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Fungi: saprobes
organisms that live on dead or decaying matter
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Fungi Eukaryotic
Cell wall?
cell membrane ?
Cell wall rigid & composed of chitin & glucan
Ergosterol is substituted for cholesterol
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Hyphae
Long, branching filamentous cells of fungus
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Conidia
Asexual, non-motile spores of fungus. Can form at the tips of the growing hyphae on a specialized structure called a conidiophire
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Yeasts are unicellular or multicellular?
unicellular
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Molds are unicellular or multicellular?
Multicellular
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Arthrospores (arthroconidia) are...
Asexual, formed from fragmentation of septated hyphae into single cells
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Chlamydospores (chlamydoconidia) are
Asexual, Thick-walled spore, formed by rounding and enlargement within hyphael segment
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Sporangiospores are
asexual, Endospores inside spherules (sporangia) in tissue
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Rhizopus growth? phylum?
Non septated hyphae, Zygomycota
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Aspergillus growth? Phylum?
Dimorphic Ascomycota
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Blastomyces growth? Phylum?
Yeastlike Ascomycota
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Histoplasma growth? phylum?
septated hyphae, Ascomycota
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Coccidioides immitis growth? phylum?
Septated hyphae, Ascomycota
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Candida albicans growth and phylum?
Septated hyphae, Ascomycota
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Pneumocystis growth & phylum?
Septated hyphae, Ascomycota
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Cryptococcus neoformans growth & phylum?
Septated hyphae, Basidiomycota
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Dimorphic pathogens are
Thermal (exist as yeasts or spherules at 37° C and molds at 25° C)
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Which mycoses causes superficial infection, pityriasis versicolor- discoloration or depigmentation and scaling of the skin
Malassezia furufr
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Dermatophytoses caused by
Tineas- ringworms
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Onychomycosis caused by
Trychophyton rubrum
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Subcutaneous mycoses infections (sporotrichosis) caused by
Sporothrix schenckii
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India ink used to diagnose which pathogen?
Cryptococcus neoformans
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Blastomyces dermatitidis dimorphic or no? Infection via...?
Dimorphic. Infection is by inhalation of aerosolized conidia (areas of moist soil, decomposing organic debris). Common infection among dogs
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Blastomyces dermatitidis causes? dissemination?
Blastomycosis (may resemble TB). Dissemination via infected macrophages to skin, bone, urinary tract, CNS in immunocompromised.
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Histoplasma capsulatum dimorphic? What stain is used? Known to be...
Dimorphic. Giemsa stain. Most common pulmonary and systemic mycosis of humans.
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Histoplasma capsulatum has 2 conidia forms
1.Large (8 to 15 μm), thick-walled, spherical macroconidia with spikelike projections (tuberculate macroconidia) that arise from short conidiophores
2.small, oval microconidia (2 to 4 μm) with smooth or slightly rough walls that are sessile or on short stalks
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Histoplasma capsulatum distribution? Pathogenesis?
in soils w/ high nitrogen content, Especially areas contaminated w/ bird or bat droppings. Multiples in phagolysosome & lyse host cell.
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Acute pulmonary histoplasmosis
Flulike illness w/ fever, chills, headache, cough, myalgias, chest pain. Mediastinal lymph node enlargement (can lead to mediastinal fibrosis) occurs in most pts. Usually resolves w/ supportive care, but can progress to acute respiratory distress syndrome
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Disseminated histoplasmosis
most likely to affect pts w/ underlying disorders of cell-mediated immunity. Mucocutatneous lesions & hepatosplenomegaly are common.
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Coccidioides dimorphic? Acquired via? Infectious form?
Dimorphic. Inhalation. Mold, infectious arthroconidia
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Coccidioides immitis location
California, found in soil late summer/early fall (dusty season)
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Coccidioides posadasii location
desert southwestern US, northern Mexico, and scattered areas of central and South America. Found in soil late summer/early fall (dusty season)
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Coccidioides primary disease
Valley Fever: asymptomatic, self-limited flulike illness marked, Allergic rxn, Erythema nodosum (red nodules)
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Coccidioides secondary disease
progressive pulmonary disease w/ nodules, cavitary disease. Lesions tend to calcify as they heal. Dissemination to skin, soft tissues, bones, joints, and meninges. More likely found in 3rd tri pregnancy & immunocompromised pts.
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Coccidioides Diagnosis via
Nucleic acid hybridization
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Paracoccidioides brasiliensis dimorphic? Transmission route? Yeast form in tissue looks like...
Dimorphic. Inhalation or traumatic inoculation. Pilot's wheel.
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Paracoccidioides brasiliensis common affects?
Latin America (Brazil), children, exposure to soil, depressed cell-mediated immunity
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Paracoccidioidomycosis. Dissemination?
South American blastomycosis. Dissemination frequently involves mucous membranes, skin, and lymph nodes
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Malassezia furfur (superficial) morphology? Transmission? Complications?
Lipophilic yeast. Person to person transmission of infected keratinous material. Normal to skin flora. Hair follicle- folliculitis; yeast thrives in sebaceous environment
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Malassezia furfur Diagnosis
KOH stain of skin scraping . Yeast clusters & short curved septate hyphae = “spaghetti and meatballs”. Coppery-orange fluorescence under UV, Calcofluor white, Culture (supplement with olive oil)
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Sporothrix schenckii (subcutaneous) infection dimorphic? Morphology?
