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In soil
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The site of infection for Paracoccidioides brasiliensis is the
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Oral mucous membranes and the lungs
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The site of infection for coccidioides immitis (Valley Fever) is
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Upper respiratory tract
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The site of infection for blastomyces dermatitidis is
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The skin or bone
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The site of infection for histoplasma capsulata is
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The lungs
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Opportunistic fungi cause disease in compromised patients such as
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1) Immunosuppressed patients 2) Patients with metabolic defects 3) Surgery patients
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What are some examples of opportunistic fungi?
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1) Aspergillosis 2) Cryptococcosis 3) Zygomycosis 4) Systemic candidiasis
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Where is aspergillus fumigates found?
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Everywhere (decaying vegetation)
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What diseases does aspergillus fumigates cause in previously healthy individuals?
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Wound infections and sinus/ear infections
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What diseases does aspergillus fumigates cause in immunosuppressed individuals?
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Pneumonia and systemic infections
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A yeast with a thick carbohydrate capsule that infects spinal fluids
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Cryptococcus neoformans
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Where is cryptococcus neoformans found?
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In nature, mostly associated with pigeon feces
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How do people become infected with cryptococcus neoformans?
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Inhalation of fungal particles
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What does crytococcus neoformans cause in immunosuppressed patients?
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Subacute/chronic meningitis
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Where are zygomycosis (mucor) found?
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In the environment (soil, water, organic debris, food)
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What underlying condition is common with an opportunistic infection of zygomycosis (mucor)?
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Uncontrolled diabetes
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Zygomycosis usually invades the _______ and the _____ and is often fatal
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Lungs, brain
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How are zygomycosis infections treated?
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They are very heard to treat and are resistant to most anti-fungals
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Where is candida albicans (yeast) found?
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Normal flora (skin)
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In healthy individuals, candida albicans causes
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Oral and vaginal thrush
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Oral and vaginal thrush caused by candida albicans are
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Communicable
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In immunocompromised individuals, candida albicans causes
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Infections of the GI tract, urinary tract, or blood; problems from indwelling catheters and IV's; life threatening systemic infections
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Pneumocystis carinii is an
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Intracellular parasite
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Where is pneumocystis carinii found?
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Wild and domestic animals
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What does pneumocystis carinii cause in immunosuppressed patients?
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Insidious pneumonia
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Pneumocystis carinii infections are an important cause of death in _______ patients
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AIDS
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_______ can be developed from fungi growing in damp, poorly ventilated basements, old houses, and grain silos
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Respiratory allergies and Farmer's Lungs
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Mushroom poisoning is very bad for the
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Liver
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Found on peanuts and other grains; one of the most potent toxins known
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Aflatoxin
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How can fungal infections be diagnosed?
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1) History and clinical signs 2) Wood's lamp (for hair) 3) KOH prep 4) Tissue biopsy 5) Culture (selective media) 6) Skin tests 7) Antibody titers
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What are the (4) target sites for treatment of fungal infections?
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1) Cell membrane (ergosterol) 2) Cell wall (chitin) 3) Nucleic acid synthesis 4) Target site selection (kertatinized tissue)
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Which drugs interfere with fungal cell membrane permeability (ergosterol)?
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Nystatin and Amphotericin B (AMPHOTERRIBLE)
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Which drugs block ergosterol synthesis in fungal infections?
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Azole drugs (Itraconazole, fluconazole, ketoconazole, micoazole, clotrimazole)
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What is the nucleic acid analogue that is used to treat a limited number of fungal infections?
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5-FC
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What are the (2) anti-fungals that target chitin synthesis (not widely used in the US)?
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1) Polyoxin D 2) Nikkomycin
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Which drug is selectively incorporated into keratin containing tissues such as skin, hair, and nails and interferes with dermatophyte cell division?
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Griseofulvin
