01 Fungus Intro Duncan Flashcards
What are viruses that attack bacteria called?
Bacteriophages
What are the characteristics of Archaea?
Bacteria-like in some respects (size, lack of nuclear membrane); Eukaryote-like in others (DNA and protein structure)
What is the Fungal Cell Wall primarily made out of?
Chitin. Hence, insensitive to inhibitors of peptidoglycan synthesis (i.e. B-Lactams)
What is an important part of the Fungal Cell Membrane?
Ergosterol. Imparts sensitivity to inhibitors of ergosterol synthesis, activity (e.g. Amphotericin, Azoles, etc.)
What are the different Fungal Growth Types?
Yeasts (single cells). Molds - mat of filaments (Mycelium, Hyphae - septate and nonseptate). Dimorphic (Shifts d/t growth situation; e.g. temperature)
What is the difference between septate and nonseptate in fungal growth types?
When looking at septate fungus, you can clearly see the different cells connected together. In Nonseptate, cell membranes between cells are dissolved
How does Fungal Reproduction occur?
Asexual (budding, conidia). Sexual (mating)
What is Fungal metabolism like?
Cannot photosynthesize; therefore must obtain carbon food from the environment
What is Chitin made from?
A long change of N-Acetylglucosamine
If the Fungal cell wall and cell membrane, what ratio varies with species?
Ratio of Chitin to branched B-Glucan
What are some Fungal Toxins and Mycotoxicoses?
Amantin (Amanita mushrooms). Ergot Alkaloids (Grain-infecting fungi (Claviceps), neurotoxicity). Aflatoxin (Aspergillus flavus growth on soiled grains, hepatotoxicity/hepatic cancer)
What is used for Fungal Diagnosis?
Microscopic examination (KOH, special stains). Culture (Sabouraud’s agar (no bacterial growth)). DNA-based tests. Serologic tests
What are the worst Fungal Diseases?
Systemic infections. Opportunistic infections
What are the causative fungi for opportunistic infections?
Cryptococcus. Candida. Aspergillus. Mucor, Rhizopus
What are the causative fungi for Systemic infections?
Coccidioides. Histoplasma. Blastomyces. Paracoccidioides
What is Dermatophytoses?
Cutaneous infections caused by Fungi
What types of infections fall under Dermatophytoses?
Athlete’s foot (tinea pedis), jock itch (tinea cruris). Ringworm. Dermatophytid: antibody response to circulation fungal antigens - skin lesions
Which Fungi are often associated with Dermatophytoses?
Epidermophyton. Microsporum. Trichophyton
What are the general characteristics of Subcutaneous infections caused by Fungi?
Slow spreading from site of injury. Rarely becomes systemic, or serious. Granulomatous response (macrophages). Lymphatic involvement
What are the different Subcutaneous infections caused by Fungi?
Sporotrichosis. Chromomycosis (lesser importance). Mycetoma (lesser importance)
What is Sporotrichosis?
Type of SubQ Infection. Dimorphic Sporothrix. Spread from vegetation, e.g. thorn pricks
What is Chromomycosis?
Type of SubQ Infection. Caused from several soil fungi (Fonsecaea, Phialophora, Cladosporium). Spread when cuts are exposed to soil, e.g. gardening
What is Mycetoma?
Type of SubQ Infection. Caused from several soil fungi (Petriellidium, Madurella). Spread from soil
What are some general characteristics of Systemic Infections caused by Fungi?
Inhalation into lungs. Soil resident mycelial form. Airborne spores inhaled, differentiate into yeasts into the lungs. Assymptomatic, self-limiting (except in immunocompromised: HIV, drugs). Disseminated, serious. Non-contagious
What are the steps that Aspergillus go through when inhaled?
Inactive conidia are inhaled. Conidia lodge in lower respiratory tract. Conidia swell and shed outer coat. Conidia germinate into hyphae (blocked by macrophages). Hyphae invade lung and systemic vessels (blocked by neutrophils). If defenses fail, hyphae break off and disseminate to distal organs (blocked by neutrophils)
What is Coccidioidomycosis?
Systemic infection caused by Coccidioides immitis. Dimorphic: mold in soil, spherule in infected human tissues. Hyphae form arthrospores that can be inhaled. Endemic in Southern California, AZ, NM
What is Histoplasmosis?
Systemic infection caused by Histoplasma capsulatum. Dimorphic: mold in soil, yeast in infected human tissues. Tuberculate macroconidia; microconidia spores transmit infection when inhaled. Thrives in bird droppings. Infects and transmitted by bats; from disturbed bat guano. Develops in macrophages. Mild (most) infections asymptomatic
What is Blastomycosis?
Systemic infection caused by Blastomyces dermatitidis. Dimorphic: mold in soil, yeast in infected human tissues
What is Paracoccidioidomycosis?
Systemic infection caused by Paracoccidioides brasiliensis. Dimorphic: mold in soil, yeast in infected human tissues. Not typical in US
What is Candidiasis?
Opportunistic infection caused by Candida albicans (normal flora). Yeast; pseudohyphae (single yeast “glued” together). No transmission since it’s resident. Systemic infection only develops when immune system falters
What is Cryptococcosis (Cryptococcal Meningitis)?
Opportunistic infection caused by Cryptococcus neoformans. Yeast, soil containing bird droppings. Major problem in AIDs
What is India Ink Staining used for?
Cryptococcus neoformans d/t its wide polysaccharide capsule
What is Aspergillosis?
Opportunistic infection caused by Aspergillus fumigatus (and others). Molds, form “fungus balls” in lungs. Grow on decaying vegetation. Airborne; also wound entry
What is Pneumocystis pneumonia caused by?
Pneumocystis jirovecii
What is Mucormycosis?
Opportunistic infection caused by Mucor, Rhizopus, and others. Molds, airborne entry, grow in body in walls of blood vessels
What does the term Conidia mean?
Asexual reproductive structures
What does the term Dimorphic mean?
Can grow as either mold or yeast
What does the term Hyphae mean?
Long filaments
What does the term Mycoses mean?
Infections d/t fungus
