Mycology Flashcards
(16 cards)
- Types of fungi?
- Habitat?
Two types of fungi:
- Yeast - single cell
- Mold - long hyphae and form a mat
Fungi are:
- Eukaryotic (bacteria are prokaryotic)
- Obligate aerobe
Habit is environment, exception is Candida albicans (human host)
Fungi virulence factors
- What are the cell wall and membrane made of?
- Clinical significance?
Fungi virulence factors
- Capsule - antiphagocytic
- Cell wall made of chitin polysaccharide (not peptidoglycan so abx does not work)
- Cell membrane contains ergosterol - most antifungals work by disrupting ergosterol
What is the clinical significance of fungi being dimorphic?
Many fungi are dimorphic
- These fungi can grow TWO different way (e.g. Valley Fever)
- Form different structures at different temperatures
Pityriasis versicolor (Tinea versicolor)
Pityriasis versicolor (Tinea versicolor) = superficial infection, pigment change, spaghetti & meatballs, wrestlers, yogis, surfers
- Hypo or hyperpigmented
- About the volume you have been exposed to
- UV exposure causes skin around patches to tan
- Dx with KOH prep
Cutaneous fungal infections
- Known as?
- Affects?
- Most important ones?
- How to dx?
Cutaneous fungal infections
- Known as the dermatophytoses
- Skin, hair, nails
- Pruritic
- Broken hairs
- Damaged nails
- Inflamed circular border with central clearing
- Most important ones:
- Trichophyton
- Epidermophyton
- Microsporum (ring worm)
- Diagnosis
- KOH
- Branched hyphae (as opposed to spaghetti and meatballs)
Cutaneous fungal infections: dermatophytoses
What are all the names according to location on body?
Cutaneous fungal infections: dermatophytoses
- Tinea corporis - body
- Tinea cruris - jock itch
- Tinea pedis - athlete’s foot
- Tinea capitis - scalp (common in children)
- Tina unguium - onychomycosis
Candida albicans
Candida albicans = cutaneous infection, thrush, candida vaginitis, diaper rash (satellite lesions), immunocompromised patients, after abx
- Lives in humans, not the environment
- Oral thrush
- Creamy, white exudate
- Hard to scrape off with tongue depressor
- Tx is “swish and spit”
- Candida vaginitis
- Cottage cheese discharge
- Diaper rash
- Satellite lesions
- Immunocompromised patients
- Fungus in blood
Sprothrix schenckii (sporotrichosis)
Sprothrix schenckii (sporotrichosis) = subcutaneous infection, rose thorns, gardeners, dimophic
- Lives in soil and on plants
- Enters body after trauma
- Dimorphic - yeast at high temps and branching hyphae at lower temps
Systemic fungal infections
- 3 types
- How do you get infection?
Systemic fungal infections = NOT contagious person to person
- 3 types:
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Coccidioides immitis
- Inhalation of dimorphic fungi spores
- Breathe in spores from soil and they go from mold to yeast
Histoplasma capsulatum
Histoplasma capsulatum = histoplasmosis, bats and bridges
- Causes histoplasmosis
- Mississippi and Ohio rivers
- Grows in soil that is contaminated with bird and bat droppings
Blastomyces dermatitidis
Blastomyces dermatitidis = blastomycosis, rivers and lakes
- Causes blastomycosis
- Mississippi and Ohio rivers, and Great Lakes
- Grows in soil, wood, and leaves
Coccidioides immitis / coccidioidomycosis
Coccidioides immitis / coccidioidomycosis = Valley Fever, erythema nodosum (rash), granulomas on CXR, opportunistic infection
- AZ, CA, NM, Mexico
- Aka Desert Rheumatism
- Can present clinically as:
- Asymptomatic
- URI / flu
- Pneumonia
- Erythema nodosum (rash)
- Granuloma on CXR
Cryptococcosis
Cryptococcosis = pigeons, opportunistic infection, most common life threatening fungal dz in AIDS patients, meningitis
- Crytococcus neoformans
- Yeast, not dimorphic
- Found in soil with pigeon droppings
- Disease can manifest as:
- Lung infection
- Meningitis (cryptococcal meningitis)
Aspergillosis
Aspergillosis = decaying vegetation, opportunistic infection, asthma like symptoms
- Aspergillus fumigatus
- Mold with spores, not dimorphic
- Grows in nature on decaying vegetation
- Can cause infection of skin, eyes, ears, and lungs
- Allergic reaction in airway like asthma
- Allergic bronchopulmonary aspergillosis (ABPA)
- Cough up brown phelgm containing hyphae
Mucormycosis
Mucormycosis = cause blood vessel invasion, infarction of tissue distal to blockage (will eat away at brain), opportunistic infection
- Rhizopus species
- Mold in environment, not dimorphic
Pneumocystis jirovecii
Pneumocystis jirovecii = PCP, most common opportunistic infection in AIDS patients, tx with Bactrim, those on Prednisone at risk, prophylactic abx given
- Yeast
- In normal host: lives in lung without causing problems
- In immunocompromised host:
- Causes severe pneumonia
- PCP - pneumocytosis carinii pneumonia
