Introduction to Fungus and Mycoses Flashcards
Systemic mycoses can all cause?
- Pneumonia and can disseminate
- systemic mycoses can form granulomas (like TB)
All systemic mycosis are caused by what type of fungi? Exception?
- Dimorphic fungi:
- cold = mold
- heat =yeast
- exception is coccidioidomycosis which is a spherule (not yeast) in tissue
What are the 4 systemic/ endemic Mycoses?
- Histoplasmosis
- Blostomycosis
- Coccidioidomycosis
- Paracoccidioidomycosis
What are the different forms of fungi?
- Multicellular filamentous structures (molds)
- Unicellular forms (yeast)
- Dimorphic (either form depending on conditions such as temperature and environment)
Fungal cell membrane made up of ? Cell wall?
- Membrane= sterols
- Cell wall=chitin
How does fungi cause disease?
- Both direct invasion and host immune response
- (NO toxins released)
How do yeast cells reproduce?
-
budding
- buds are called blastoconidia
Definition of Hyphae? Mycelia?
- Hypahe: Continuous multinucleated non-septated/septated protoplasm
- Mycelia: cluster of hyphae
Sexual reproduction of fungus occurs via? Example?
-
Sporangia:
- sporangiophore with sporangium and sporangiospore;
- spores inside are what get inhaled;
- spores have to germinate and form new fungus
- sporangiophore with sporangium and sporangiospore;
- ex: Rhizopus species
Asexual reproduction of fungus occurs via? Example?
- Conidia: with conidiospore
- ex: Aspergillus species
- Histoplasmosis is found in?
- What part of country?
- Found in soil enriched with bird and bat poop
- Mississippi and Ohio river valleys
What cell can Histoplasmosis hide in?
Macrophages
- How is Histoplasmosis transmitted?
- What does it cause?
- Inhalation
- Acute and chronic pulmonary disseminated disease
- (AIDS)
- mucosal ulcer
All endemic/ systemic mycosis have what as primary source of infection?
Lung
Where is the geographic region that Blastomycosis is found?
- Mississippi river valley
- southeastern states
- north-central states
What is primary site of infection of Blastomycosis? What does it cause
- Inhalation (lungs)
-
Causes:
- Skin lesions
- pulmonary disease
- disseminated infection (can reach the blood); form granulomatous nodules
What is geographic region that Coccidiomycoseis is found?
Southwestern United States, California
- Coccidioidomycosis causes?
- When does the case rate increase?
- What are the spherules filled with?
- Pneumonia and meningitis (pulmonary disease, 40% flu like)
- Case rate increases after earthquakes
- spores in dust are thrown in the air and inhaled —> spherules in lung filled with endospores
Where is Paracoccidioidomycoseis found?
-
South America
- similar features to Coccidioidomycosis (dimorphic)
What endemic/systemic mycoses are most common in cellular immunity deficiency?
- Disseminated histoplasmosis and coccidiomycosis
What are 5 opportunistic fungus?
- Pneumocystosis
- Mucormycosis (Mucor and Rhizopus spp.)
- Aspergillosis
- Cryptococcosis
- Candidiasis
Candida albicans has what form?
Dimorphic forms pseudohyphae and oval budding yeasts
Candida albicans causes what type of infection? Especially in which patients?
- Systemic or superficial fungal infections
- vagina, mouth, tongue, diaper rash
- especially in immunocompromised patients have oral esophageal thrush
Cryptococcosis neoformans has what type of form? Virulence factor
- Heavily encapsulated yeast (capsule “crypt”)
- has halo appearance
-
virulence factor:
- antiphagocytic polysaccharide capsule
Where is Cryptococcosis neoformans found and how is it acquired?
- Found in soil, pigeon droppings
- Mississippi River Valley and eastern states
- acquired through inhalation
- dissemination to mininges (brain)
How does Cryptococcosis most commonly present as?
- Chronic meningitis
- Lung and brain infection
- acute pulmonary infections
What groups are at risk for Cryptococcosis infection?
- T cell abnormalities:
- HIV
- hematologic malignancy
- organ or bone marrow transplant
- corticosteroids or other immunosuppressive drugs
Aspergillosis have what kind of form?
- V shaped hyphae that branch at a 45 degree angle
- mold produces conidia in radiating chains at end of conidiosphore
How is Aspergillosis acquired?
- Acquired by inhalation;
- lung= primary site of infection
- (common environmental mold)
What does Aspergillosis cause?
- angioinvasion (lung and CNS)
- hemorrhage and tissue infarction,
- especially in the lungs
- Mucormycosis (Rhizopus, Mucor spp.) hyphae form?
- Where is it found?
- Common environmental mold
- Ribbon like hyphae with wide angle branching (90 degrees)
Mucormycosis cause disease mostly in what patients?
- angioinvasion in:
- immune suppressed patients
- or diabetes (especially diabetic ketoacidosis)
Pneumocystosis has what form and how does it enter host?
Yeast-like and it is inhaled
- Pneumocystosis infection is predisposed in what patients?
- What does it present as?
-
Immunocompromised,
- e.g. AIDs
-
Presents as:
- pneumonia with hypoxia (pneumocystis pneumonia)
Sporotrichiosis is caused by which fungus? What is form?
Sporothrix schenckii
- dimorphic fungus
- Where is sporotrichiosis found
- Route of infection?
- Clinical manifestation?
- Found in soil, moss, decaying vegetation (problem for gardeners)
- from thorn prick, rose garden
- cause cutaneous ulcer
Mycetoma is found mostly where? Clinical manifestation and treatment?
- Tropics
- Chronic granulomas with discharge (affects subcutaneous tissues)
- Tx: surgical extirpation
Dermatophyte infections is caused by what 3 genera?
- Trichophyton
- Microsporum
- Epidermophyton
What parts of body does a Dermatophyte infect?
- Stratum corneum
- hair shafts
- nails
Dermatophyte infections cause?
- Tinea corporis (body); ringworm
- Tinea pedis (feet); athletes foot
- Tinea capitis (head)
- Tinea cruris (crotch); jock itch
- Tinea unguium (nails)
What is a superficial mycoses?
-
Malassezia sp.
- Normal colonizers of stratum corneum
- M. furfur:
- Tinea versicolor
- M. globosa:
- seborrheic dermatitis
Organism feature of Blastomycosis?
Dimorphic BBB- broad based budding
What are two risk population for Candidiasis?
- Immune suppressed patients
- Chronic granulomatous disease
What is route of infection of Candidiasis?
Mucous membranes
Where is Candidiasis normally found?
- Normal flora of skin, mucous membrane, GIT
- opportunistic
What population is at risk for infection by Aspergillus?
Immune compromised
Route of infection of mucormycosis?
Inhalation
Chromoblastomycosis found where? Clinical manifestation/ people at risk?
- Found in tropics and subtropics
- Problem for people who spend more time outdoors
- Cause slow forming lesions resulting in epithelial hyperplasia, fibrosis
Where are dermatophytes normally found?
Direct contact with infected host or exfoliated skin
Who is more at risk of Malassezia sp. infection?
- young adults in hot weather
- cause:
- tinea versicolor (hypo/hyper pigmentation)
- seborrheic dermatitis