Dimorphic. Conidiophores arise at right angles from the thin septate hyphae and are usually solitary. Cigar-shaped yeast.
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Sporothrix schenckii transmission
Trauma from thorns. Grows on bark of trees, shrubs, and garden plants. “rose-gardener” disease
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Pulmonary sporotrichosis (acquired via inhalation) associated with Alcoholics
Sporothrix schenckii
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Trichophyton infection is...? Two forms?
Cutaneous mycoses. microconidia are usually abundant. macroconidia absent or present in small numbers; when present, they are pencil-shaped and thin, with smooth walls
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Microsporum infection is...? morphology?
Cutaneous mycoses. multicelled macroconidia with thick, rough walls
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Epidermophytom infection is...? Morphology?
Cutaneous mycoses. microconidia absent; macroconidia typically club-shaped, with thin, smooth walls
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Trichomyton micro & macroconidia
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Microsporum micro & macroconidia
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Epidermophyton macroconidia
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Tinea corporis & its causative agent?
Dermatophyte infection of smooth or glabrous skin. May be caused by any dermatophyte
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Tinea cruris & causative agent?
Dermatophyte infection of groin. Trichophyton and Epidermophytom
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Tinea unguium & causative agent
Dermatophyte infection of nails. Trichophyton
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Tinea capitis usually caused by? Ectothrix? Endothrix?
Microsporum and Trichophyton. sheath of conidia formed on outside of hair shaft. Conidia formed w/in hair shaft
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Tineas favosa
most serious; associated w/ tinea capitis, causes permanent hair loss. Contagious
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Tinea barbae commonly caused by
Trichophyton
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Tinea pedis = Athlete's foot causative agent
Trichophyton and Epidermophytom
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Dermatophyte: Diagnosis
KOH preparation of skin or nail scrapings. Hyphae and arthroconidia in calcofluor white
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Cryptococcus neoformans morphology. Replication? Major virulence factor?
Encapsulated, yeast-like. Budding. Capsule that inhibits phagocytosis & Downregulates Th1 responses
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Cryptococcus neoformans transmission
In soil, pigeon droppings (inhalation). Opportunistic infection
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Cryptococcus neoformans Clinical Disease
Acute pulmonary disease, Cutaneous Cryptococcosis, Life-threatening encephalitis or meningoencephalitis
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Aspergillus fumigatus morphology
monomorphic. Branched, septate hyphae that produce conidial heads treelike pattern of branching. branches are dichotomous and usually arise at acute (∼45°) angles
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Aspergillus fumigatus transmission
Via inhalation. air, soil, and decaying matter.
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Aspergillus fumigatus : Clinical Disease
Allergic Bronchopulmonary symptoms & Allergic sinusitis. Colonization of lower airway- obstructive bronchial aspergillosis
–fungal ball, plugs composed of hyphal elements and mucinous material.
–Lung cavities
- –usually are asymptomatic; but can lead to pulmonary
- hemorrhage- need surgical removal
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Invasive pulmonary or disseminated aspergillosis
severely neutropenic and immunodeficient patients. necrosis and hemorrhage. Bronchial aspergillosis may cause wheezing, dyspnea, and hemoptysis. Cutaneous manifestations may occur
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Aspergillus fumigatus:Diagnosis
Chest CT scans demonstrate “halo” signs, Area infiltrate surrounding nodular densities
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Candida morphology
Oval yeastlike forms that produce buds or blastoconidia and chlamydospores. Produce pseudohyphae and true hyphae. Phenotypic switching may occur
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Candida hyphae & pseudohyphae
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Candida transmission
Normal commensals of diseased skin and mucosal membranes of GI, UG, and respiratory tracts. Also found in environment. Nosocomial transmission. Primary source of infection: the patient
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Candida Virulence
Surface molecules that permit adherence of the organism to other structures. Acid proteases and phospholipases. phenotypic switching
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Candida clinical manifestations
- Oropharyngeal candidiasis & Hematogenous candidiasis (candida septicemia). Vulvovaginal candidiasis. Skin infections (pruritic rash with erythematous vesiculopustular lesions). GI candidiasis, Pulmonary candidiasis, Urinary tract candidiasis, Meningitis, Endocarditis, myocarditis
- & pericarditis
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Candida diagnosis
KOH, PAS, and GMS stains
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Pneumocystis jiroveci development forms
- - trophozoite (trophic form), in which it often exists in clusters. Form inhaled; attach to alveoli
- –The uninucleate sporozoite (precystic form)
- - The cyst, which contains several intracystic bodies (spores)
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Pneumocystis jirovecii transmission
Acquisition early in life; commonly found in the lungs of healthy individuals. Person-to-person spread
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Pneumocystis jirovecii: Clinical Disease
Pneumocystosis. Interstitial pneumonitis & Extrapulmonary manifestations
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Pneumocystis jirovecii: Diagnosis
Giemsa & GMS stains. bronchoalveolar lavage (BAL) fluid in LM. Imaging.
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Coccidioides arthroconidia
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Blastomyces yeast budding
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